Implement structured logging using log/slog package

internal/api/middleware.go

@@ -5,11 +5,11 @@ package api // import "miniflux.app/v2/internal/api"
 
 import (
 	"context"
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/json"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/storage"
 )
 
@@ -40,25 +40,37 @@ func (m *middleware) apiKeyAuth(next http.Handler) http.Handler {
 		token := r.Header.Get("X-Auth-Token")
 
 		if token == "" {
-			logger.Debug("[API][TokenAuth] [ClientIP=%s] No API Key provided, go to the next middleware", clientIP)
+			slog.Debug("[API] Skipped API token authentication because no API Key has been provided",
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
 			next.ServeHTTP(w, r)
 			return
 		}
 
 		user, err := m.store.UserByAPIKey(token)
 		if err != nil {
-			logger.Error("[API][TokenAuth] %v", err)
 			json.ServerError(w, r, err)
 			return
 		}
 
 		if user == nil {
-			logger.Error("[API][TokenAuth] [ClientIP=%s] No user found with the given API key", clientIP)
+			slog.Warn("[API] No user found with the provided API key",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
 			json.Unauthorized(w, r)
 			return
 		}
 
-		logger.Info("[API][TokenAuth] [ClientIP=%s] User authenticated: %s", clientIP, user.Username)
+		slog.Info("[API] User authenticated successfully with the API Token Authentication",
+			slog.Bool("authentication_successful", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("username", user.Username),
+		)
+
 		m.store.SetLastLogin(user.ID)
 		m.store.SetAPIKeyUsedTimestamp(user.ID, token)
 
@@ -84,37 +96,60 @@ func (m *middleware) basicAuth(next http.Handler) http.Handler {
 		clientIP := request.ClientIP(r)
 		username, password, authOK := r.BasicAuth()
 		if !authOK {
-			logger.Debug("[API][BasicAuth] [ClientIP=%s] No authentication headers sent", clientIP)
+			slog.Warn("[API] No Basic HTTP Authentication header sent with the request",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
 			json.Unauthorized(w, r)
 			return
 		}
 
 		if username == "" || password == "" {
-			logger.Error("[API][BasicAuth] [ClientIP=%s] Empty username or password", clientIP)
+			slog.Warn("[API] Empty username or password provided during Basic HTTP Authentication",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
 			json.Unauthorized(w, r)
 			return
 		}
 
 		if err := m.store.CheckPassword(username, password); err != nil {
-			logger.Error("[API][BasicAuth] [ClientIP=%s] Invalid username or password: %s", clientIP, username)
+			slog.Warn("[API] Invalid username or password provided during Basic HTTP Authentication",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+				slog.String("username", username),
+			)
 			json.Unauthorized(w, r)
 			return
 		}
 
 		user, err := m.store.UserByUsername(username)
 		if err != nil {
-			logger.Error("[API][BasicAuth] %v", err)
 			json.ServerError(w, r, err)
 			return
 		}
 
 		if user == nil {
-			logger.Error("[API][BasicAuth] [ClientIP=%s] User not found: %s", clientIP, username)
+			slog.Warn("[API] User not found while using Basic HTTP Authentication",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+				slog.String("username", username),
+			)
 			json.Unauthorized(w, r)
 			return
 		}
 
-		logger.Info("[API][BasicAuth] [ClientIP=%s] User authenticated: %s", clientIP, username)
+		slog.Info("[API] User authenticated successfully with the Basic HTTP Authentication",
+			slog.Bool("authentication_successful", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("username", username),
+		)
+
 		m.store.SetLastLogin(user.ID)
 
 		ctx := r.Context()

internal/cli/ask_credentials.go

@@ -16,8 +16,7 @@ func askCredentials() (string, string) {
 	fd := int(os.Stdin.Fd())
 
 	if !term.IsTerminal(fd) {
-		fmt.Fprintf(os.Stderr, "This is not a terminal, exiting.\n")
-		os.Exit(1)
+		printErrorAndExit(fmt.Errorf("this is not a terminal, exiting"))
 	}
 
 	fmt.Print("Enter Username: ")

internal/cli/cleanup_tasks.go

@@ -4,10 +4,10 @@
 package cli // import "miniflux.app/v2/internal/cli"
 
 import (
+	"log/slog"
 	"time"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/metric"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/storage"
@@ -16,13 +16,18 @@ import (
 func runCleanupTasks(store *storage.Storage) {
 	nbSessions := store.CleanOldSessions(config.Opts.CleanupRemoveSessionsDays())
 	nbUserSessions := store.CleanOldUserSessions(config.Opts.CleanupRemoveSessionsDays())
-	logger.Info("[Sessions] Removed %d application sessions and %d user sessions", nbSessions, nbUserSessions)
+	slog.Info("Sessions cleanup completed",
+		slog.Int64("application_sessions_removed", nbSessions),
+		slog.Int64("user_sessions_removed", nbUserSessions),
+	)
 
 	startTime := time.Now()
 	if rowsAffected, err := store.ArchiveEntries(model.EntryStatusRead, config.Opts.CleanupArchiveReadDays(), config.Opts.CleanupArchiveBatchSize()); err != nil {
-		logger.Error("[ArchiveReadEntries] %v", err)
+		slog.Error("Unable to archive read entries", slog.Any("error", err))
 	} else {
-		logger.Info("[ArchiveReadEntries] %d entries changed", rowsAffected)
+		slog.Info("Archiving read entries completed",
+			slog.Int64("read_entries_archived", rowsAffected),
+		)
 
 		if config.Opts.HasMetricsCollector() {
 			metric.ArchiveEntriesDuration.WithLabelValues(model.EntryStatusRead).Observe(time.Since(startTime).Seconds())
@@ -31,9 +36,11 @@ func runCleanupTasks(store *storage.Storage) {
 
 	startTime = time.Now()
 	if rowsAffected, err := store.ArchiveEntries(model.EntryStatusUnread, config.Opts.CleanupArchiveUnreadDays(), config.Opts.CleanupArchiveBatchSize()); err != nil {
-		logger.Error("[ArchiveUnreadEntries] %v", err)
+		slog.Error("Unable to archive unread entries", slog.Any("error", err))
 	} else {
-		logger.Info("[ArchiveUnreadEntries] %d entries changed", rowsAffected)
+		slog.Info("Archiving unread entries completed",
+			slog.Int64("unread_entries_archived", rowsAffected),
+		)
 
 		if config.Opts.HasMetricsCollector() {
 			metric.ArchiveEntriesDuration.WithLabelValues(model.EntryStatusUnread).Observe(time.Since(startTime).Seconds())

internal/cli/cli.go

@@ -6,11 +6,13 @@ package cli // import "miniflux.app/v2/internal/cli"
 import (
 	"flag"
 	"fmt"
+	"io"
+	"log/slog"
+	"os"
 
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/database"
 	"miniflux.app/v2/internal/locale"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/ui/static"
 	"miniflux.app/v2/internal/version"
@@ -74,13 +76,13 @@ func Parse() {
 	if flagConfigFile != "" {
 		config.Opts, err = cfg.ParseFile(flagConfigFile)
 		if err != nil {
-			logger.Fatal("%v", err)
+			printErrorAndExit(err)
 		}
 	}
 
 	config.Opts, err = cfg.ParseEnvironmentVariables()
 	if err != nil {
-		logger.Fatal("%v", err)
+		printErrorAndExit(err)
 	}
 
 	if flagConfigDump {
@@ -88,12 +90,27 @@ func Parse() {
 		return
 	}
 
-	if config.Opts.LogDateTime() {
-		logger.EnableDateTime()
+	if flagDebugMode {
+		config.Opts.SetLogLevel("debug")
 	}
 
-	if flagDebugMode || config.Opts.HasDebugMode() {
-		logger.EnableDebug()
+	logFile := config.Opts.LogFile()
+	var logFileHandler io.Writer
+	switch logFile {
+	case "stdout":
+		logFileHandler = os.Stdout
+	case "stderr":
+		logFileHandler = os.Stderr
+	default:
+		logFileHandler, err = os.OpenFile(logFile, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0600)
+		if err != nil {
+			printErrorAndExit(fmt.Errorf("unable to open log file: %v", err))
+		}
+		defer logFileHandler.(*os.File).Close()
+	}
+
+	if err := InitializeDefaultLogger(config.Opts.LogLevel(), logFileHandler, config.Opts.LogFormat(), config.Opts.LogDateTime()); err != nil {
+		printErrorAndExit(err)
 	}
 
 	if flagHealthCheck != "" {
@@ -112,25 +129,23 @@ func Parse() {
 	}
 
 	if config.Opts.IsDefaultDatabaseURL() {
-		logger.Info("The default value for DATABASE_URL is used")
+		slog.Info("The default value for DATABASE_URL is used")
 	}
 
-	logger.Debug("Loading translations...")
 	if err := locale.LoadCatalogMessages(); err != nil {
-		logger.Fatal("Unable to load translations: %v", err)
+		printErrorAndExit(fmt.Errorf("unable to load translations: %v", err))
 	}
 
-	logger.Debug("Loading static assets...")
 	if err := static.CalculateBinaryFileChecksums(); err != nil {
-		logger.Fatal("Unable to calculate binary files checksum: %v", err)
+		printErrorAndExit(fmt.Errorf("unable to calculate binary file checksums: %v", err))
 	}
 
 	if err := static.GenerateStylesheetsBundles(); err != nil {
-		logger.Fatal("Unable to generate Stylesheet bundles: %v", err)
+		printErrorAndExit(fmt.Errorf("unable to generate stylesheets bundles: %v", err))
 	}
 
 	if err := static.GenerateJavascriptBundles(); err != nil {
-		logger.Fatal("Unable to generate Javascript bundles: %v", err)
+		printErrorAndExit(fmt.Errorf("unable to generate javascript bundles: %v", err))
 	}
 
 	db, err := database.NewConnectionPool(
@@ -140,19 +155,19 @@ func Parse() {
 		config.Opts.DatabaseConnectionLifetime(),
 	)
 	if err != nil {
-		logger.Fatal("Unable to initialize database connection pool: %v", err)
+		printErrorAndExit(fmt.Errorf("unable to connect to database: %v", err))
 	}
 	defer db.Close()
 
 	store := storage.NewStorage(db)
 
 	if err := store.Ping(); err != nil {
-		logger.Fatal("Unable to connect to the database: %v", err)
+		printErrorAndExit(err)
 	}
 
 	if flagMigrate {
 		if err := database.Migrate(db); err != nil {
-			logger.Fatal(`%v`, err)
+			printErrorAndExit(err)
 		}
 		return
 	}
@@ -180,12 +195,12 @@ func Parse() {
 	// Run migrations and start the daemon.
 	if config.Opts.RunMigrations() {
 		if err := database.Migrate(db); err != nil {
-			logger.Fatal(`%v`, err)
+			printErrorAndExit(err)
 		}
 	}
 
 	if err := database.IsSchemaUpToDate(db); err != nil {
-		logger.Fatal(`You must run the SQL migrations, %v`, err)
+		printErrorAndExit(err)
 	}
 
 	// Create admin user and start the daemon.
@@ -205,3 +220,8 @@ func Parse() {
 
 	startDaemon(store)
 }
+
+func printErrorAndExit(err error) {
+	fmt.Fprintf(os.Stderr, "%v\n", err)
+	os.Exit(1)
+}

internal/cli/create_admin.go

@@ -4,11 +4,9 @@
 package cli // import "miniflux.app/v2/internal/cli"
 
 import (
-	"fmt"
-	"os"
+	"log/slog"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/validator"
@@ -26,17 +24,17 @@ func createAdmin(store *storage.Storage) {
 	}
 
 	if store.UserExists(userCreationRequest.Username) {
-		logger.Info(`User %q already exists, skipping creation`, userCreationRequest.Username)
+		slog.Info("Skipping admin user creation because it already exists",
+			slog.String("username", userCreationRequest.Username),
+		)
 		return
 	}
 
 	if validationErr := validator.ValidateUserCreationWithPassword(store, userCreationRequest); validationErr != nil {
-		fmt.Fprintf(os.Stderr, "%s\n", validationErr)
-		os.Exit(1)
+		printErrorAndExit(validationErr.Error())
 	}
 
 	if _, err := store.CreateUser(userCreationRequest); err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err)
-		os.Exit(1)
+		printErrorAndExit(err)
 	}
 }

internal/cli/daemon.go

@@ -5,6 +5,7 @@ package cli // import "miniflux.app/v2/internal/cli"
 
 import (
 	"context"
+	"log/slog"
 	"net/http"
 	"os"
 	"os/signal"
@@ -13,7 +14,6 @@ import (
 
 	"miniflux.app/v2/internal/config"
 	httpd "miniflux.app/v2/internal/http/server"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/metric"
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/systemd"
@@ -21,7 +21,7 @@ import (
 )
 
 func startDaemon(store *storage.Storage) {
-	logger.Info("Starting daemon...")
+	slog.Debug("Starting daemon...")
 
 	stop := make(chan os.Signal, 1)
 	signal.Notify(stop, os.Interrupt)
@@ -44,26 +44,25 @@ func startDaemon(store *storage.Storage) {
 	}
 
 	if systemd.HasNotifySocket() {
-		logger.Info("Sending readiness notification to Systemd")
+		slog.Debug("Sending readiness notification to Systemd")
 
 		if err := systemd.SdNotify(systemd.SdNotifyReady); err != nil {
-			logger.Error("Unable to send readiness notification to systemd: %v", err)
+			slog.Error("Unable to send readiness notification to systemd", slog.Any("error", err))
 		}
 
 		if config.Opts.HasWatchdog() && systemd.HasSystemdWatchdog() {
-			logger.Info("Activating Systemd watchdog")
+			slog.Debug("Activating Systemd watchdog")
 
 			go func() {
 				interval, err := systemd.WatchdogInterval()
 				if err != nil {
-					logger.Error("Unable to parse watchdog interval from systemd: %v", err)
+					slog.Error("Unable to get watchdog interval from systemd", slog.Any("error", err))
 					return
 				}
 
 				for {
-					err := store.Ping()
-					if err != nil {
-						logger.Error(`Systemd Watchdog: %v`, err)
+					if err := store.Ping(); err != nil {
+						slog.Error("Unable to ping database", slog.Any("error", err))
 					} else {
 						systemd.SdNotify(systemd.SdNotifyWatchdog)
 					}
@@ -75,7 +74,7 @@ func startDaemon(store *storage.Storage) {
 	}
 
 	<-stop
-	logger.Info("Shutting down the process...")
+	slog.Debug("Shutting down the process")
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 
@@ -83,5 +82,5 @@ func startDaemon(store *storage.Storage) {
 		httpServer.Shutdown(ctx)
 	}
 
-	logger.Info("Process gracefully stopped")
+	slog.Debug("Process gracefully stopped")
 }

internal/cli/flush_sessions.go

@@ -5,7 +5,6 @@ package cli // import "miniflux.app/v2/internal/cli"
 
 import (
 	"fmt"
-	"os"
 
 	"miniflux.app/v2/internal/storage"
 )
@@ -13,7 +12,6 @@ import (
 func flushSessions(store *storage.Storage) {
 	fmt.Println("Flushing all sessions (disconnect users)")
 	if err := store.FlushAllSessions(); err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err)
-		os.Exit(1)
+		printErrorAndExit(err)
 	}
 }

internal/cli/health_check.go

@@ -4,11 +4,12 @@
 package cli // import "miniflux.app/v2/internal/cli"
 
 import (
+	"fmt"
+	"log/slog"
 	"net/http"
 	"time"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 )
 
 func doHealthCheck(healthCheckEndpoint string) {
@@ -16,18 +17,18 @@ func doHealthCheck(healthCheckEndpoint string) {
 		healthCheckEndpoint = "http://" + config.Opts.ListenAddr() + config.Opts.BasePath() + "/healthcheck"
 	}
 
-	logger.Debug(`Executing health check on %s`, healthCheckEndpoint)
+	slog.Debug("Executing health check request", slog.String("endpoint", healthCheckEndpoint))
 
 	client := &http.Client{Timeout: 3 * time.Second}
 	resp, err := client.Get(healthCheckEndpoint)
 	if err != nil {
-		logger.Fatal(`Health check failure: %v`, err)
+		printErrorAndExit(fmt.Errorf(`health check failure: %v`, err))
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != 200 {
-		logger.Fatal(`Health check failed with status code %d`, resp.StatusCode)
+		printErrorAndExit(fmt.Errorf(`health check failed with status code %d`, resp.StatusCode))
 	}
 
-	logger.Debug(`Health check is OK`)
+	slog.Debug(`Health check is passing`)
 }

internal/cli/logger.go

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package cli // import "miniflux.app/v2/internal/cli"
+
+import (
+	"io"
+	"log/slog"
+)
+
+func InitializeDefaultLogger(logLevel string, logFile io.Writer, logFormat string, logTime bool) error {
+	var programLogLevel = new(slog.LevelVar)
+	switch logLevel {
+	case "debug":
+		programLogLevel.Set(slog.LevelDebug)
+	case "info":
+		programLogLevel.Set(slog.LevelInfo)
+	case "warning":
+		programLogLevel.Set(slog.LevelWarn)
+	case "error":
+		programLogLevel.Set(slog.LevelError)
+	}
+
+	logHandlerOptions := &slog.HandlerOptions{Level: programLogLevel}
+	if !logTime {
+		logHandlerOptions.ReplaceAttr = func(groups []string, a slog.Attr) slog.Attr {
+			if a.Key == slog.TimeKey {
+				return slog.Attr{}
+			}
+
+			return a
+		}
+	}
+
+	var logger *slog.Logger
+	switch logFormat {
+	case "json":
+		logger = slog.New(slog.NewJSONHandler(logFile, logHandlerOptions))
+	default:
+		logger = slog.New(slog.NewTextHandler(logFile, logHandlerOptions))
+	}
+
+	slog.SetDefault(logger)
+
+	return nil
+}

internal/cli/refresh_feeds.go

@@ -4,11 +4,11 @@
 package cli // import "miniflux.app/v2/internal/cli"
 
 import (
+	"log/slog"
 	"sync"
 	"time"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	feedHandler "miniflux.app/v2/internal/reader/handler"
 	"miniflux.app/v2/internal/storage"
@@ -20,22 +20,39 @@ func refreshFeeds(store *storage.Storage) {
 	startTime := time.Now()
 	jobs, err := store.NewBatch(config.Opts.BatchSize())
 	if err != nil {
-		logger.Error("[Cronjob] %v", err)
+		slog.Error("Unable to fetch jobs from database", slog.Any("error", err))
 	}
 
 	nbJobs := len(jobs)
-	logger.Info("[Cronjob]] Created %d jobs from a batch size of %d", nbJobs, config.Opts.BatchSize())
+
+	slog.Info("Created a batch of feeds",
+		slog.Int("nb_jobs", nbJobs),
+		slog.Int("batch_size", config.Opts.BatchSize()),
+	)
+
 	var jobQueue = make(chan model.Job, nbJobs)
 
-	logger.Info("[Cronjob] Starting a pool of %d workers", config.Opts.WorkerPoolSize())
+	slog.Info("Starting a pool of workers",
+		slog.Int("nb_workers", config.Opts.WorkerPoolSize()),
+	)
+
 	for i := 0; i < config.Opts.WorkerPoolSize(); i++ {
 		wg.Add(1)
 		go func(workerID int) {
 			defer wg.Done()
 			for job := range jobQueue {
-				logger.Info("[Cronjob] Refreshing feed #%d for user #%d in worker #%d", job.FeedID, job.UserID, workerID)
+				slog.Info("Refreshing feed",
+					slog.Int64("feed_id", job.FeedID),
+					slog.Int64("user_id", job.UserID),
+					slog.Int("worker_id", workerID),
+				)
+
 				if err := feedHandler.RefreshFeed(store, job.UserID, job.FeedID, false); err != nil {
-					logger.Error("[Cronjob] Refreshing the feed #%d returned this error: %v", job.FeedID, err)
+					slog.Error("Unable to refresh feed",
+						slog.Int64("feed_id", job.FeedID),
+						slog.Int64("user_id", job.UserID),
+						slog.Any("error", err),
+					)
 				}
 			}
 		}(i)
@@ -47,5 +64,9 @@ func refreshFeeds(store *storage.Storage) {
 	close(jobQueue)
 
 	wg.Wait()
-	logger.Info("[Cronjob] Refreshed %d feed(s) in %s", nbJobs, time.Since(startTime))
+
+	slog.Info("Refreshed a batch of feeds",
+		slog.Int("nb_feeds", nbJobs),
+		slog.String("duration", time.Since(startTime).String()),
+	)
 }

internal/cli/reset_password.go

@@ -5,7 +5,6 @@ package cli // import "miniflux.app/v2/internal/cli"
 
 import (
 	"fmt"
-	"os"
 
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/storage"
@@ -16,27 +15,23 @@ func resetPassword(store *storage.Storage) {
 	username, password := askCredentials()
 	user, err := store.UserByUsername(username)
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err)
-		os.Exit(1)
+		printErrorAndExit(err)
 	}
 
 	if user == nil {
-		fmt.Fprintf(os.Stderr, "User not found!\n")
-		os.Exit(1)
+		printErrorAndExit(fmt.Errorf("user not found"))
 	}
 
 	userModificationRequest := &model.UserModificationRequest{
 		Password: &password,
 	}
 	if validationErr := validator.ValidateUserModification(store, user.ID, userModificationRequest); validationErr != nil {
-		fmt.Fprintf(os.Stderr, "%s\n", validationErr)
-		os.Exit(1)
+		printErrorAndExit(validationErr.Error())
 	}
 
 	user.Password = password
 	if err := store.UpdateUser(user); err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err)
-		os.Exit(1)
+		printErrorAndExit(err)
 	}
 
 	fmt.Println("Password changed!")

internal/cli/scheduler.go

@@ -4,16 +4,16 @@
 package cli // import "miniflux.app/v2/internal/cli"
 
 import (
+	"log/slog"
 	"time"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/worker"
 )
 
 func runScheduler(store *storage.Storage, pool *worker.Pool) {
-	logger.Info(`Starting background scheduler...`)
+	slog.Debug(`Starting background scheduler...`)
 
 	go feedScheduler(
 		store,
@@ -31,10 +31,12 @@ func runScheduler(store *storage.Storage, pool *worker.Pool) {
 func feedScheduler(store *storage.Storage, pool *worker.Pool, frequency, batchSize int) {
 	for range time.Tick(time.Duration(frequency) * time.Minute) {
 		jobs, err := store.NewBatch(batchSize)
-		logger.Info("[Scheduler:Feed] Pushing %d jobs to the queue", len(jobs))
 		if err != nil {
-			logger.Error("[Scheduler:Feed] %v", err)
+			slog.Error("Unable to fetch jobs from database", slog.Any("error", err))
 		} else {
+			slog.Info("Created a batch of feeds",
+				slog.Int("nb_jobs", len(jobs)),
+			)
 			pool.Push(jobs)
 		}
 	}

internal/config/config_test.go

@@ -8,6 +8,181 @@ import (
 	"testing"
 )
 
+func TestLogFileDefaultValue(t *testing.T) {
+	os.Clearenv()
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogFile() != defaultLogFile {
+		t.Fatalf(`Unexpected log file value, got %q`, opts.LogFile())
+	}
+}
+
+func TestLogFileWithCustomFilename(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_FILE", "foobar.log")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+	if opts.LogFile() != "foobar.log" {
+		t.Fatalf(`Unexpected log file value, got %q`, opts.LogFile())
+	}
+}
+
+func TestLogFileWithEmptyValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_FILE", "")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogFile() != defaultLogFile {
+		t.Fatalf(`Unexpected log file value, got %q`, opts.LogFile())
+	}
+}
+
+func TestLogLevelDefaultValue(t *testing.T) {
+	os.Clearenv()
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogLevel() != defaultLogLevel {
+		t.Fatalf(`Unexpected log level value, got %q`, opts.LogLevel())
+	}
+}
+
+func TestLogLevelWithCustomValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_LEVEL", "warning")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogLevel() != "warning" {
+		t.Fatalf(`Unexpected log level value, got %q`, opts.LogLevel())
+	}
+}
+
+func TestLogLevelWithInvalidValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_LEVEL", "invalid")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogLevel() != defaultLogLevel {
+		t.Fatalf(`Unexpected log level value, got %q`, opts.LogLevel())
+	}
+}
+
+func TestLogDateTimeDefaultValue(t *testing.T) {
+	os.Clearenv()
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogDateTime() != defaultLogDateTime {
+		t.Fatalf(`Unexpected log date time value, got %v`, opts.LogDateTime())
+	}
+}
+
+func TestLogDateTimeWithCustomValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_DATETIME", "false")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogDateTime() != false {
+		t.Fatalf(`Unexpected log date time value, got %v`, opts.LogDateTime())
+	}
+}
+
+func TestLogDateTimeWithInvalidValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_DATETIME", "invalid")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogDateTime() != defaultLogDateTime {
+		t.Fatalf(`Unexpected log date time value, got %v`, opts.LogDateTime())
+	}
+}
+
+func TestLogFormatDefaultValue(t *testing.T) {
+	os.Clearenv()
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogFormat() != defaultLogFormat {
+		t.Fatalf(`Unexpected log format value, got %q`, opts.LogFormat())
+	}
+}
+
+func TestLogFormatWithCustomValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_FORMAT", "json")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogFormat() != "json" {
+		t.Fatalf(`Unexpected log format value, got %q`, opts.LogFormat())
+	}
+}
+
+func TestLogFormatWithInvalidValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("LOG_FORMAT", "invalid")
+
+	parser := NewParser()
+	opts, err := parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	if opts.LogFormat() != defaultLogFormat {
+		t.Fatalf(`Unexpected log format value, got %q`, opts.LogFormat())
+	}
+}
+
 func TestDebugModeOn(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("DEBUG", "1")
@@ -18,8 +193,8 @@ func TestDebugModeOn(t *testing.T) {
 		t.Fatalf(`Parsing failure: %v`, err)
 	}
 
-	if !opts.HasDebugMode() {
-		t.Fatalf(`Unexpected debug mode value, got "%v"`, opts.HasDebugMode())
+	if opts.LogLevel() != "debug" {
+		t.Fatalf(`Unexpected debug mode value, got %q`, opts.LogLevel())
 	}
 }
 
@@ -32,8 +207,8 @@ func TestDebugModeOff(t *testing.T) {
 		t.Fatalf(`Parsing failure: %v`, err)
 	}
 
-	if opts.HasDebugMode() {
-		t.Fatalf(`Unexpected debug mode value, got "%v"`, opts.HasDebugMode())
+	if opts.LogLevel() != "info" {
+		t.Fatalf(`Unexpected debug mode value, got %q`, opts.LogLevel())
 	}
 }
 
@@ -1544,8 +1719,8 @@ Invalid text
 		t.Errorf(`Parsing failure: %v`, err)
 	}
 
-	if opts.HasDebugMode() != true {
-		t.Errorf(`Unexpected debug mode value, got "%v"`, opts.HasDebugMode())
+	if opts.LogLevel() != "debug" {
+		t.Errorf(`Unexpected debug mode value, got %q`, opts.LogLevel())
 	}
 
 	expected := ">#1234"

internal/config/options.go

@@ -15,7 +15,10 @@ import (
 
 const (
 	defaultHTTPS                              = false
+	defaultLogFile                            = "stderr"
 	defaultLogDateTime                        = false
+	defaultLogFormat                          = "text"
+	defaultLogLevel                           = "info"
 	defaultHSTS                               = true
 	defaultHTTPService                        = true
 	defaultSchedulerService                   = true
@@ -91,11 +94,13 @@ type Option struct {
 // Options contains configuration options.
 type Options struct {
 	HTTPS                              bool
+	logFile                            string
 	logDateTime                        bool
+	logFormat                          string
+	logLevel                           string
 	hsts                               bool
 	httpService                        bool
 	schedulerService                   bool
-	debug                              bool
 	serverTimingHeader                 bool
 	baseURL                            string
 	rootURL                            string
@@ -165,11 +170,13 @@ func NewOptions() *Options {
 
 	return &Options{
 		HTTPS:                              defaultHTTPS,
+		logFile:                            defaultLogFile,
 		logDateTime:                        defaultLogDateTime,
+		logFormat:                          defaultLogFormat,
+		logLevel:                           defaultLogLevel,
 		hsts:                               defaultHSTS,
 		httpService:                        defaultHTTPService,
 		schedulerService:                   defaultSchedulerService,
-		debug:                              defaultDebug,
 		serverTimingHeader:                 defaultTiming,
 		baseURL:                            defaultBaseURL,
 		rootURL:                            defaultRootURL,
@@ -231,11 +238,30 @@ func NewOptions() *Options {
 	}
 }
 
+func (o *Options) LogFile() string {
+	return o.logFile
+}
+
 // LogDateTime returns true if the date/time should be displayed in log messages.
 func (o *Options) LogDateTime() bool {
 	return o.logDateTime
 }
 
+// LogFormat returns the log format.
+func (o *Options) LogFormat() string {
+	return o.logFormat
+}
+
+// LogLevel returns the log level.
+func (o *Options) LogLevel() string {
+	return o.logLevel
+}
+
+// SetLogLevel sets the log level.
+func (o *Options) SetLogLevel(level string) {
+	o.logLevel = level
+}
+
 // HasMaintenanceMode returns true if maintenance mode is enabled.
 func (o *Options) HasMaintenanceMode() bool {
 	return o.maintenanceMode
@@ -246,11 +272,6 @@ func (o *Options) MaintenanceMessage() string {
 	return o.maintenanceMessage
 }
 
-// HasDebugMode returns true if debug mode is enabled.
-func (o *Options) HasDebugMode() bool {
-	return o.debug
-}
-
 // HasServerTimingHeader returns true if server-timing headers enabled.
 func (o *Options) HasServerTimingHeader() bool {
 	return o.serverTimingHeader
@@ -593,7 +614,6 @@ func (o *Options) SortedOptions(redactSecret bool) []*Option {
 		"DATABASE_MAX_CONNS":                     o.databaseMaxConns,
 		"DATABASE_MIN_CONNS":                     o.databaseMinConns,
 		"DATABASE_URL":                           redactSecretValue(o.databaseURL, redactSecret),
-		"DEBUG":                                  o.debug,
 		"DISABLE_HSTS":                           !o.hsts,
 		"DISABLE_HTTP_SERVICE":                   !o.httpService,
 		"DISABLE_SCHEDULER_SERVICE":              !o.schedulerService,
@@ -609,7 +629,10 @@ func (o *Options) SortedOptions(redactSecret bool) []*Option {
 		"INVIDIOUS_INSTANCE":                     o.invidiousInstance,
 		"KEY_FILE":                               o.certKeyFile,
 		"LISTEN_ADDR":                            o.listenAddr,
+		"LOG_FILE":                               o.logFile,
 		"LOG_DATE_TIME":                          o.logDateTime,
+		"LOG_FORMAT":                             o.logFormat,
+		"LOG_LEVEL":                              o.logLevel,
 		"MAINTENANCE_MESSAGE":                    o.maintenanceMessage,
 		"MAINTENANCE_MODE":                       o.maintenanceMode,
 		"METRICS_ALLOWED_NETWORKS":               strings.Join(o.metricsAllowedNetworks, ","),

internal/config/parser.go

@@ -10,7 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	url_parser "net/url"
+	"net/url"
 	"os"
 	"strconv"
 	"strings"
@@ -72,10 +72,25 @@ func (p *Parser) parseLines(lines []string) (err error) {
 		value := strings.TrimSpace(fields[1])
 
 		switch key {
+		case "LOG_FILE":
+			p.opts.logFile = parseString(value, defaultLogFile)
 		case "LOG_DATE_TIME":
 			p.opts.logDateTime = parseBool(value, defaultLogDateTime)
+		case "LOG_LEVEL":
+			parsedValue := parseString(value, defaultLogLevel)
+			if parsedValue == "debug" || parsedValue == "info" || parsedValue == "warning" || parsedValue == "error" {
+				p.opts.logLevel = parsedValue
+			}
+		case "LOG_FORMAT":
+			parsedValue := parseString(value, defaultLogFormat)
+			if parsedValue == "json" || parsedValue == "text" {
+				p.opts.logFormat = parsedValue
+			}
 		case "DEBUG":
-			p.opts.debug = parseBool(value, defaultDebug)
+			parsedValue := parseBool(value, defaultDebug)
+			if parsedValue {
+				p.opts.logLevel = "debug"
+			}
 		case "SERVER_TIMING_HEADER":
 			p.opts.serverTimingHeader = parseBool(value, defaultTiming)
 		case "BASE_URL":
@@ -247,19 +262,19 @@ func parseBaseURL(value string) (string, string, string, error) {
 		value = value[:len(value)-1]
 	}
 
-	url, err := url_parser.Parse(value)
+	parsedURL, err := url.Parse(value)
 	if err != nil {
 		return "", "", "", fmt.Errorf("config: invalid BASE_URL: %w", err)
 	}
 
-	scheme := strings.ToLower(url.Scheme)
+	scheme := strings.ToLower(parsedURL.Scheme)
 	if scheme != "https" && scheme != "http" {
 		return "", "", "", errors.New("config: invalid BASE_URL: scheme must be http or https")
 	}
 
-	basePath := url.Path
-	url.Path = ""
-	return value, url.String(), basePath, nil
+	basePath := parsedURL.Path
+	parsedURL.Path = ""
+	return value, parsedURL.String(), basePath, nil
 }
 
 func parseBool(value string, fallback bool) bool {

internal/database/database.go

@@ -6,6 +6,7 @@ package database // import "miniflux.app/v2/internal/database"
 import (
 	"database/sql"
 	"fmt"
+	"log/slog"
 	"time"
 
 	// Postgresql driver import
@@ -31,12 +32,13 @@ func Migrate(db *sql.DB) error {
 	var currentVersion int
 	db.QueryRow(`SELECT version FROM schema_version`).Scan(&currentVersion)
 
-	fmt.Println("-> Current schema version:", currentVersion)
-	fmt.Println("-> Latest schema version:", schemaVersion)
+	slog.Debug("Running database migrations",
+		slog.Int("current_version", currentVersion),
+		slog.Int("latest_version", schemaVersion),
+	)
 
 	for version := currentVersion; version < schemaVersion; version++ {
 		newVersion := version + 1
-		fmt.Println("* Migrating to version:", newVersion)
 
 		tx, err := db.Begin()
 		if err != nil {

internal/fever/handler.go

@@ -4,6 +4,7 @@
 package fever // import "miniflux.app/v2/internal/fever"
 
 import (
+	"log/slog"
 	"net/http"
 	"strconv"
 	"strings"
@@ -12,7 +13,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/json"
 	"miniflux.app/v2/internal/integration"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/proxy"
 	"miniflux.app/v2/internal/storage"
@@ -80,7 +80,9 @@ is_spark equal to 1.
 */
 func (h *handler) handleGroups(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
-	logger.Debug("[Fever] Fetching groups for user #%d", userID)
+	slog.Debug("[Fever] Fetching groups",
+		slog.Int64("user_id", userID),
+	)
 
 	categories, err := h.store.Categories(userID)
 	if err != nil {
@@ -130,7 +132,9 @@ For the “Sparks” super group the items should be limited to feeds with an is
 */
 func (h *handler) handleFeeds(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
-	logger.Debug("[Fever] Fetching feeds for userID=%d", userID)
+	slog.Debug("[Fever] Fetching feeds",
+		slog.Int64("user_id", userID),
+	)
 
 	feeds, err := h.store.Feeds(userID)
 	if err != nil {
@@ -183,7 +187,9 @@ A PHP/HTML example:
 */
 func (h *handler) handleFavicons(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
-	logger.Debug("[Fever] Fetching favicons for user #%d", userID)
+	slog.Debug("[Fever] Fetching favicons",
+		slog.Int64("user_id", userID),
+	)
 
 	icons, err := h.store.Icons(userID)
 	if err != nil {
@@ -247,16 +253,24 @@ func (h *handler) handleItems(w http.ResponseWriter, r *http.Request) {
 	case request.HasQueryParam(r, "since_id"):
 		sinceID := request.QueryInt64Param(r, "since_id", 0)
 		if sinceID > 0 {
-			logger.Debug("[Fever] Fetching items since #%d for user #%d", sinceID, userID)
+			slog.Debug("[Fever] Fetching items since a given date",
+				slog.Int64("user_id", userID),
+				slog.Int64("since_id", sinceID),
+			)
 			builder.AfterEntryID(sinceID)
 		}
 	case request.HasQueryParam(r, "max_id"):
 		maxID := request.QueryInt64Param(r, "max_id", 0)
 		if maxID == 0 {
-			logger.Debug("[Fever] Fetching most recent items for user #%d", userID)
+			slog.Debug("[Fever] Fetching most recent items",
+				slog.Int64("user_id", userID),
+			)
 			builder.WithSorting("id", "DESC")
 		} else if maxID > 0 {
-			logger.Debug("[Fever] Fetching items before #%d for user #%d", maxID, userID)
+			slog.Debug("[Fever] Fetching items before a given item ID",
+				slog.Int64("user_id", userID),
+				slog.Int64("max_id", maxID),
+			)
 			builder.BeforeEntryID(maxID)
 			builder.WithSorting("id", "DESC")
 		}
@@ -274,7 +288,9 @@ func (h *handler) handleItems(w http.ResponseWriter, r *http.Request) {
 			builder.WithEntryIDs(itemIDs)
 		}
 	default:
-		logger.Debug("[Fever] Fetching oldest items for user #%d", userID)
+		slog.Debug("[Fever] Fetching oldest items",
+			slog.Int64("user_id", userID),
+		)
 	}
 
 	entries, err := builder.GetEntries()
@@ -330,7 +346,9 @@ A request with the unread_item_ids argument will return one additional member:
 */
 func (h *handler) handleUnreadItems(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
-	logger.Debug("[Fever] Fetching unread items for user #%d", userID)
+	slog.Debug("[Fever] Fetching unread items",
+		slog.Int64("user_id", userID),
+	)
 
 	builder := h.store.NewEntryQueryBuilder(userID)
 	builder.WithStatus(model.EntryStatusUnread)
@@ -361,7 +379,9 @@ with the remote Fever installation.
 */
 func (h *handler) handleSavedItems(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
-	logger.Debug("[Fever] Fetching saved items for user #%d", userID)
+	slog.Debug("[Fever] Fetching saved items",
+		slog.Int64("user_id", userID),
+	)
 
 	builder := h.store.NewEntryQueryBuilder(userID)
 	builder.WithStarred(true)
@@ -389,7 +409,9 @@ id=? where ? is replaced with the id of the item to modify
 */
 func (h *handler) handleWriteItems(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
-	logger.Debug("[Fever] Receiving mark=item call for user #%d", userID)
+	slog.Debug("[Fever] Receiving mark=item call",
+		slog.Int64("user_id", userID),
+	)
 
 	entryID := request.FormInt64Value(r, "id")
 	if entryID <= 0 {
@@ -407,20 +429,32 @@ func (h *handler) handleWriteItems(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if entry == nil {
-		logger.Debug("[Fever] Marking entry #%d but not found, ignored", entryID)
+		slog.Debug("[Fever] Entry not found",
+			slog.Int64("user_id", userID),
+			slog.Int64("entry_id", entryID),
+		)
 		json.OK(w, r, newBaseResponse())
 		return
 	}
 
 	switch r.FormValue("as") {
 	case "read":
-		logger.Debug("[Fever] Mark entry #%d as read for user #%d", entryID, userID)
+		slog.Debug("[Fever] Mark entry as read",
+			slog.Int64("user_id", userID),
+			slog.Int64("entry_id", entryID),
+		)
 		h.store.SetEntriesStatus(userID, []int64{entryID}, model.EntryStatusRead)
 	case "unread":
-		logger.Debug("[Fever] Mark entry #%d as unread for user #%d", entryID, userID)
+		slog.Debug("[Fever] Mark entry as unread",
+			slog.Int64("user_id", userID),
+			slog.Int64("entry_id", entryID),
+		)
 		h.store.SetEntriesStatus(userID, []int64{entryID}, model.EntryStatusUnread)
 	case "saved":
-		logger.Debug("[Fever] Mark entry #%d as saved for user #%d", entryID, userID)
+		slog.Debug("[Fever] Mark entry as saved",
+			slog.Int64("user_id", userID),
+			slog.Int64("entry_id", entryID),
+		)
 		if err := h.store.ToggleBookmark(userID, entryID); err != nil {
 			json.ServerError(w, r, err)
 			return
@@ -436,7 +470,10 @@ func (h *handler) handleWriteItems(w http.ResponseWriter, r *http.Request) {
 			integration.SendEntry(entry, settings)
 		}()
 	case "unsaved":
-		logger.Debug("[Fever] Mark entry #%d as unsaved for user #%d", entryID, userID)
+		slog.Debug("[Fever] Mark entry as unsaved",
+			slog.Int64("user_id", userID),
+			slog.Int64("entry_id", entryID),
+		)
 		if err := h.store.ToggleBookmark(userID, entryID); err != nil {
 			json.ServerError(w, r, err)
 			return
@@ -457,7 +494,11 @@ func (h *handler) handleWriteFeeds(w http.ResponseWriter, r *http.Request) {
 	feedID := request.FormInt64Value(r, "id")
 	before := time.Unix(request.FormInt64Value(r, "before"), 0)
 
-	logger.Debug("[Fever] Mark feed #%d as read for user #%d before %v", feedID, userID, before)
+	slog.Debug("[Fever] Mark feed as read before a given date",
+		slog.Int64("user_id", userID),
+		slog.Int64("feed_id", feedID),
+		slog.Time("before_ts", before),
+	)
 
 	if feedID <= 0 {
 		return
@@ -465,7 +506,12 @@ func (h *handler) handleWriteFeeds(w http.ResponseWriter, r *http.Request) {
 
 	go func() {
 		if err := h.store.MarkFeedAsRead(userID, feedID, before); err != nil {
-			logger.Error("[Fever] MarkFeedAsRead failed: %v", err)
+			slog.Error("[Fever] Unable to mark feed as read",
+				slog.Int64("user_id", userID),
+				slog.Int64("feed_id", feedID),
+				slog.Time("before_ts", before),
+				slog.Any("error", err),
+			)
 		}
 	}()
 
@@ -483,7 +529,11 @@ func (h *handler) handleWriteGroups(w http.ResponseWriter, r *http.Request) {
 	groupID := request.FormInt64Value(r, "id")
 	before := time.Unix(request.FormInt64Value(r, "before"), 0)
 
-	logger.Debug("[Fever] Mark group #%d as read for user #%d before %v", groupID, userID, before)
+	slog.Debug("[Fever] Mark group as read before a given date",
+		slog.Int64("user_id", userID),
+		slog.Int64("group_id", groupID),
+		slog.Time("before_ts", before),
+	)
 
 	if groupID < 0 {
 		return
@@ -499,7 +549,12 @@ func (h *handler) handleWriteGroups(w http.ResponseWriter, r *http.Request) {
 		}
 
 		if err != nil {
-			logger.Error("[Fever] MarkCategoryAsRead failed: %v", err)
+			slog.Error("[Fever] Unable to mark group as read",
+				slog.Int64("user_id", userID),
+				slog.Int64("group_id", groupID),
+				slog.Time("before_ts", before),
+				slog.Any("error", err),
+			)
 		}
 	}()
 

internal/fever/middleware.go

@@ -5,11 +5,11 @@ package fever // import "miniflux.app/v2/internal/fever"
 
 import (
 	"context"
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/json"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/storage"
 )
 
@@ -26,25 +26,45 @@ func (m *middleware) serve(next http.Handler) http.Handler {
 		clientIP := request.ClientIP(r)
 		apiKey := r.FormValue("api_key")
 		if apiKey == "" {
-			logger.Info("[Fever] [ClientIP=%s] No API key provided", clientIP)
+			slog.Warn("[Fever] No API key provided",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
 			json.OK(w, r, newAuthFailureResponse())
 			return
 		}
 
 		user, err := m.store.UserByFeverToken(apiKey)
 		if err != nil {
-			logger.Error("[Fever] %v", err)
+			slog.Error("[Fever] Unable to fetch user by API key",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+				slog.Any("error", err),
+			)
 			json.OK(w, r, newAuthFailureResponse())
 			return
 		}
 
 		if user == nil {
-			logger.Info("[Fever] [ClientIP=%s] No user found with this API key", clientIP)
+			slog.Warn("[Fever] No user found with the API key provided",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
 			json.OK(w, r, newAuthFailureResponse())
 			return
 		}
 
-		logger.Info("[Fever] [ClientIP=%s] User #%d is authenticated with user agent %q", clientIP, user.ID, r.UserAgent())
+		slog.Info("[Fever] User authenticated successfully",
+			slog.Bool("authentication_successful", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.Int64("user_id", user.ID),
+			slog.String("username", user.Username),
+		)
+
 		m.store.SetLastLogin(user.ID)
 
 		ctx := r.Context()

internal/googlereader/handler.go

@@ -6,19 +6,18 @@ package googlereader // import "miniflux.app/v2/internal/googlereader"
 import (
 	"errors"
 	"fmt"
+	"log/slog"
 	"net/http"
-	"net/http/httputil"
 	"strconv"
 	"strings"
 	"time"
 
-	"github.com/gorilla/mux"
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/http/request"
+	"miniflux.app/v2/internal/http/response"
 	"miniflux.app/v2/internal/http/response/json"
 	"miniflux.app/v2/internal/http/route"
 	"miniflux.app/v2/internal/integration"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/proxy"
 	mff "miniflux.app/v2/internal/reader/handler"
@@ -26,6 +25,8 @@ import (
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/urllib"
 	"miniflux.app/v2/internal/validator"
+
+	"github.com/gorilla/mux"
 )
 
 type handler struct {
@@ -201,24 +202,25 @@ func (r RequestModifiers) String() string {
 // Serve handles Google Reader API calls.
 func Serve(router *mux.Router, store *storage.Storage) {
 	handler := &handler{store, router}
+	router.HandleFunc("/accounts/ClientLogin", handler.clientLoginHandler).Methods(http.MethodPost).Name("ClientLogin")
+
 	middleware := newMiddleware(store)
-	router.HandleFunc("/accounts/ClientLogin", middleware.clientLogin).Methods(http.MethodPost).Name("ClientLogin")
 	sr := router.PathPrefix("/reader/api/0").Subrouter()
 	sr.Use(middleware.handleCORS)
 	sr.Use(middleware.apiKeyAuth)
 	sr.Methods(http.MethodOptions)
-	sr.HandleFunc("/token", middleware.token).Methods(http.MethodGet).Name("Token")
-	sr.HandleFunc("/edit-tag", handler.editTag).Methods(http.MethodPost).Name("EditTag")
-	sr.HandleFunc("/rename-tag", handler.renameTag).Methods(http.MethodPost).Name("Rename Tag")
-	sr.HandleFunc("/disable-tag", handler.disableTag).Methods(http.MethodPost).Name("Disable Tag")
-	sr.HandleFunc("/tag/list", handler.tagList).Methods(http.MethodGet).Name("TagList")
-	sr.HandleFunc("/user-info", handler.userInfo).Methods(http.MethodGet).Name("UserInfo")
-	sr.HandleFunc("/subscription/list", handler.subscriptionList).Methods(http.MethodGet).Name("SubscriptonList")
-	sr.HandleFunc("/subscription/edit", handler.editSubscription).Methods(http.MethodPost).Name("SubscriptionEdit")
-	sr.HandleFunc("/subscription/quickadd", handler.quickAdd).Methods(http.MethodPost).Name("QuickAdd")
-	sr.HandleFunc("/stream/items/ids", handler.streamItemIDs).Methods(http.MethodGet).Name("StreamItemIDs")
-	sr.HandleFunc("/stream/items/contents", handler.streamItemContents).Methods(http.MethodPost).Name("StreamItemsContents")
-	sr.PathPrefix("/").HandlerFunc(handler.serve).Methods(http.MethodPost, http.MethodGet).Name("GoogleReaderApiEndpoint")
+	sr.HandleFunc("/token", handler.tokenHandler).Methods(http.MethodGet).Name("Token")
+	sr.HandleFunc("/edit-tag", handler.editTagHandler).Methods(http.MethodPost).Name("EditTag")
+	sr.HandleFunc("/rename-tag", handler.renameTagHandler).Methods(http.MethodPost).Name("Rename Tag")
+	sr.HandleFunc("/disable-tag", handler.disableTagHandler).Methods(http.MethodPost).Name("Disable Tag")
+	sr.HandleFunc("/tag/list", handler.tagListHandler).Methods(http.MethodGet).Name("TagList")
+	sr.HandleFunc("/user-info", handler.userInfoHandler).Methods(http.MethodGet).Name("UserInfo")
+	sr.HandleFunc("/subscription/list", handler.subscriptionListHandler).Methods(http.MethodGet).Name("SubscriptonList")
+	sr.HandleFunc("/subscription/edit", handler.editSubscriptionHandler).Methods(http.MethodPost).Name("SubscriptionEdit")
+	sr.HandleFunc("/subscription/quickadd", handler.quickAddHandler).Methods(http.MethodPost).Name("QuickAdd")
+	sr.HandleFunc("/stream/items/ids", handler.streamItemIDsHandler).Methods(http.MethodGet).Name("StreamItemIDs")
+	sr.HandleFunc("/stream/items/contents", handler.streamItemContentsHandler).Methods(http.MethodPost).Name("StreamItemsContents")
+	sr.PathPrefix("/").HandlerFunc(handler.serveHandler).Methods(http.MethodPost, http.MethodGet).Name("GoogleReaderApiEndpoint")
 }
 
 func getStreamFilterModifiers(r *http.Request) (RequestModifiers, error) {
@@ -276,8 +278,7 @@ func getStream(streamID string, userID int64) (Stream, error) {
 		case Like:
 			return Stream{LikeStream, ""}, nil
 		default:
-			err := fmt.Errorf("uknown stream with id: %s", id)
-			return Stream{NoStream, ""}, err
+			return Stream{NoStream, ""}, fmt.Errorf("googlereader: unknown stream with id: %s", id)
 		}
 	} else if strings.HasPrefix(streamID, fmt.Sprintf(UserLabelPrefix, userID)) || strings.HasPrefix(streamID, LabelPrefix) {
 		id := strings.TrimPrefix(streamID, fmt.Sprintf(UserLabelPrefix, userID))
@@ -286,8 +287,8 @@ func getStream(streamID string, userID int64) (Stream, error) {
 	} else if streamID == "" {
 		return Stream{NoStream, ""}, nil
 	}
-	err := fmt.Errorf("uknown stream type: %s", streamID)
-	return Stream{NoStream, ""}, err
+
+	return Stream{NoStream, ""}, fmt.Errorf("googlereader: unknown stream type: %s", streamID)
 }
 
 func getStreams(streamIDs []string, userID int64) ([]Stream, error) {
@@ -308,43 +309,43 @@ func checkAndSimplifyTags(addTags []Stream, removeTags []Stream) (map[StreamType
 		switch s.Type {
 		case ReadStream:
 			if _, ok := tags[KeptUnreadStream]; ok {
-				return nil, fmt.Errorf(KeptUnread + " and " + Read + " should not be supplied simultaneously")
+				return nil, fmt.Errorf("googlereader: %s ad %s should not be supplied simultaneously", KeptUnread, Read)
 			}
 			tags[ReadStream] = true
 		case KeptUnreadStream:
 			if _, ok := tags[ReadStream]; ok {
-				return nil, fmt.Errorf(KeptUnread + " and " + Read + " should not be supplied simultaneously")
+				return nil, fmt.Errorf("googlereader: %s ad %s should not be supplied simultaneously", KeptUnread, Read)
 			}
 			tags[ReadStream] = false
 		case StarredStream:
 			tags[StarredStream] = true
 		case BroadcastStream, LikeStream:
-			logger.Info("Broadcast & Like tags are not implemented!")
+			slog.Debug("Broadcast & Like tags are not implemented!")
 		default:
-			return nil, fmt.Errorf("unsupported tag type: %s", s.Type)
+			return nil, fmt.Errorf("googlereader: unsupported tag type: %s", s.Type)
 		}
 	}
 	for _, s := range removeTags {
 		switch s.Type {
 		case ReadStream:
 			if _, ok := tags[ReadStream]; ok {
-				return nil, fmt.Errorf(KeptUnread + " and " + Read + " should not be supplied simultaneously")
+				return nil, fmt.Errorf("googlereader: %s ad %s should not be supplied simultaneously", KeptUnread, Read)
 			}
 			tags[ReadStream] = false
 		case KeptUnreadStream:
 			if _, ok := tags[ReadStream]; ok {
-				return nil, fmt.Errorf(KeptUnread + " and " + Read + " should not be supplied simultaneously")
+				return nil, fmt.Errorf("googlereader: %s ad %s should not be supplied simultaneously", KeptUnread, Read)
 			}
 			tags[ReadStream] = true
 		case StarredStream:
 			if _, ok := tags[StarredStream]; ok {
-				return nil, fmt.Errorf(Starred + " should not be supplied for add and remove simultaneously")
+				return nil, fmt.Errorf("googlereader: %s should not be supplied for add and remove simultaneously", Starred)
 			}
 			tags[StarredStream] = false
 		case BroadcastStream, LikeStream:
-			logger.Info("Broadcast & Like tags are not implemented!")
+			slog.Debug("Broadcast & Like tags are not implemented!")
 		default:
-			return nil, fmt.Errorf("unsupported tag type: %s", s.Type)
+			return nil, fmt.Errorf("googlereader: unsupported tag type: %s", s.Type)
 		}
 	}
 
@@ -354,7 +355,7 @@ func checkAndSimplifyTags(addTags []Stream, removeTags []Stream) (map[StreamType
 func getItemIDs(r *http.Request) ([]int64, error) {
 	items := r.Form[ParamItemIDs]
 	if len(items) == 0 {
-		return nil, fmt.Errorf("no items requested")
+		return nil, fmt.Errorf("googlereader: no items requested")
 	}
 
 	itemIDs := make([]int64, len(items))
@@ -365,7 +366,7 @@ func getItemIDs(r *http.Request) ([]int64, error) {
 		if err != nil {
 			itemID, err = strconv.ParseInt(item, 16, 64)
 			if err != nil {
-				return nil, fmt.Errorf("could not parse item: %v", item)
+				return nil, fmt.Errorf("googlereader: could not parse item: %v", item)
 			}
 		}
 		itemIDs[i] = itemID
@@ -385,66 +386,191 @@ func checkOutputFormat(w http.ResponseWriter, r *http.Request) error {
 		output = request.QueryStringParam(r, "output", "")
 	}
 	if output != "json" {
-		err := fmt.Errorf("output only as json supported")
+		err := fmt.Errorf("googlereader: only json output is supported")
 		return err
 	}
 	return nil
 }
 
-func (h *handler) editTag(w http.ResponseWriter, r *http.Request) {
-	userID := request.UserID(r)
+func (h *handler) clientLoginHandler(w http.ResponseWriter, r *http.Request) {
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/edit-tag][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /accounts/ClientLogin",
+		slog.String("handler", "clientLoginHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
+
+	if err := r.ParseForm(); err != nil {
+		slog.Warn("[GoogleReader] Could not parse request form data",
+			slog.Bool("authentication_failed", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.Any("error", err),
+		)
+		json.Unauthorized(w, r)
+		return
+	}
 
-	err := r.ParseForm()
+	username := r.Form.Get("Email")
+	password := r.Form.Get("Passwd")
+	output := r.Form.Get("output")
+
+	if username == "" || password == "" {
+		slog.Warn("[GoogleReader] Empty username or password",
+			slog.Bool("authentication_failed", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+		)
+		json.Unauthorized(w, r)
+		return
+	}
+
+	if err := h.store.GoogleReaderUserCheckPassword(username, password); err != nil {
+		slog.Warn("[GoogleReader] Invalid username or password",
+			slog.Bool("authentication_failed", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("username", username),
+			slog.Any("error", err),
+		)
+		json.Unauthorized(w, r)
+		return
+	}
+
+	slog.Info("[GoogleReader] User authenticated successfully",
+		slog.Bool("authentication_successful", true),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.String("username", username),
+	)
+
+	integration, err := h.store.GoogleReaderUserGetIntegration(username)
 	if err != nil {
-		logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
+		json.ServerError(w, r, err)
+		return
+	}
+
+	h.store.SetLastLogin(integration.UserID)
+
+	token := getAuthToken(integration.GoogleReaderUsername, integration.GoogleReaderPassword)
+	slog.Debug("[GoogleReader] Created token",
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.String("username", username),
+	)
+
+	result := login{SID: token, LSID: token, Auth: token}
+	if output == "json" {
+		json.OK(w, r, result)
+		return
+	}
+
+	builder := response.New(w, r)
+	builder.WithHeader("Content-Type", "text/plain; charset=UTF-8")
+	builder.WithBody(result.String())
+	builder.Write()
+}
+
+func (h *handler) tokenHandler(w http.ResponseWriter, r *http.Request) {
+	clientIP := request.ClientIP(r)
+
+	slog.Debug("[GoogleReader] Handle /token",
+		slog.String("handler", "tokenHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
+
+	if !request.IsAuthenticated(r) {
+		slog.Warn("[GoogleReader] User is not authenticated",
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+		)
+		json.Unauthorized(w, r)
+		return
+	}
+
+	token := request.GoolgeReaderToken(r)
+	if token == "" {
+		slog.Warn("[GoogleReader] User does not have token",
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.Int64("user_id", request.UserID(r)),
+		)
+		json.Unauthorized(w, r)
+		return
+	}
+
+	slog.Debug("[GoogleReader] Token handler",
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", request.UserID(r)),
+		slog.String("token", token),
+	)
+
+	w.Header().Add("Content-Type", "text/plain; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte(token))
+}
+
+func (h *handler) editTagHandler(w http.ResponseWriter, r *http.Request) {
+	userID := request.UserID(r)
+	clientIP := request.ClientIP(r)
+
+	slog.Debug("[GoogleReader] Handle /edit-tag",
+		slog.String("handler", "editTagHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+	)
+
+	if err := r.ParseForm(); err != nil {
 		json.ServerError(w, r, err)
 		return
 	}
 
 	addTags, err := getStreams(r.PostForm[ParamTagsAdd], userID)
 	if err != nil {
-		logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 	removeTags, err := getStreams(r.PostForm[ParamTagsRemove], userID)
 	if err != nil {
-		logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 	if len(addTags) == 0 && len(removeTags) == 0 {
-		err = fmt.Errorf("add or/and remove tags should be supplied")
-		logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] ", clientIP, err)
+		err = fmt.Errorf("googlreader: add or/and remove tags should be supplied")
 		json.ServerError(w, r, err)
 		return
 	}
 	tags, err := checkAndSimplifyTags(addTags, removeTags)
 	if err != nil {
-		logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 
 	itemIDs, err := getItemIDs(r)
 	if err != nil {
-		logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 
-	logger.Debug("[GoogleReader][/edit-tag] [ClientIP=%s] itemIDs: %v", clientIP, itemIDs)
-	logger.Debug("[GoogleReader][/edit-tag] [ClientIP=%s] tags: %v", clientIP, tags)
+	slog.Debug("[GoogleReader] Edited tags",
+		slog.String("handler", "editTagHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+		slog.Any("item_ids", itemIDs),
+		slog.Any("tags", tags),
+	)
+
 	builder := h.store.NewEntryQueryBuilder(userID)
 	builder.WithEntryIDs(itemIDs)
 	builder.WithoutStatus(model.EntryStatusRemoved)
 
 	entries, err := builder.GetEntries()
 	if err != nil {
-		logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -477,7 +603,6 @@ func (h *handler) editTag(w http.ResponseWriter, r *http.Request) {
 	if len(readEntryIDs) > 0 {
 		err = h.store.SetEntriesStatus(userID, readEntryIDs, model.EntryStatusRead)
 		if err != nil {
-			logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 			json.ServerError(w, r, err)
 			return
 		}
@@ -486,7 +611,6 @@ func (h *handler) editTag(w http.ResponseWriter, r *http.Request) {
 	if len(unreadEntryIDs) > 0 {
 		err = h.store.SetEntriesStatus(userID, unreadEntryIDs, model.EntryStatusUnread)
 		if err != nil {
-			logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 			json.ServerError(w, r, err)
 			return
 		}
@@ -495,7 +619,6 @@ func (h *handler) editTag(w http.ResponseWriter, r *http.Request) {
 	if len(unstarredEntryIDs) > 0 {
 		err = h.store.SetEntriesBookmarkedState(userID, unstarredEntryIDs, false)
 		if err != nil {
-			logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 			json.ServerError(w, r, err)
 			return
 		}
@@ -504,7 +627,6 @@ func (h *handler) editTag(w http.ResponseWriter, r *http.Request) {
 	if len(starredEntryIDs) > 0 {
 		err = h.store.SetEntriesBookmarkedState(userID, starredEntryIDs, true)
 		if err != nil {
-			logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 			json.ServerError(w, r, err)
 			return
 		}
@@ -513,7 +635,6 @@ func (h *handler) editTag(w http.ResponseWriter, r *http.Request) {
 	if len(entries) > 0 {
 		settings, err := h.store.Integration(userID)
 		if err != nil {
-			logger.Error("[GoogleReader][/edit-tag] [ClientIP=%s] %v", clientIP, err)
 			json.ServerError(w, r, err)
 			return
 		}
@@ -529,22 +650,26 @@ func (h *handler) editTag(w http.ResponseWriter, r *http.Request) {
 	OK(w, r)
 }
 
-func (h *handler) quickAdd(w http.ResponseWriter, r *http.Request) {
+func (h *handler) quickAddHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/subscription/quickadd][ClientIP=%s] Incoming Request for userID  #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /subscription/quickadd",
+		slog.String("handler", "quickAddHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+	)
 
 	err := r.ParseForm()
 	if err != nil {
-		logger.Error("[GoogleReader][/subscription/quickadd] [ClientIP=%s] %v", clientIP, err)
 		json.BadRequest(w, r, err)
 		return
 	}
 
 	url := r.Form.Get(ParamQuickAdd)
 	if !validator.IsValidURL(url) {
-		json.BadRequest(w, r, fmt.Errorf("invalid URL: %s", url))
+		json.BadRequest(w, r, fmt.Errorf("googlereader: invalid URL: %s", url))
 		return
 	}
 
@@ -568,6 +693,15 @@ func (h *handler) quickAdd(w http.ResponseWriter, r *http.Request) {
 		json.ServerError(w, r, err)
 		return
 	}
+
+	slog.Debug("[GoogleReader] Added a new feed",
+		slog.String("handler", "quickAddHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+		slog.String("feed_url", newFeed.FeedURL),
+	)
+
 	json.OK(w, r, quickAddResponse{
 		NumResults: 1,
 		Query:      newFeed.FeedURL,
@@ -675,34 +809,37 @@ func move(stream Stream, destination Stream, store *storage.Storage, userID int6
 	return store.UpdateFeed(feed)
 }
 
-func (h *handler) editSubscription(w http.ResponseWriter, r *http.Request) {
+func (h *handler) editSubscriptionHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/subscription/edit][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /subscription/edit",
+		slog.String("handler", "editSubscriptionHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+	)
 
-	err := r.ParseForm()
-	if err != nil {
-		logger.Error("[GoogleReader][/subscription/edit] [ClientIP=%s] %v", clientIP, err)
+	if err := r.ParseForm(); err != nil {
 		json.BadRequest(w, r, err)
 		return
 	}
 
 	streamIds, err := getStreams(r.Form[ParamStreamID], userID)
 	if err != nil || len(streamIds) == 0 {
-		json.BadRequest(w, r, errors.New("no valid stream IDs provided"))
+		json.BadRequest(w, r, errors.New("googlereader: no valid stream IDs provided"))
 		return
 	}
 
 	newLabel, err := getStream(r.Form.Get(ParamTagsAdd), userID)
 	if err != nil {
-		json.BadRequest(w, r, fmt.Errorf("invalid data in %s", ParamTagsAdd))
+		json.BadRequest(w, r, fmt.Errorf("googlereader: invalid data in %s", ParamTagsAdd))
 		return
 	}
 
 	title := r.Form.Get(ParamTitle)
-
 	action := r.Form.Get(ParamSubscribeAction)
+
 	switch action {
 	case "subscribe":
 		_, err := subscribe(streamIds[0], newLabel, title, h.store, userID)
@@ -735,41 +872,42 @@ func (h *handler) editSubscription(w http.ResponseWriter, r *http.Request) {
 			}
 		}
 	default:
-		json.ServerError(w, r, fmt.Errorf("unrecognized action %s", action))
+		json.ServerError(w, r, fmt.Errorf("googlereader: unrecognized action %s", action))
 		return
 	}
 
 	OK(w, r)
 }
 
-func (h *handler) streamItemContents(w http.ResponseWriter, r *http.Request) {
+func (h *handler) streamItemContentsHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/stream/items/contents][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /stream/items/contents",
+		slog.String("handler", "streamItemContentsHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+	)
 
 	if err := checkOutputFormat(w, r); err != nil {
-		logger.Error("[GoogleReader][/stream/items/contents] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 
 	err := r.ParseForm()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/contents] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 	var user *model.User
 	if user, err = h.store.UserByID(userID); err != nil {
-		logger.Error("[GoogleReader][/stream/items/contents] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 
 	requestModifiers, err := getStreamFilterModifiers(r)
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/contents] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -780,11 +918,17 @@ func (h *handler) streamItemContents(w http.ResponseWriter, r *http.Request) {
 
 	itemIDs, err := getItemIDs(r)
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/contents] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
-	logger.Debug("[GoogleReader][/stream/items/contents] [ClientIP=%s] itemIDs: %v", clientIP, itemIDs)
+
+	slog.Debug("[GoogleReader] Fetching item contents",
+		slog.String("handler", "streamItemContentsHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+		slog.Any("item_ids", itemIDs),
+	)
 
 	builder := h.store.NewEntryQueryBuilder(userID)
 	builder.WithoutStatus(model.EntryStatusRemoved)
@@ -796,12 +940,12 @@ func (h *handler) streamItemContents(w http.ResponseWriter, r *http.Request) {
 		json.ServerError(w, r, err)
 		return
 	}
+
 	if len(entries) == 0 {
-		err = fmt.Errorf("no items returned from the database")
-		logger.Error("[GoogleReader][/stream/items/contents] [ClientIP=%s] %v", clientIP, err)
-		json.ServerError(w, r, err)
+		json.ServerError(w, r, fmt.Errorf("googlereader: no items returned from the database"))
 		return
 	}
+
 	result := streamContentItems{
 		Direction: "ltr",
 		ID:        fmt.Sprintf("feed/%d", entries[0].FeedID),
@@ -893,29 +1037,33 @@ func (h *handler) streamItemContents(w http.ResponseWriter, r *http.Request) {
 	json.OK(w, r, result)
 }
 
-func (h *handler) disableTag(w http.ResponseWriter, r *http.Request) {
+func (h *handler) disableTagHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/disable-tag][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /disable-tags",
+		slog.String("handler", "disableTagHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+	)
 
 	err := r.ParseForm()
 	if err != nil {
-		logger.Error("[GoogleReader][/disable-tag] [ClientIP=%s] %v", clientIP, err)
 		json.BadRequest(w, r, err)
 		return
 	}
 
 	streams, err := getStreams(r.Form[ParamStreamID], userID)
 	if err != nil {
-		json.BadRequest(w, r, fmt.Errorf("invalid data in %s", ParamStreamID))
+		json.BadRequest(w, r, fmt.Errorf("googlereader: invalid data in %s", ParamStreamID))
 		return
 	}
 
 	titles := make([]string, len(streams))
 	for i, stream := range streams {
 		if stream.Type != LabelStream {
-			json.BadRequest(w, r, errors.New("only labels are supported"))
+			json.BadRequest(w, r, errors.New("googlereader: only labels are supported"))
 			return
 		}
 		titles[i] = stream.ID
@@ -930,38 +1078,41 @@ func (h *handler) disableTag(w http.ResponseWriter, r *http.Request) {
 	OK(w, r)
 }
 
-func (h *handler) renameTag(w http.ResponseWriter, r *http.Request) {
+func (h *handler) renameTagHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/rename-tag][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /rename-tag",
+		slog.String("handler", "renameTagHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
 
 	err := r.ParseForm()
 	if err != nil {
-		logger.Error("[GoogleReader][/rename-tag] [ClientIP=%s] %v", clientIP, err)
 		json.BadRequest(w, r, err)
 		return
 	}
 
 	source, err := getStream(r.Form.Get(ParamStreamID), userID)
 	if err != nil {
-		json.BadRequest(w, r, fmt.Errorf("invalid data in %s", ParamStreamID))
+		json.BadRequest(w, r, fmt.Errorf("googlereader: invalid data in %s", ParamStreamID))
 		return
 	}
 
 	destination, err := getStream(r.Form.Get(ParamDestination), userID)
 	if err != nil {
-		json.BadRequest(w, r, fmt.Errorf("invalid data in %s", ParamDestination))
+		json.BadRequest(w, r, fmt.Errorf("googlereader: invalid data in %s", ParamDestination))
 		return
 	}
 
 	if source.Type != LabelStream || destination.Type != LabelStream {
-		json.BadRequest(w, r, errors.New("only labels supported"))
+		json.BadRequest(w, r, errors.New("googlereader: only labels supported"))
 		return
 	}
 
 	if destination.ID == "" {
-		json.BadRequest(w, r, errors.New("empty destination name"))
+		json.BadRequest(w, r, errors.New("googlereader: empty destination name"))
 		return
 	}
 
@@ -991,14 +1142,17 @@ func (h *handler) renameTag(w http.ResponseWriter, r *http.Request) {
 	OK(w, r)
 }
 
-func (h *handler) tagList(w http.ResponseWriter, r *http.Request) {
+func (h *handler) tagListHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][tags/list][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /tags/list",
+		slog.String("handler", "tagListHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
 
 	if err := checkOutputFormat(w, r); err != nil {
-		logger.Error("[GoogleReader][OutputFormat] %v", err)
 		json.BadRequest(w, r, err)
 		return
 	}
@@ -1023,14 +1177,17 @@ func (h *handler) tagList(w http.ResponseWriter, r *http.Request) {
 	json.OK(w, r, result)
 }
 
-func (h *handler) subscriptionList(w http.ResponseWriter, r *http.Request) {
+func (h *handler) subscriptionListHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/subscription/list][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /subscription/list",
+		slog.String("handler", "subscriptionListHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
 
 	if err := checkOutputFormat(w, r); err != nil {
-		logger.Error("[GoogleReader][/subscription/list] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1055,27 +1212,34 @@ func (h *handler) subscriptionList(w http.ResponseWriter, r *http.Request) {
 	json.OK(w, r, result)
 }
 
-func (h *handler) serve(w http.ResponseWriter, r *http.Request) {
+func (h *handler) serveHandler(w http.ResponseWriter, r *http.Request) {
 	clientIP := request.ClientIP(r)
-	dump, _ := httputil.DumpRequest(r, true)
-	logger.Info("[GoogleReader][UNKNOWN] [ClientIP=%s] URL: %s", clientIP, dump)
-	logger.Error("Call to Google Reader API not implemented yet!!")
+
+	slog.Debug("[GoogleReader] API endpoint not implemented yet",
+		slog.Any("url", r.RequestURI),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
+
 	json.OK(w, r, []string{})
 }
 
-func (h *handler) userInfo(w http.ResponseWriter, r *http.Request) {
+func (h *handler) userInfoHandler(w http.ResponseWriter, r *http.Request) {
 	clientIP := request.ClientIP(r)
-	logger.Info("[GoogleReader][UserInfo] [ClientIP=%s] Sending", clientIP)
+
+	slog.Debug("[GoogleReader] Handle /user-info",
+		slog.String("handler", "userInfoHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
 
 	if err := checkOutputFormat(w, r); err != nil {
-		logger.Error("[GoogleReader][/user-info] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
 
 	user, err := h.store.UserByID(request.UserID(r))
 	if err != nil {
-		logger.Error("[GoogleReader][/user-info] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1083,16 +1247,19 @@ func (h *handler) userInfo(w http.ResponseWriter, r *http.Request) {
 	json.OK(w, r, userInfo)
 }
 
-func (h *handler) streamItemIDs(w http.ResponseWriter, r *http.Request) {
+func (h *handler) streamItemIDsHandler(w http.ResponseWriter, r *http.Request) {
 	userID := request.UserID(r)
 	clientIP := request.ClientIP(r)
 
-	logger.Info("[GoogleReader][/stream/items/ids][ClientIP=%s] Incoming Request for userID #%d", clientIP, userID)
+	slog.Debug("[GoogleReader] Handle /stream/items/ids",
+		slog.String("handler", "streamItemIDsHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+	)
 
 	if err := checkOutputFormat(w, r); err != nil {
-		err := fmt.Errorf("output only as json supported")
-		logger.Error("[GoogleReader][/stream/items/ids] [ClientIP=%s] %v", clientIP, err)
-		json.ServerError(w, r, err)
+		json.ServerError(w, r, fmt.Errorf("googlereader: output only as json supported"))
 		return
 	}
 
@@ -1101,44 +1268,62 @@ func (h *handler) streamItemIDs(w http.ResponseWriter, r *http.Request) {
 		json.ServerError(w, r, err)
 		return
 	}
-	logger.Debug("Request Modifiers: %v", rm)
+
+	slog.Debug("[GoogleReader] Request modifiers",
+		slog.String("handler", "streamItemIDsHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Any("modifiers", rm),
+	)
+
 	if len(rm.Streams) != 1 {
-		err := fmt.Errorf("only one stream type expected")
-		logger.Error("[GoogleReader][/stream/items/ids] [ClientIP=%s] %v", clientIP, err)
-		json.ServerError(w, r, err)
+		json.ServerError(w, r, fmt.Errorf("googlereader: only one stream type expected"))
 		return
 	}
 	switch rm.Streams[0].Type {
 	case ReadingListStream:
-		h.handleReadingListStream(w, r, rm)
+		h.handleReadingListStreamHandler(w, r, rm)
 	case StarredStream:
-		h.handleStarredStream(w, r, rm)
+		h.handleStarredStreamHandler(w, r, rm)
 	case ReadStream:
-		h.handleReadStream(w, r, rm)
+		h.handleReadStreamHandler(w, r, rm)
 	case FeedStream:
-		h.handleFeedStream(w, r, rm)
+		h.handleFeedStreamHandler(w, r, rm)
 	default:
-		dump, _ := httputil.DumpRequest(r, true)
-		logger.Info("[GoogleReader][/stream/items/ids] [ClientIP=%s] Unknown Stream: %s", clientIP, dump)
-		err := fmt.Errorf("unknown stream type")
-		logger.Error("[GoogleReader][/stream/items/ids] [ClientIP=%s] %v", clientIP, err)
-		json.ServerError(w, r, err)
-		return
+		slog.Warn("[GoogleReader] Unknown Stream",
+			slog.String("handler", "streamItemIDsHandler"),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.Any("stream_type", rm.Streams[0].Type),
+		)
+		json.ServerError(w, r, fmt.Errorf("googlereader: unknown stream type %s", rm.Streams[0].Type))
 	}
 }
 
-func (h *handler) handleReadingListStream(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
+func (h *handler) handleReadingListStreamHandler(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
 	clientIP := request.ClientIP(r)
 
+	slog.Debug("[GoogleReader] Handle ReadingListStream",
+		slog.String("handler", "handleReadingListStreamHandler"),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+	)
+
 	builder := h.store.NewEntryQueryBuilder(rm.UserID)
 	for _, s := range rm.ExcludeTargets {
 		switch s.Type {
 		case ReadStream:
 			builder.WithStatus(model.EntryStatusUnread)
 		default:
-			logger.Info("[GoogleReader][ReadingListStreamIDs][ClientIP=%s] xt filter type: %#v", clientIP, s)
+			slog.Warn("[GoogleReader] Unknown ExcludeTargets filter type",
+				slog.String("handler", "handleReadingListStreamHandler"),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+				slog.Any("filter_type", s.Type),
+			)
 		}
 	}
+
 	builder.WithoutStatus(model.EntryStatusRemoved)
 	builder.WithLimit(rm.Count)
 	builder.WithOffset(rm.Offset)
@@ -1152,7 +1337,6 @@ func (h *handler) handleReadingListStream(w http.ResponseWriter, r *http.Request
 
 	rawEntryIDs, err := builder.GetEntryIDs()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#reading-list] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1164,7 +1348,6 @@ func (h *handler) handleReadingListStream(w http.ResponseWriter, r *http.Request
 
 	totalEntries, err := builder.CountEntries()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#reading-list] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1176,9 +1359,7 @@ func (h *handler) handleReadingListStream(w http.ResponseWriter, r *http.Request
 	json.OK(w, r, streamIDResponse{itemRefs, continuation})
 }
 
-func (h *handler) handleStarredStream(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
-	clientIP := request.ClientIP(r)
-
+func (h *handler) handleStarredStreamHandler(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
 	builder := h.store.NewEntryQueryBuilder(rm.UserID)
 	builder.WithoutStatus(model.EntryStatusRemoved)
 	builder.WithStarred(true)
@@ -1194,7 +1375,6 @@ func (h *handler) handleStarredStream(w http.ResponseWriter, r *http.Request, rm
 
 	rawEntryIDs, err := builder.GetEntryIDs()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#starred] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1206,7 +1386,6 @@ func (h *handler) handleStarredStream(w http.ResponseWriter, r *http.Request, rm
 
 	totalEntries, err := builder.CountEntries()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#starred] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1218,9 +1397,7 @@ func (h *handler) handleStarredStream(w http.ResponseWriter, r *http.Request, rm
 	json.OK(w, r, streamIDResponse{itemRefs, continuation})
 }
 
-func (h *handler) handleReadStream(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
-	clientIP := request.ClientIP(r)
-
+func (h *handler) handleReadStreamHandler(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
 	builder := h.store.NewEntryQueryBuilder(rm.UserID)
 	builder.WithoutStatus(model.EntryStatusRemoved)
 	builder.WithStatus(model.EntryStatusRead)
@@ -1236,7 +1413,6 @@ func (h *handler) handleReadStream(w http.ResponseWriter, r *http.Request, rm Re
 
 	rawEntryIDs, err := builder.GetEntryIDs()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#read] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1248,7 +1424,6 @@ func (h *handler) handleReadStream(w http.ResponseWriter, r *http.Request, rm Re
 
 	totalEntries, err := builder.CountEntries()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#read] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1260,11 +1435,9 @@ func (h *handler) handleReadStream(w http.ResponseWriter, r *http.Request, rm Re
 	json.OK(w, r, streamIDResponse{itemRefs, continuation})
 }
 
-func (h *handler) handleFeedStream(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
-	clientIP := request.ClientIP(r)
+func (h *handler) handleFeedStreamHandler(w http.ResponseWriter, r *http.Request, rm RequestModifiers) {
 	feedID, err := strconv.ParseInt(rm.Streams[0].ID, 10, 64)
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#feed] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1284,7 +1457,6 @@ func (h *handler) handleFeedStream(w http.ResponseWriter, r *http.Request, rm Re
 
 	rawEntryIDs, err := builder.GetEntryIDs()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#feed] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}
@@ -1296,7 +1468,6 @@ func (h *handler) handleFeedStream(w http.ResponseWriter, r *http.Request, rm Re
 
 	totalEntries, err := builder.CountEntries()
 	if err != nil {
-		logger.Error("[GoogleReader][/stream/items/ids#feed] [ClientIP=%s] %v", clientIP, err)
 		json.ServerError(w, r, err)
 		return
 	}

internal/googlereader/middleware.go

@@ -8,13 +8,11 @@ import (
 	"crypto/hmac"
 	"crypto/sha1"
 	"encoding/hex"
+	"log/slog"
 	"net/http"
 	"strings"
 
 	"miniflux.app/v2/internal/http/request"
-	"miniflux.app/v2/internal/http/response"
-	"miniflux.app/v2/internal/http/response/json"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/storage"
 )
@@ -27,75 +25,6 @@ func newMiddleware(s *storage.Storage) *middleware {
 	return &middleware{s}
 }
 
-func (m *middleware) clientLogin(w http.ResponseWriter, r *http.Request) {
-	clientIP := request.ClientIP(r)
-	var username, password, output string
-	var integration *model.Integration
-	err := r.ParseForm()
-	if err != nil {
-		logger.Error("[GoogleReader][Login] [ClientIP=%s] Could not parse form", clientIP)
-		json.Unauthorized(w, r)
-		return
-	}
-	username = r.Form.Get("Email")
-	password = r.Form.Get("Passwd")
-	output = r.Form.Get("output")
-
-	if username == "" || password == "" {
-		logger.Error("[GoogleReader][Login] [ClientIP=%s] Empty username or password", clientIP)
-		json.Unauthorized(w, r)
-		return
-	}
-
-	if err = m.store.GoogleReaderUserCheckPassword(username, password); err != nil {
-		logger.Error("[GoogleReader][Login] [ClientIP=%s] Invalid username or password: %s", clientIP, username)
-		json.Unauthorized(w, r)
-		return
-	}
-
-	logger.Info("[GoogleReader][Login] [ClientIP=%s] User authenticated: %s", clientIP, username)
-
-	if integration, err = m.store.GoogleReaderUserGetIntegration(username); err != nil {
-		logger.Error("[GoogleReader][Login] [ClientIP=%s] Could not load integration: %s", clientIP, username)
-		json.Unauthorized(w, r)
-		return
-	}
-
-	m.store.SetLastLogin(integration.UserID)
-
-	token := getAuthToken(integration.GoogleReaderUsername, integration.GoogleReaderPassword)
-	logger.Info("[GoogleReader][Login] [ClientIP=%s] Created token: %s", clientIP, token)
-	result := login{SID: token, LSID: token, Auth: token}
-	if output == "json" {
-		json.OK(w, r, result)
-		return
-	}
-	builder := response.New(w, r)
-	builder.WithHeader("Content-Type", "text/plain; charset=UTF-8")
-	builder.WithBody(result.String())
-	builder.Write()
-}
-
-func (m *middleware) token(w http.ResponseWriter, r *http.Request) {
-	clientIP := request.ClientIP(r)
-
-	if !request.IsAuthenticated(r) {
-		logger.Error("[GoogleReader][Token] [ClientIP=%s] User is not authenticated", clientIP)
-		json.Unauthorized(w, r)
-		return
-	}
-	token := request.GoolgeReaderToken(r)
-	if token == "" {
-		logger.Error("[GoogleReader][Token] [ClientIP=%s] User does not have token: %s", clientIP, request.UserID(r))
-		json.Unauthorized(w, r)
-		return
-	}
-	logger.Info("[GoogleReader][Token] [ClientIP=%s] token: %s", clientIP, token)
-	w.Header().Add("Content-Type", "text/plain; charset=UTF-8")
-	w.WriteHeader(http.StatusOK)
-	w.Write([]byte(token))
-}
-
 func (m *middleware) handleCORS(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Access-Control-Allow-Origin", "*")
@@ -115,15 +44,24 @@ func (m *middleware) apiKeyAuth(next http.Handler) http.Handler {
 
 		var token string
 		if r.Method == http.MethodPost {
-			err := r.ParseForm()
-			if err != nil {
-				logger.Error("[GoogleReader][Login] [ClientIP=%s] Could not parse form", clientIP)
+			if err := r.ParseForm(); err != nil {
+				slog.Warn("[GoogleReader] Could not parse request form data",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+					slog.Any("error", err),
+				)
 				Unauthorized(w, r)
 				return
 			}
+
 			token = r.Form.Get("T")
 			if token == "" {
-				logger.Error("[GoogleReader][Auth] [ClientIP=%s] Post-Form T field is empty", clientIP)
+				slog.Warn("[GoogleReader] Post-Form T field is empty",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+				)
 				Unauthorized(w, r)
 				return
 			}
@@ -131,29 +69,49 @@ func (m *middleware) apiKeyAuth(next http.Handler) http.Handler {
 			authorization := r.Header.Get("Authorization")
 
 			if authorization == "" {
-				logger.Error("[GoogleReader][Auth] [ClientIP=%s] No token provided", clientIP)
+				slog.Warn("[GoogleReader] No token provided",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+				)
 				Unauthorized(w, r)
 				return
 			}
 			fields := strings.Fields(authorization)
 			if len(fields) != 2 {
-				logger.Error("[GoogleReader][Auth] [ClientIP=%s] Authorization header does not have the expected structure GoogleLogin auth=xxxxxx - '%s'", clientIP, authorization)
+				slog.Warn("[GoogleReader] Authorization header does not have the expected GoogleLogin format auth=xxxxxx",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+				)
 				Unauthorized(w, r)
 				return
 			}
 			if fields[0] != "GoogleLogin" {
-				logger.Error("[GoogleReader][Auth] [ClientIP=%s] Authorization header does not begin with GoogleLogin - '%s'", clientIP, authorization)
+				slog.Warn("[GoogleReader] Authorization header does not begin with GoogleLogin",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+				)
 				Unauthorized(w, r)
 				return
 			}
 			auths := strings.Split(fields[1], "=")
 			if len(auths) != 2 {
-				logger.Error("[GoogleReader][Auth] [ClientIP=%s] Authorization header does not have the expected structure GoogleLogin auth=xxxxxx - '%s'", clientIP, authorization)
+				slog.Warn("[GoogleReader] Authorization header does not have the expected GoogleLogin format auth=xxxxxx",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+				)
 				Unauthorized(w, r)
 				return
 			}
 			if auths[0] != "auth" {
-				logger.Error("[GoogleReader][Auth] [ClientIP=%s] Authorization header does not have the expected structure GoogleLogin auth=xxxxxx - '%s'", clientIP, authorization)
+				slog.Warn("[GoogleReader] Authorization header does not have the expected GoogleLogin format auth=xxxxxx",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+				)
 				Unauthorized(w, r)
 				return
 			}
@@ -162,7 +120,12 @@ func (m *middleware) apiKeyAuth(next http.Handler) http.Handler {
 
 		parts := strings.Split(token, "/")
 		if len(parts) != 2 {
-			logger.Error("[GoogleReader][Auth] [ClientIP=%s] Auth token does not have the expected structure username/hash - '%s'", clientIP, token)
+			slog.Warn("[GoogleReader] Auth token does not have the expected structure username/hash",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+				slog.String("token", token),
+			)
 			Unauthorized(w, r)
 			return
 		}
@@ -170,23 +133,54 @@ func (m *middleware) apiKeyAuth(next http.Handler) http.Handler {
 		var user *model.User
 		var err error
 		if integration, err = m.store.GoogleReaderUserGetIntegration(parts[0]); err != nil {
-			logger.Error("[GoogleReader][Auth] [ClientIP=%s] token: %s", clientIP, token)
-			logger.Error("[GoogleReader][Auth] [ClientIP=%s] No user found with the given google reader username: %s", clientIP, parts[0])
+			slog.Warn("[GoogleReader] No user found with the given Google Reader username",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+				slog.Any("error", err),
+			)
 			Unauthorized(w, r)
 			return
 		}
 		expectedToken := getAuthToken(integration.GoogleReaderUsername, integration.GoogleReaderPassword)
 		if expectedToken != token {
-			logger.Error("[GoogleReader][Auth] [ClientIP=%s] Token does not match: %s", clientIP, token)
+			slog.Warn("[GoogleReader] Token does not match",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
 			Unauthorized(w, r)
 			return
 		}
 		if user, err = m.store.UserByID(integration.UserID); err != nil {
-			logger.Error("[GoogleReader][Auth] [ClientIP=%s] No user found with the userID: %d", clientIP, integration.UserID)
+			slog.Error("[GoogleReader] Unable to fetch user from database",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+				slog.Any("error", err),
+			)
 			Unauthorized(w, r)
 			return
 		}
 
+		if user == nil {
+			slog.Warn("[GoogleReader] No user found with the given Google Reader credentials",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("user_agent", r.UserAgent()),
+			)
+			Unauthorized(w, r)
+			return
+		}
+
+		slog.Info("[GoogleReader] User authenticated successfully",
+			slog.Bool("authentication_successful", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.Int64("user_id", user.ID),
+			slog.String("username", user.Username),
+		)
+
 		m.store.SetLastLogin(integration.UserID)
 
 		ctx := r.Context()

internal/googlereader/response.go

@@ -8,7 +8,6 @@ import (
 	"net/http"
 
 	"miniflux.app/v2/internal/http/response"
-	"miniflux.app/v2/internal/logger"
 )
 
 type login struct {
@@ -122,8 +121,6 @@ type contentItemOrigin struct {
 
 // Unauthorized sends a not authorized error to the client.
 func Unauthorized(w http.ResponseWriter, r *http.Request) {
-	logger.Error("[HTTP:Unauthorized] %s", r.URL)
-
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusUnauthorized)
 	builder.WithHeader("Content-Type", "text/plain")
@@ -134,8 +131,6 @@ func Unauthorized(w http.ResponseWriter, r *http.Request) {
 
 // OK sends a ok response to the client.
 func OK(w http.ResponseWriter, r *http.Request) {
-	logger.Info("[HTTP:OK] %s", r.URL)
-
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusOK)
 	builder.WithHeader("Content-Type", "text/plain")

internal/http/client/client.go

@@ -7,19 +7,16 @@ import (
 	"bytes"
 	"crypto/tls"
 	"crypto/x509"
-	"encoding/json"
 	"fmt"
 	"io"
+	"log/slog"
 	"net"
 	"net/http"
 	"net/url"
-	"strings"
 	"time"
 
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/errors"
-	"miniflux.app/v2/internal/logger"
-	"miniflux.app/v2/internal/timer"
 )
 
 const (
@@ -74,28 +71,6 @@ func NewClientWithConfig(url string, opts *config.Options) *Client {
 	}
 }
 
-func (c *Client) String() string {
-	etagHeader := c.requestEtagHeader
-	if c.requestEtagHeader == "" {
-		etagHeader = "None"
-	}
-
-	lastModifiedHeader := c.requestLastModifiedHeader
-	if c.requestLastModifiedHeader == "" {
-		lastModifiedHeader = "None"
-	}
-
-	return fmt.Sprintf(
-		`InputURL=%q ETag=%s LastMod=%s Auth=%v UserAgent=%q Verify=%v`,
-		c.inputURL,
-		etagHeader,
-		lastModifiedHeader,
-		c.requestAuthorizationHeader != "" || (c.requestUsername != "" && c.requestPassword != ""),
-		c.requestUserAgent,
-		!c.AllowSelfSignedCertificates,
-	)
-}
-
 // WithCredentials defines the username/password for HTTP Basic authentication.
 func (c *Client) WithCredentials(username, password string) *Client {
 	if username != "" && password != "" {
@@ -105,12 +80,6 @@ func (c *Client) WithCredentials(username, password string) *Client {
 	return c
 }
 
-// WithAuthorization defines the authorization HTTP header value.
-func (c *Client) WithAuthorization(authorization string) *Client {
-	c.requestAuthorizationHeader = authorization
-	return c
-}
-
 // WithCustomHeaders defines custom HTTP headers.
 func (c *Client) WithCustomHeaders(customHeaders map[string]string) *Client {
 	c.customHeaders = customHeaders
@@ -162,55 +131,21 @@ func (c *Client) Get() (*Response, error) {
 	return c.executeRequest(request)
 }
 
-// PostForm performs a POST HTTP request with form encoded values.
-func (c *Client) PostForm(values url.Values) (*Response, error) {
-	request, err := c.buildRequest(http.MethodPost, strings.NewReader(values.Encode()))
-	if err != nil {
-		return nil, err
-	}
-
-	request.Header.Add("Content-Type", "application/x-www-form-urlencoded")
-	return c.executeRequest(request)
-}
-
-// PostJSON performs a POST HTTP request with a JSON payload.
-func (c *Client) PostJSON(data interface{}) (*Response, error) {
-	b, err := json.Marshal(data)
-	if err != nil {
-		return nil, err
-	}
-
-	request, err := c.buildRequest(http.MethodPost, bytes.NewReader(b))
-	if err != nil {
-		return nil, err
-	}
-
-	request.Header.Add("Content-Type", "application/json")
-	return c.executeRequest(request)
-}
-
-// PatchJSON performs a Patch HTTP request with a JSON payload.
-func (c *Client) PatchJSON(data interface{}) (*Response, error) {
-	b, err := json.Marshal(data)
-	if err != nil {
-		return nil, err
-	}
-
-	request, err := c.buildRequest(http.MethodPatch, bytes.NewReader(b))
-	if err != nil {
-		return nil, err
-	}
-
-	request.Header.Add("Content-Type", "application/json")
-	return c.executeRequest(request)
-}
-
 func (c *Client) executeRequest(request *http.Request) (*Response, error) {
-	defer timer.ExecutionTime(time.Now(), fmt.Sprintf("[HttpClient] inputURL=%s", c.inputURL))
-
-	logger.Debug("[HttpClient:Before] Method=%s %s",
-		request.Method,
-		c.String(),
+	startTime := time.Now()
+
+	slog.Debug("Executing outgoing HTTP request",
+		slog.Group("request",
+			slog.String("method", request.Method),
+			slog.String("url", request.URL.String()),
+			slog.String("user_agent", request.UserAgent()),
+			slog.Bool("is_authenticated", c.requestAuthorizationHeader != "" || (c.requestUsername != "" && c.requestPassword != "")),
+			slog.Bool("has_cookie", c.requestCookie != ""),
+			slog.Bool("with_redirects", !c.doNotFollowRedirects),
+			slog.Bool("with_proxy", c.useProxy),
+			slog.String("proxy_url", c.ClientProxyURL),
+			slog.Bool("with_caching_headers", c.requestEtagHeader != "" || c.requestLastModifiedHeader != ""),
+		),
 	)
 
 	client := c.buildClient()
@@ -257,15 +192,32 @@ func (c *Client) executeRequest(request *http.Request) (*Response, error) {
 		ContentLength: resp.ContentLength,
 	}
 
-	logger.Debug("[HttpClient:After] Method=%s %s; Response => %s",
-		request.Method,
-		c.String(),
-		response,
+	slog.Debug("Completed outgoing HTTP request",
+		slog.Duration("duration", time.Since(startTime)),
+		slog.Group("request",
+			slog.String("method", request.Method),
+			slog.String("url", request.URL.String()),
+			slog.String("user_agent", request.UserAgent()),
+			slog.Bool("is_authenticated", c.requestAuthorizationHeader != "" || (c.requestUsername != "" && c.requestPassword != "")),
+			slog.Bool("has_cookie", c.requestCookie != ""),
+			slog.Bool("with_redirects", !c.doNotFollowRedirects),
+			slog.Bool("with_proxy", c.useProxy),
+			slog.String("proxy_url", c.ClientProxyURL),
+			slog.Bool("with_caching_headers", c.requestEtagHeader != "" || c.requestLastModifiedHeader != ""),
+		),
+		slog.Group("response",
+			slog.Int("status_code", response.StatusCode),
+			slog.String("effective_url", response.EffectiveURL),
+			slog.String("content_type", response.ContentType),
+			slog.Int64("content_length", response.ContentLength),
+			slog.String("last_modified", response.LastModified),
+			slog.String("etag", response.ETag),
+			slog.String("expires", response.Expires),
+		),
 	)
 
 	// Ignore caching headers for feeds that do not want any cache.
 	if resp.Header.Get("Expires") == "0" {
-		logger.Debug("[HttpClient] Ignore caching headers for %q", response.EffectiveURL)
 		response.ETag = ""
 		response.LastModified = ""
 	}
@@ -323,9 +275,11 @@ func (c *Client) buildClient() http.Client {
 	if c.useProxy && c.ClientProxyURL != "" {
 		proxyURL, err := url.Parse(c.ClientProxyURL)
 		if err != nil {
-			logger.Error("[HttpClient] Proxy URL error: %v", err)
+			slog.Error("Unable to parse proxy URL",
+				slog.String("proxy_url", c.ClientProxyURL),
+				slog.Any("error", err),
+			)
 		} else {
-			logger.Debug("[HttpClient] Use proxy: %s", proxyURL)
 			transport.Proxy = http.ProxyURL(proxyURL)
 		}
 	}

internal/http/response/builder.go

@@ -8,11 +8,10 @@ import (
 	"compress/gzip"
 	"fmt"
 	"io"
+	"log/slog"
 	"net/http"
 	"strings"
 	"time"
-
-	"miniflux.app/v2/internal/logger"
 )
 
 const compressionThreshold = 1024
@@ -91,7 +90,7 @@ func (b *Builder) Write() {
 		b.writeHeaders()
 		_, err := io.Copy(b.w, v)
 		if err != nil {
-			logger.Error("%v", err)
+			slog.Error("Unable to write response body", slog.Any("error", err))
 		}
 	}
 }

internal/http/response/html/html.go

@@ -4,10 +4,11 @@
 package html // import "miniflux.app/v2/internal/http/response/html"
 
 import (
+	"log/slog"
 	"net/http"
 
+	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response"
-	"miniflux.app/v2/internal/logger"
 )
 
 // OK creates a new HTML response with a 200 status code.
@@ -21,7 +22,18 @@ func OK(w http.ResponseWriter, r *http.Request, body interface{}) {
 
 // ServerError sends an internal error to the client.
 func ServerError(w http.ResponseWriter, r *http.Request, err error) {
-	logger.Error("[HTTP:Internal Server Error] %s => %v", r.URL, err)
+	slog.Error(http.StatusText(http.StatusInternalServerError),
+		slog.Any("error", err),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusInternalServerError),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusInternalServerError)
@@ -34,7 +46,18 @@ func ServerError(w http.ResponseWriter, r *http.Request, err error) {
 
 // BadRequest sends a bad request error to the client.
 func BadRequest(w http.ResponseWriter, r *http.Request, err error) {
-	logger.Error("[HTTP:Bad Request] %s => %v", r.URL, err)
+	slog.Warn(http.StatusText(http.StatusBadRequest),
+		slog.Any("error", err),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusBadRequest),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusBadRequest)
@@ -47,7 +70,17 @@ func BadRequest(w http.ResponseWriter, r *http.Request, err error) {
 
 // Forbidden sends a forbidden error to the client.
 func Forbidden(w http.ResponseWriter, r *http.Request) {
-	logger.Error("[HTTP:Forbidden] %s", r.URL)
+	slog.Warn(http.StatusText(http.StatusForbidden),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusForbidden),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusForbidden)
@@ -59,7 +92,17 @@ func Forbidden(w http.ResponseWriter, r *http.Request) {
 
 // NotFound sends a page not found error to the client.
 func NotFound(w http.ResponseWriter, r *http.Request) {
-	logger.Error("[HTTP:Not Found] %s", r.URL)
+	slog.Warn(http.StatusText(http.StatusNotFound),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusNotFound),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusNotFound)
@@ -76,7 +119,17 @@ func Redirect(w http.ResponseWriter, r *http.Request, uri string) {
 
 // RequestedRangeNotSatisfiable sends a range not satisfiable error to the client.
 func RequestedRangeNotSatisfiable(w http.ResponseWriter, r *http.Request, contentRange string) {
-	logger.Error("[HTTP:Range Not Satisfiable] %s", r.URL)
+	slog.Warn(http.StatusText(http.StatusRequestedRangeNotSatisfiable),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusRequestedRangeNotSatisfiable),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusRequestedRangeNotSatisfiable)

internal/http/response/json/json.go

@@ -6,10 +6,11 @@ package json // import "miniflux.app/v2/internal/http/response/json"
 import (
 	"encoding/json"
 	"errors"
+	"log/slog"
 	"net/http"
 
+	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response"
-	"miniflux.app/v2/internal/logger"
 )
 
 const contentTypeHeader = `application/json`
@@ -48,7 +49,18 @@ func Accepted(w http.ResponseWriter, r *http.Request) {
 
 // ServerError sends an internal error to the client.
 func ServerError(w http.ResponseWriter, r *http.Request, err error) {
-	logger.Error("[HTTP:Internal Server Error] %s => %v", r.URL, err)
+	slog.Error(http.StatusText(http.StatusInternalServerError),
+		slog.Any("error", err),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusInternalServerError),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusInternalServerError)
@@ -59,7 +71,18 @@ func ServerError(w http.ResponseWriter, r *http.Request, err error) {
 
 // BadRequest sends a bad request error to the client.
 func BadRequest(w http.ResponseWriter, r *http.Request, err error) {
-	logger.Error("[HTTP:Bad Request] %s => %v", r.URL, err)
+	slog.Warn(http.StatusText(http.StatusBadRequest),
+		slog.Any("error", err),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusBadRequest),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusBadRequest)
@@ -70,7 +93,17 @@ func BadRequest(w http.ResponseWriter, r *http.Request, err error) {
 
 // Unauthorized sends a not authorized error to the client.
 func Unauthorized(w http.ResponseWriter, r *http.Request) {
-	logger.Error("[HTTP:Unauthorized] %s", r.URL)
+	slog.Warn(http.StatusText(http.StatusUnauthorized),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusUnauthorized),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusUnauthorized)
@@ -81,7 +114,17 @@ func Unauthorized(w http.ResponseWriter, r *http.Request) {
 
 // Forbidden sends a forbidden error to the client.
 func Forbidden(w http.ResponseWriter, r *http.Request) {
-	logger.Error("[HTTP:Forbidden] %s", r.URL)
+	slog.Warn(http.StatusText(http.StatusForbidden),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusForbidden),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusForbidden)
@@ -92,7 +135,17 @@ func Forbidden(w http.ResponseWriter, r *http.Request) {
 
 // NotFound sends a page not found error to the client.
 func NotFound(w http.ResponseWriter, r *http.Request) {
-	logger.Error("[HTTP:Not Found] %s", r.URL)
+	slog.Warn(http.StatusText(http.StatusNotFound),
+		slog.String("client_ip", request.ClientIP(r)),
+		slog.Group("request",
+			slog.String("method", r.Method),
+			slog.String("uri", r.RequestURI),
+			slog.String("user_agent", r.UserAgent()),
+		),
+		slog.Group("response",
+			slog.Int("status_code", http.StatusNotFound),
+		),
+	)
 
 	builder := response.New(w, r)
 	builder.WithStatus(http.StatusNotFound)
@@ -112,7 +165,7 @@ func toJSONError(err error) []byte {
 func toJSON(v interface{}) []byte {
 	b, err := json.Marshal(v)
 	if err != nil {
-		logger.Error("[HTTP:JSON] %v", err)
+		slog.Error("Unable to marshal JSON response", slog.Any("error", err))
 		return []byte("")
 	}
 

internal/http/route/route.go

@@ -7,14 +7,13 @@ import (
 	"strconv"
 
 	"github.com/gorilla/mux"
-	"miniflux.app/v2/internal/logger"
 )
 
 // Path returns the defined route based on given arguments.
-func Path(router *mux.Router, name string, args ...interface{}) string {
+func Path(router *mux.Router, name string, args ...any) string {
 	route := router.Get(name)
 	if route == nil {
-		logger.Fatal("[Route] Route not found: %s", name)
+		panic("route not found: " + name)
 	}
 
 	var pairs []string
@@ -29,7 +28,7 @@ func Path(router *mux.Router, name string, args ...interface{}) string {
 
 	result, err := route.URLPath(pairs...)
 	if err != nil {
-		logger.Fatal("[Route] %v", err)
+		panic(err)
 	}
 
 	return result.String()

internal/http/server/httpd.go

@@ -5,6 +5,8 @@ package httpd // import "miniflux.app/v2/internal/http/server"
 
 import (
 	"crypto/tls"
+	"fmt"
+	"log/slog"
 	"net"
 	"net/http"
 	"os"
@@ -17,7 +19,6 @@ import (
 	"miniflux.app/v2/internal/fever"
 	"miniflux.app/v2/internal/googlereader"
 	"miniflux.app/v2/internal/http/request"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/ui"
 	"miniflux.app/v2/internal/version"
@@ -66,12 +67,12 @@ func startSystemdSocketServer(server *http.Server) {
 		f := os.NewFile(3, "systemd socket")
 		listener, err := net.FileListener(f)
 		if err != nil {
-			logger.Fatal(`Unable to create listener from systemd socket: %v`, err)
+			printErrorAndExit(`Unable to create listener from systemd socket: %v`, err)
 		}
 
-		logger.Info(`Listening on systemd socket`)
+		slog.Info(`Starting server using systemd socket`)
 		if err := server.Serve(listener); err != http.ErrServerClosed {
-			logger.Fatal(`Server failed to start: %v`, err)
+			printErrorAndExit(`Server failed to start: %v`, err)
 		}
 	}()
 }
@@ -82,17 +83,17 @@ func startUnixSocketServer(server *http.Server, socketFile string) {
 	go func(sock string) {
 		listener, err := net.Listen("unix", sock)
 		if err != nil {
-			logger.Fatal(`Server failed to start: %v`, err)
+			printErrorAndExit(`Server failed to start: %v`, err)
 		}
 		defer listener.Close()
 
 		if err := os.Chmod(sock, 0666); err != nil {
-			logger.Fatal(`Unable to change socket permission: %v`, err)
+			printErrorAndExit(`Unable to change socket permission: %v`, err)
 		}
 
-		logger.Info(`Listening on Unix socket %q`, sock)
+		slog.Info("Starting server using a Unix socket", slog.String("socket", sock))
 		if err := server.Serve(listener); err != http.ErrServerClosed {
-			logger.Fatal(`Server failed to start: %v`, err)
+			printErrorAndExit(`Server failed to start: %v`, err)
 		}
 	}(socketFile)
 }
@@ -137,9 +138,12 @@ func startAutoCertTLSServer(server *http.Server, certDomain string, store *stora
 	go s.ListenAndServe()
 
 	go func() {
-		logger.Info(`Listening on %q by using auto-configured certificate for %q`, server.Addr, certDomain)
+		slog.Info("Starting TLS server using automatic certificate management",
+			slog.String("listen_address", server.Addr),
+			slog.String("domain", certDomain),
+		)
 		if err := server.ListenAndServeTLS("", ""); err != http.ErrServerClosed {
-			logger.Fatal(`Server failed to start: %v`, err)
+			printErrorAndExit(`Server failed to start: %v`, err)
 		}
 	}()
 }
@@ -147,18 +151,24 @@ func startAutoCertTLSServer(server *http.Server, certDomain string, store *stora
 func startTLSServer(server *http.Server, certFile, keyFile string) {
 	server.TLSConfig = tlsConfig()
 	go func() {
-		logger.Info(`Listening on %q by using certificate %q and key %q`, server.Addr, certFile, keyFile)
+		slog.Info("Starting TLS server using a certificate",
+			slog.String("listen_address", server.Addr),
+			slog.String("cert_file", certFile),
+			slog.String("key_file", keyFile),
+		)
 		if err := server.ListenAndServeTLS(certFile, keyFile); err != http.ErrServerClosed {
-			logger.Fatal(`Server failed to start: %v`, err)
+			printErrorAndExit(`Server failed to start: %v`, err)
 		}
 	}()
 }
 
 func startHTTPServer(server *http.Server) {
 	go func() {
-		logger.Info(`Listening on %q without TLS`, server.Addr)
+		slog.Info("Starting HTTP server",
+			slog.String("listen_address", server.Addr),
+		)
 		if err := server.ListenAndServe(); err != http.ErrServerClosed {
-			logger.Fatal(`Server failed to start: %v`, err)
+			printErrorAndExit(`Server failed to start: %v`, err)
 		}
 	}()
 }
@@ -206,7 +216,11 @@ func setupHandler(store *storage.Storage, pool *worker.Pool) *mux.Router {
 
 				// Returns a 404 if the client is not authorized to access the metrics endpoint.
 				if route.GetName() == "metrics" && !isAllowedToAccessMetricsEndpoint(r) {
-					logger.Error(`[Metrics] [ClientIP=%s] Client not allowed (%s)`, request.ClientIP(r), r.RemoteAddr)
+					slog.Warn("Authentication failed while accessing the metrics endpoint",
+						slog.String("client_ip", request.ClientIP(r)),
+						slog.String("client_user_agent", r.UserAgent()),
+						slog.String("client_remote_addr", r.RemoteAddr),
+					)
 					http.NotFound(w, r)
 					return
 				}
@@ -220,21 +234,37 @@ func setupHandler(store *storage.Storage, pool *worker.Pool) *mux.Router {
 }
 
 func isAllowedToAccessMetricsEndpoint(r *http.Request) bool {
+	clientIP := request.ClientIP(r)
+
 	if config.Opts.MetricsUsername() != "" && config.Opts.MetricsPassword() != "" {
-		clientIP := request.ClientIP(r)
 		username, password, authOK := r.BasicAuth()
 		if !authOK {
-			logger.Info("[Metrics] [ClientIP=%s] No authentication header sent", clientIP)
+			slog.Warn("Metrics endpoint accessed without authentication header",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("client_user_agent", r.UserAgent()),
+				slog.String("client_remote_addr", r.RemoteAddr),
+			)
 			return false
 		}
 
 		if username == "" || password == "" {
-			logger.Info("[Metrics] [ClientIP=%s] Empty username or password", clientIP)
+			slog.Warn("Metrics endpoint accessed with empty username or password",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("client_user_agent", r.UserAgent()),
+				slog.String("client_remote_addr", r.RemoteAddr),
+			)
 			return false
 		}
 
 		if username != config.Opts.MetricsUsername() || password != config.Opts.MetricsPassword() {
-			logger.Error("[Metrics] [ClientIP=%s] Invalid username or password", clientIP)
+			slog.Warn("Metrics endpoint accessed with invalid username or password",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("client_user_agent", r.UserAgent()),
+				slog.String("client_remote_addr", r.RemoteAddr),
+			)
 			return false
 		}
 	}
@@ -242,7 +272,14 @@ func isAllowedToAccessMetricsEndpoint(r *http.Request) bool {
 	for _, cidr := range config.Opts.MetricsAllowedNetworks() {
 		_, network, err := net.ParseCIDR(cidr)
 		if err != nil {
-			logger.Fatal(`[Metrics] Unable to parse CIDR %v`, err)
+			slog.Error("Metrics endpoint accessed with invalid CIDR",
+				slog.Bool("authentication_failed", true),
+				slog.String("client_ip", clientIP),
+				slog.String("client_user_agent", r.UserAgent()),
+				slog.String("client_remote_addr", r.RemoteAddr),
+				slog.String("cidr", cidr),
+			)
+			return false
 		}
 
 		// We use r.RemoteAddr in this case because HTTP headers like X-Forwarded-For can be easily spoofed.
@@ -254,3 +291,10 @@ func isAllowedToAccessMetricsEndpoint(r *http.Request) bool {
 
 	return false
 }
+
+func printErrorAndExit(format string, a ...any) {
+	message := fmt.Sprintf(format, a...)
+	slog.Error(message)
+	fmt.Fprintf(os.Stderr, "%v\n", message)
+	os.Exit(1)
+}

internal/http/server/middleware.go

@@ -5,11 +5,12 @@ package httpd // import "miniflux.app/v2/internal/http/server"
 
 import (
 	"context"
+	"log/slog"
 	"net/http"
+	"time"
 
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/http/request"
-	"miniflux.app/v2/internal/logger"
 )
 
 func middleware(next http.Handler) http.Handler {
@@ -22,12 +23,18 @@ func middleware(next http.Handler) http.Handler {
 			config.Opts.HTTPS = true
 		}
 
-		protocol := "HTTP"
-		if config.Opts.HTTPS {
-			protocol = "HTTPS"
-		}
-
-		logger.Debug("[%s] %s %s %s", protocol, clientIP, r.Method, r.RequestURI)
+		t1 := time.Now()
+		defer func() {
+			slog.Debug("Incoming request",
+				slog.String("client_ip", clientIP),
+				slog.Group("request",
+					slog.String("method", r.Method),
+					slog.String("uri", r.RequestURI),
+					slog.String("protocol", r.Proto),
+					slog.Duration("execution_time", time.Since(t1)),
+				),
+			)
+		}()
 
 		if config.Opts.HTTPS && config.Opts.HasHSTS() {
 			w.Header().Set("Strict-Transport-Security", "max-age=31536000")

internal/integration/integration.go

@@ -4,6 +4,8 @@
 package integration // import "miniflux.app/v2/internal/integration"
 
 import (
+	"log/slog"
+
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/integration/apprise"
 	"miniflux.app/v2/internal/integration/espial"
@@ -20,160 +22,269 @@ import (
 	"miniflux.app/v2/internal/integration/telegrambot"
 	"miniflux.app/v2/internal/integration/wallabag"
 	"miniflux.app/v2/internal/integration/webhook"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 )
 
 // SendEntry sends the entry to third-party providers when the user click on "Save".
-func SendEntry(entry *model.Entry, integration *model.Integration) {
-	if integration.PinboardEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Pinboard", entry.ID, entry.URL, integration.UserID)
+func SendEntry(entry *model.Entry, userIntegrations *model.Integration) {
+	if userIntegrations.PinboardEnabled {
+		slog.Debug("Sending entry to Pinboard",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
-		client := pinboard.NewClient(integration.PinboardToken)
+		client := pinboard.NewClient(userIntegrations.PinboardToken)
 		err := client.CreateBookmark(
 			entry.URL,
 			entry.Title,
-			integration.PinboardTags,
-			integration.PinboardMarkAsUnread,
+			userIntegrations.PinboardTags,
+			userIntegrations.PinboardMarkAsUnread,
 		)
 
 		if err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Pinboard",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.InstapaperEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Instapaper", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.InstapaperEnabled {
+		slog.Debug("Sending entry to Instapaper",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
-		client := instapaper.NewClient(integration.InstapaperUsername, integration.InstapaperPassword)
+		client := instapaper.NewClient(userIntegrations.InstapaperUsername, userIntegrations.InstapaperPassword)
 		if err := client.AddURL(entry.URL, entry.Title); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Instapaper",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.WallabagEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Wallabag", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.WallabagEnabled {
+		slog.Debug("Sending entry to Wallabag",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := wallabag.NewClient(
-			integration.WallabagURL,
-			integration.WallabagClientID,
-			integration.WallabagClientSecret,
-			integration.WallabagUsername,
-			integration.WallabagPassword,
-			integration.WallabagOnlyURL,
+			userIntegrations.WallabagURL,
+			userIntegrations.WallabagClientID,
+			userIntegrations.WallabagClientSecret,
+			userIntegrations.WallabagUsername,
+			userIntegrations.WallabagPassword,
+			userIntegrations.WallabagOnlyURL,
 		)
 
 		if err := client.CreateEntry(entry.URL, entry.Title, entry.Content); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Wallabag",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.NotionEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Notion", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.NotionEnabled {
+		slog.Debug("Sending entry to Notion",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := notion.NewClient(
-			integration.NotionToken,
-			integration.NotionPageID,
+			userIntegrations.NotionToken,
+			userIntegrations.NotionPageID,
 		)
 		if err := client.UpdateDocument(entry.URL, entry.Title); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Notion",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.NunuxKeeperEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to NunuxKeeper", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.NunuxKeeperEnabled {
+		slog.Debug("Sending entry to NunuxKeeper",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := nunuxkeeper.NewClient(
-			integration.NunuxKeeperURL,
-			integration.NunuxKeeperAPIKey,
+			userIntegrations.NunuxKeeperURL,
+			userIntegrations.NunuxKeeperAPIKey,
 		)
 
 		if err := client.AddEntry(entry.URL, entry.Title, entry.Content); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to NunuxKeeper",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.EspialEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Espial", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.EspialEnabled {
+		slog.Debug("Sending entry to Espial",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := espial.NewClient(
-			integration.EspialURL,
-			integration.EspialAPIKey,
+			userIntegrations.EspialURL,
+			userIntegrations.EspialAPIKey,
 		)
 
-		if err := client.CreateLink(entry.URL, entry.Title, integration.EspialTags); err != nil {
-			logger.Error("[Integration] Unable to send entry #%d to Espial for user #%d: %v", entry.ID, integration.UserID, err)
+		if err := client.CreateLink(entry.URL, entry.Title, userIntegrations.EspialTags); err != nil {
+			slog.Error("Unable to send entry to Espial",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.PocketEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Pocket", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.PocketEnabled {
+		slog.Debug("Sending entry to Pocket",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
-		client := pocket.NewClient(config.Opts.PocketConsumerKey(integration.PocketConsumerKey), integration.PocketAccessToken)
+		client := pocket.NewClient(config.Opts.PocketConsumerKey(userIntegrations.PocketConsumerKey), userIntegrations.PocketAccessToken)
 		if err := client.AddURL(entry.URL, entry.Title); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Pocket",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.LinkdingEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Linkding", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.LinkdingEnabled {
+		slog.Debug("Sending entry to Linkding",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := linkding.NewClient(
-			integration.LinkdingURL,
-			integration.LinkdingAPIKey,
-			integration.LinkdingTags,
-			integration.LinkdingMarkAsUnread,
+			userIntegrations.LinkdingURL,
+			userIntegrations.LinkdingAPIKey,
+			userIntegrations.LinkdingTags,
+			userIntegrations.LinkdingMarkAsUnread,
 		)
 		if err := client.CreateBookmark(entry.URL, entry.Title); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Linkding",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.ReadwiseEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Readwise Reader", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.ReadwiseEnabled {
+		slog.Debug("Sending entry to Readwise",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := readwise.NewClient(
-			integration.ReadwiseAPIKey,
+			userIntegrations.ReadwiseAPIKey,
 		)
 
 		if err := client.CreateDocument(entry.URL); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Readwise",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.ShioriEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Shiori", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.ShioriEnabled {
+		slog.Debug("Sending entry to Shiori",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := shiori.NewClient(
-			integration.ShioriURL,
-			integration.ShioriUsername,
-			integration.ShioriPassword,
+			userIntegrations.ShioriURL,
+			userIntegrations.ShioriUsername,
+			userIntegrations.ShioriPassword,
 		)
 
 		if err := client.CreateBookmark(entry.URL, entry.Title); err != nil {
-			logger.Error("[Integration] Unable to send entry #%d to Shiori for user #%d: %v", entry.ID, integration.UserID, err)
+			slog.Error("Unable to send entry to Shiori",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.ShaarliEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Shaarli", entry.ID, entry.URL, integration.UserID)
+	if userIntegrations.ShaarliEnabled {
+		slog.Debug("Sending entry to Shaarli",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+		)
 
 		client := shaarli.NewClient(
-			integration.ShaarliURL,
-			integration.ShaarliAPISecret,
+			userIntegrations.ShaarliURL,
+			userIntegrations.ShaarliAPISecret,
 		)
 
 		if err := client.CreateLink(entry.URL, entry.Title); err != nil {
-			logger.Error("[Integration] Unable to send entry #%d to Shaarli for user #%d: %v", entry.ID, integration.UserID, err)
+			slog.Error("Unable to send entry to Shaarli",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
-	if integration.WebhookEnabled {
-		logger.Debug("[Integration] Sending entry #%d %q for user #%d to Webhook URL: %s", entry.ID, entry.URL, integration.UserID, integration.WebhookURL)
+	if userIntegrations.WebhookEnabled {
+		slog.Debug("Sending entry to Webhook",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+			slog.String("webhook_url", userIntegrations.WebhookURL),
+		)
 
-		webhookClient := webhook.NewClient(integration.WebhookURL, integration.WebhookSecret)
+		webhookClient := webhook.NewClient(userIntegrations.WebhookURL, userIntegrations.WebhookSecret)
 		if err := webhookClient.SendSaveEntryWebhookEvent(entry); err != nil {
-			logger.Error("[Integration] UserID #%d: %v", integration.UserID, err)
+			slog.Error("Unable to send entry to Webhook",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.String("webhook_url", userIntegrations.WebhookURL),
+				slog.Any("error", err),
+			)
 		}
 	}
 }
@@ -181,20 +292,47 @@ func SendEntry(entry *model.Entry, integration *model.Integration) {
 // PushEntries pushes a list of entries to activated third-party providers during feed refreshes.
 func PushEntries(feed *model.Feed, entries model.Entries, userIntegrations *model.Integration) {
 	if userIntegrations.MatrixBotEnabled {
-		logger.Debug("[Integration] Sending %d entries for user #%d to Matrix", len(entries), userIntegrations.UserID)
+		slog.Debug("Sending new entries to Matrix",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int("nb_entries", len(entries)),
+			slog.Int64("feed_id", feed.ID),
+		)
 
-		err := matrixbot.PushEntries(feed, entries, userIntegrations.MatrixBotURL, userIntegrations.MatrixBotUser, userIntegrations.MatrixBotPassword, userIntegrations.MatrixBotChatID)
+		err := matrixbot.PushEntries(
+			feed,
+			entries,
+			userIntegrations.MatrixBotURL,
+			userIntegrations.MatrixBotUser,
+			userIntegrations.MatrixBotPassword,
+			userIntegrations.MatrixBotChatID,
+		)
 		if err != nil {
-			logger.Error("[Integration] push entries to matrix bot failed: %v", err)
+			slog.Error("Unable to send new entries to Matrix",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int("nb_entries", len(entries)),
+				slog.Int64("feed_id", feed.ID),
+				slog.Any("error", err),
+			)
 		}
 	}
 
 	if userIntegrations.WebhookEnabled {
-		logger.Debug("[Integration] Sending %d entries for user #%d to Webhook URL: %s", len(entries), userIntegrations.UserID, userIntegrations.WebhookURL)
+		slog.Debug("Sending new entries to Webhook",
+			slog.Int64("user_id", userIntegrations.UserID),
+			slog.Int("nb_entries", len(entries)),
+			slog.Int64("feed_id", feed.ID),
+			slog.String("webhook_url", userIntegrations.WebhookURL),
+		)
 
 		webhookClient := webhook.NewClient(userIntegrations.WebhookURL, userIntegrations.WebhookSecret)
 		if err := webhookClient.SendNewEntriesWebhookEvent(feed, entries); err != nil {
-			logger.Error("[Integration] sending entries to webhook failed: %v", err)
+			slog.Debug("Unable to send new entries to Webhook",
+				slog.Int64("user_id", userIntegrations.UserID),
+				slog.Int("nb_entries", len(entries)),
+				slog.Int64("feed_id", feed.ID),
+				slog.String("webhook_url", userIntegrations.WebhookURL),
+				slog.Any("error", err),
+			)
 		}
 	}
 
@@ -202,7 +340,11 @@ func PushEntries(feed *model.Feed, entries model.Entries, userIntegrations *mode
 	if userIntegrations.TelegramBotEnabled || userIntegrations.AppriseEnabled {
 		for _, entry := range entries {
 			if userIntegrations.TelegramBotEnabled {
-				logger.Debug("[Integration] Sending entry %q for user #%d to Telegram", entry.URL, userIntegrations.UserID)
+				slog.Debug("Sending a new entry to Telegram",
+					slog.Int64("user_id", userIntegrations.UserID),
+					slog.Int64("entry_id", entry.ID),
+					slog.String("entry_url", entry.URL),
+				)
 
 				if err := telegrambot.PushEntry(
 					feed,
@@ -213,12 +355,21 @@ func PushEntries(feed *model.Feed, entries model.Entries, userIntegrations *mode
 					userIntegrations.TelegramBotDisableWebPagePreview,
 					userIntegrations.TelegramBotDisableNotification,
 				); err != nil {
-					logger.Error("[Integration] %v", err)
+					slog.Error("Unable to send entry to Telegram",
+						slog.Int64("user_id", userIntegrations.UserID),
+						slog.Int64("entry_id", entry.ID),
+						slog.String("entry_url", entry.URL),
+						slog.Any("error", err),
+					)
 				}
 			}
 
 			if userIntegrations.AppriseEnabled {
-				logger.Debug("[Integration] Sending entry %q for user #%d to Apprise", entry.URL, userIntegrations.UserID)
+				slog.Debug("Sending a new entry to Apprise",
+					slog.Int64("user_id", userIntegrations.UserID),
+					slog.Int64("entry_id", entry.ID),
+					slog.String("entry_url", entry.URL),
+				)
 
 				appriseServiceURLs := userIntegrations.AppriseURL
 				if feed.AppriseServiceURLs != "" {
@@ -231,7 +382,12 @@ func PushEntries(feed *model.Feed, entries model.Entries, userIntegrations *mode
 				)
 
 				if err := client.SendNotification(entry); err != nil {
-					logger.Error("[Integration] %v", err)
+					slog.Error("Unable to send entry to Apprise",
+						slog.Int64("user_id", userIntegrations.UserID),
+						slog.Int64("entry_id", entry.ID),
+						slog.String("entry_url", entry.URL),
+						slog.Any("error", err),
+					)
 				}
 			}
 		}

internal/logger/logger.go

@@ -1,97 +0,0 @@
-// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
-// SPDX-License-Identifier: Apache-2.0
-
-package logger // import "miniflux.app/v2/internal/logger"
-
-import (
-	"fmt"
-	"os"
-	"time"
-)
-
-var requestedLevel = InfoLevel
-var displayDateTime = false
-
-// LogLevel type.
-type LogLevel uint32
-
-const (
-	// FatalLevel should be used in fatal situations, the app will exit.
-	FatalLevel LogLevel = iota
-
-	// ErrorLevel should be used when someone should really look at the error.
-	ErrorLevel
-
-	// InfoLevel should be used during normal operations.
-	InfoLevel
-
-	// DebugLevel should be used only during development.
-	DebugLevel
-)
-
-func (level LogLevel) String() string {
-	switch level {
-	case DebugLevel:
-		return "DEBUG"
-	case InfoLevel:
-		return "INFO"
-	case ErrorLevel:
-		return "ERROR"
-	case FatalLevel:
-		return "FATAL"
-	default:
-		return "UNKNOWN"
-	}
-}
-
-// EnableDateTime enables date time in log messages.
-func EnableDateTime() {
-	displayDateTime = true
-}
-
-// EnableDebug increases logging, more verbose (debug)
-func EnableDebug() {
-	requestedLevel = DebugLevel
-	formatMessage(InfoLevel, "Debug mode enabled")
-}
-
-// Debug sends a debug log message.
-func Debug(format string, v ...interface{}) {
-	if requestedLevel >= DebugLevel {
-		formatMessage(DebugLevel, format, v...)
-	}
-}
-
-// Info sends an info log message.
-func Info(format string, v ...interface{}) {
-	if requestedLevel >= InfoLevel {
-		formatMessage(InfoLevel, format, v...)
-	}
-}
-
-// Error sends an error log message.
-func Error(format string, v ...interface{}) {
-	if requestedLevel >= ErrorLevel {
-		formatMessage(ErrorLevel, format, v...)
-	}
-}
-
-// Fatal sends a fatal log message and stop the execution of the program.
-func Fatal(format string, v ...interface{}) {
-	if requestedLevel >= FatalLevel {
-		formatMessage(FatalLevel, format, v...)
-		os.Exit(1)
-	}
-}
-
-func formatMessage(level LogLevel, format string, v ...interface{}) {
-	var prefix string
-
-	if displayDateTime {
-		prefix = fmt.Sprintf("[%s] [%s] ", time.Now().Format("2006-01-02T15:04:05"), level)
-	} else {
-		prefix = fmt.Sprintf("[%s] ", level)
-	}
-
-	fmt.Fprintf(os.Stderr, prefix+format+"\n", v...)
-}

internal/metric/metric.go

@@ -4,9 +4,9 @@
 package metric // import "miniflux.app/v2/internal/metric"
 
 import (
+	"log/slog"
 	"time"
 
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/storage"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -164,7 +164,7 @@ func NewCollector(store *storage.Storage, refreshInterval int) *Collector {
 // GatherStorageMetrics polls the database to fetch metrics.
 func (c *Collector) GatherStorageMetrics() {
 	for range time.Tick(time.Duration(c.refreshInterval) * time.Second) {
-		logger.Debug("[Metric] Collecting database metrics")
+		slog.Debug("Collecting metrics from the database")
 
 		usersGauge.Set(float64(c.store.CountUsers()))
 		brokenFeedsGauge.Set(float64(c.store.CountAllFeedsWithErrors()))

internal/oauth2/manager.go

@@ -6,8 +6,7 @@ package oauth2 // import "miniflux.app/v2/internal/oauth2"
 import (
 	"context"
 	"errors"
-
-	"miniflux.app/v2/internal/logger"
+	"log/slog"
 )
 
 type Manager struct {
@@ -32,7 +31,9 @@ func NewManager(ctx context.Context, clientID, clientSecret, redirectURL, oidcDi
 
 	if oidcDiscoveryEndpoint != "" {
 		if genericOidcProvider, err := NewOidcProvider(ctx, clientID, clientSecret, redirectURL, oidcDiscoveryEndpoint); err != nil {
-			logger.Error("[OAuth2] failed to initialize OIDC provider: %v", err)
+			slog.Error("Failed to initialize OIDC provider",
+				slog.Any("error", err),
+			)
 		} else {
 			m.AddProvider("oidc", genericOidcProvider)
 		}

internal/reader/atom/atom_03.go

@@ -6,11 +6,11 @@ package atom // import "miniflux.app/v2/internal/reader/atom"
 import (
 	"encoding/base64"
 	"html"
+	"log/slog"
 	"strings"
 	"time"
 
 	"miniflux.app/v2/internal/crypto"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/reader/date"
 	"miniflux.app/v2/internal/reader/sanitizer"
@@ -126,7 +126,11 @@ func (a *atom03Entry) entryDate() time.Time {
 	if dateText != "" {
 		result, err := date.Parse(dateText)
 		if err != nil {
-			logger.Error("atom: %v", err)
+			slog.Warn("Unable to parse date from Atom 0.3 feed",
+				slog.String("date", dateText),
+				slog.String("id", a.ID),
+				slog.Any("error", err),
+			)
 			return time.Now()
 		}
 

internal/reader/atom/atom_10.go

@@ -6,12 +6,12 @@ package atom // import "miniflux.app/v2/internal/reader/atom"
 import (
 	"encoding/xml"
 	"html"
+	"log/slog"
 	"strconv"
 	"strings"
 	"time"
 
 	"miniflux.app/v2/internal/crypto"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/reader/date"
 	"miniflux.app/v2/internal/reader/media"
@@ -144,7 +144,11 @@ func (a *atom10Entry) entryDate() time.Time {
 	if dateText != "" {
 		result, err := date.Parse(dateText)
 		if err != nil {
-			logger.Error("atom: %v (entry ID = %s)", err, a.ID)
+			slog.Warn("Unable to parse date from Atom 0.3 feed",
+				slog.String("date", dateText),
+				slog.String("id", a.ID),
+				slog.Any("error", err),
+			)
 			return time.Now()
 		}
 

internal/reader/handler/handler.go

@@ -4,22 +4,19 @@
 package handler // import "miniflux.app/v2/internal/reader/handler"
 
 import (
-	"fmt"
-	"time"
+	"log/slog"
 
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/errors"
 	"miniflux.app/v2/internal/http/client"
 	"miniflux.app/v2/internal/integration"
 	"miniflux.app/v2/internal/locale"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/reader/browser"
 	"miniflux.app/v2/internal/reader/icon"
 	"miniflux.app/v2/internal/reader/parser"
 	"miniflux.app/v2/internal/reader/processor"
 	"miniflux.app/v2/internal/storage"
-	"miniflux.app/v2/internal/timer"
 )
 
 var (
@@ -30,7 +27,10 @@ var (
 
 // CreateFeed fetch, parse and store a new feed.
 func CreateFeed(store *storage.Storage, userID int64, feedCreationRequest *model.FeedCreationRequest) (*model.Feed, error) {
-	defer timer.ExecutionTime(time.Now(), fmt.Sprintf("[CreateFeed] FeedURL=%s", feedCreationRequest.FeedURL))
+	slog.Debug("Begin feed creation process",
+		slog.Int64("user_id", userID),
+		slog.String("feed_url", feedCreationRequest.FeedURL),
+	)
 
 	user, storeErr := store.UserByID(userID)
 	if storeErr != nil {
@@ -90,7 +90,11 @@ func CreateFeed(store *storage.Storage, userID int64, feedCreationRequest *model
 		return nil, storeErr
 	}
 
-	logger.Debug("[CreateFeed] Feed saved with ID: %d", subscription.ID)
+	slog.Debug("Created feed",
+		slog.Int64("user_id", userID),
+		slog.Int64("feed_id", subscription.ID),
+		slog.String("feed_url", subscription.FeedURL),
+	)
 
 	checkFeedIcon(
 		store,
@@ -106,7 +110,12 @@ func CreateFeed(store *storage.Storage, userID int64, feedCreationRequest *model
 
 // RefreshFeed refreshes a feed.
 func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool) error {
-	defer timer.ExecutionTime(time.Now(), fmt.Sprintf("[RefreshFeed] feedID=%d", feedID))
+	slog.Debug("Begin feed refresh process",
+		slog.Int64("user_id", userID),
+		slog.Int64("feed_id", feedID),
+		slog.Bool("force_refresh", forceRefresh),
+	)
+
 	user, storeErr := store.UserByID(userID)
 	if storeErr != nil {
 		return storeErr
@@ -164,7 +173,10 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 	}
 
 	if originalFeed.IgnoreHTTPCache || response.IsModified(originalFeed.EtagHeader, originalFeed.LastModifiedHeader) {
-		logger.Debug("[RefreshFeed] Feed #%d has been modified", feedID)
+		slog.Debug("Feed modified",
+			slog.Int64("user_id", userID),
+			slog.Int64("feed_id", feedID),
+		)
 
 		updatedFeed, parseErr := parser.ParseFeed(response.EffectiveURL, response.BodyAsString())
 		if parseErr != nil {
@@ -187,7 +199,11 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 
 		userIntegrations, intErr := store.Integration(userID)
 		if intErr != nil {
-			logger.Error("[RefreshFeed] Fetching integrations for user %d failed: %v; the refresh process will go on, but no integrations will run this time.", userID, intErr)
+			slog.Error("Fetching integrations failed; the refresh process will go on, but no integrations will run this time",
+				slog.Int64("user_id", userID),
+				slog.Int64("feed_id", feedID),
+				slog.Any("error", intErr),
+			)
 		} else if userIntegrations != nil && len(newEntries) > 0 {
 			go integration.PushEntries(originalFeed, newEntries, userIntegrations)
 		}
@@ -206,7 +222,10 @@ func RefreshFeed(store *storage.Storage, userID, feedID int64, forceRefresh bool
 			originalFeed.AllowSelfSignedCertificates,
 		)
 	} else {
-		logger.Debug("[RefreshFeed] Feed #%d not modified", feedID)
+		slog.Debug("Feed not modified",
+			slog.Int64("user_id", userID),
+			slog.Int64("feed_id", feedID),
+		)
 	}
 
 	originalFeed.ResetErrorCounter()
@@ -224,12 +243,26 @@ func checkFeedIcon(store *storage.Storage, feedID int64, websiteURL, feedIconURL
 	if !store.HasIcon(feedID) {
 		icon, err := icon.FindIcon(websiteURL, feedIconURL, userAgent, fetchViaProxy, allowSelfSignedCertificates)
 		if err != nil {
-			logger.Debug(`[CheckFeedIcon] %v (feedID=%d websiteURL=%s)`, err, feedID, websiteURL)
+			slog.Warn("Unable to find feed icon",
+				slog.Int64("feed_id", feedID),
+				slog.String("website_url", websiteURL),
+				slog.String("feed_icon_url", feedIconURL),
+				slog.Any("error", err),
+			)
 		} else if icon == nil {
-			logger.Debug(`[CheckFeedIcon] No icon found (feedID=%d websiteURL=%s)`, feedID, websiteURL)
+			slog.Debug("No icon found",
+				slog.Int64("feed_id", feedID),
+				slog.String("website_url", websiteURL),
+				slog.String("feed_icon_url", feedIconURL),
+			)
 		} else {
 			if err := store.CreateFeedIcon(feedID, icon); err != nil {
-				logger.Debug(`[CheckFeedIcon] %v (feedID=%d websiteURL=%s)`, err, feedID, websiteURL)
+				slog.Error("Unable to store feed icon",
+					slog.Int64("feed_id", feedID),
+					slog.String("website_url", websiteURL),
+					slog.String("feed_icon_url", feedIconURL),
+					slog.Any("error", err),
+				)
 			}
 		}
 	}

internal/reader/icon/finder.go

@@ -13,7 +13,6 @@ import (
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/crypto"
 	"miniflux.app/v2/internal/http/client"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/urllib"
 
@@ -65,7 +64,6 @@ func generateIconURL(websiteURL, feedIconURL string) (iconURL string, err error)
 
 func fetchHTMLDocumentAndFindIconURL(websiteURL, userAgent string, fetchViaProxy, allowSelfSignedCertificates bool) (string, error) {
 	rootURL := urllib.RootURL(websiteURL)
-	logger.Debug("[FindIcon] Find icon from HTML webpage: %s", rootURL)
 
 	clt := client.NewClientWithConfig(rootURL, config.Opts)
 	clt.WithUserAgent(userAgent)

internal/reader/json/json.go

@@ -4,11 +4,11 @@
 package json // import "miniflux.app/v2/internal/reader/json"
 
 import (
+	"log/slog"
 	"strings"
 	"time"
 
 	"miniflux.app/v2/internal/crypto"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/reader/date"
 	"miniflux.app/v2/internal/reader/sanitizer"
@@ -110,7 +110,11 @@ func (j *jsonItem) GetDate() time.Time {
 		if value != "" {
 			d, err := date.Parse(value)
 			if err != nil {
-				logger.Error("json: %v", err)
+				slog.Warn("Unable to parse date from JSON feed",
+					slog.String("date", value),
+					slog.String("url", j.URL),
+					slog.Any("error", err),
+				)
 				return time.Now()
 			}
 

internal/reader/opml/handler.go

@@ -4,11 +4,9 @@
 package opml // import "miniflux.app/v2/internal/reader/opml"
 
 import (
-	"errors"
 	"fmt"
 	"io"
 
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/storage"
 )
@@ -53,21 +51,18 @@ func (h *Handler) Import(userID int64, data io.Reader) error {
 			if subscription.CategoryName == "" {
 				category, err = h.store.FirstCategory(userID)
 				if err != nil {
-					logger.Error("[OPML:Import] %v", err)
-					return errors.New("unable to find first category")
+					return fmt.Errorf("opml: unable to find first category: %w", err)
 				}
 			} else {
 				category, err = h.store.CategoryByTitle(userID, subscription.CategoryName)
 				if err != nil {
-					logger.Error("[OPML:Import] %v", err)
-					return errors.New("unable to search category by title")
+					return fmt.Errorf("opml: unable to search category by title: %w", err)
 				}
 
 				if category == nil {
 					category, err = h.store.CreateCategory(userID, &model.CategoryRequest{Title: subscription.CategoryName})
 					if err != nil {
-						logger.Error("[OPML:Import] %v", err)
-						return fmt.Errorf(`unable to create this category: %q`, subscription.CategoryName)
+						return fmt.Errorf(`opml: unable to create this category: %q`, subscription.CategoryName)
 					}
 				}
 			}

internal/reader/opml/serializer.go

@@ -7,10 +7,9 @@ import (
 	"bufio"
 	"bytes"
 	"encoding/xml"
+	"log/slog"
 	"sort"
 	"time"
-
-	"miniflux.app/v2/internal/logger"
 )
 
 // Serialize returns a SubcriptionList in OPML format.
@@ -23,7 +22,9 @@ func Serialize(subscriptions SubcriptionList) string {
 	encoder := xml.NewEncoder(writer)
 	encoder.Indent("", "    ")
 	if err := encoder.Encode(opmlDocument); err != nil {
-		logger.Error("[OPML:Serialize] %v", err)
+		slog.Error("Unable to serialize OPML document",
+			slog.Any("error", err),
+		)
 		return ""
 	}
 

internal/reader/processor/processor.go

@@ -6,6 +6,7 @@ package processor
 import (
 	"errors"
 	"fmt"
+	"log/slog"
 	"math"
 	"regexp"
 	"strconv"
@@ -15,7 +16,6 @@ import (
 
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/http/client"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/metric"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/reader/browser"
@@ -43,7 +43,13 @@ func ProcessFeedEntries(store *storage.Storage, feed *model.Feed, user *model.Us
 	for i := len(feed.Entries) - 1; i >= 0; i-- {
 		entry := feed.Entries[i]
 
-		logger.Debug("[Processor] Processing entry %q from feed %q", entry.URL, feed.FeedURL)
+		slog.Debug("Processing entry",
+			slog.Int64("user_id", user.ID),
+			slog.Int64("entry_id", entry.ID),
+			slog.String("entry_url", entry.URL),
+			slog.Int64("feed_id", feed.ID),
+			slog.String("feed_url", feed.FeedURL),
+		)
 
 		if isBlockedEntry(feed, entry) || !isAllowedEntry(feed, entry) {
 			continue
@@ -52,7 +58,13 @@ func ProcessFeedEntries(store *storage.Storage, feed *model.Feed, user *model.Us
 		url := getUrlFromEntry(feed, entry)
 		entryIsNew := !store.EntryURLExists(feed.ID, entry.URL)
 		if feed.Crawler && (entryIsNew || forceRefresh) {
-			logger.Debug("[Processor] Crawling entry %q from feed %q", url, feed.FeedURL)
+			slog.Debug("Scraping entry",
+				slog.Int64("user_id", user.ID),
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Int64("feed_id", feed.ID),
+				slog.String("feed_url", feed.FeedURL),
+			)
 
 			startTime := time.Now()
 			content, scraperErr := scraper.Fetch(
@@ -73,7 +85,14 @@ func ProcessFeedEntries(store *storage.Storage, feed *model.Feed, user *model.Us
 			}
 
 			if scraperErr != nil {
-				logger.Error(`[Processor] Unable to crawl this entry: %q => %v`, entry.URL, scraperErr)
+				slog.Warn("Unable to scrape entry",
+					slog.Int64("user_id", user.ID),
+					slog.Int64("entry_id", entry.ID),
+					slog.String("entry_url", entry.URL),
+					slog.Int64("feed_id", feed.ID),
+					slog.String("feed_url", feed.FeedURL),
+					slog.Any("error", scraperErr),
+				)
 			} else if content != "" {
 				// We replace the entry content only if the scraper doesn't return any error.
 				entry.Content = content
@@ -96,7 +115,13 @@ func isBlockedEntry(feed *model.Feed, entry *model.Entry) bool {
 	if feed.BlocklistRules != "" {
 		match, _ := regexp.MatchString(feed.BlocklistRules, entry.Title)
 		if match {
-			logger.Debug("[Processor] Blocking entry %q from feed %q based on rule %q", entry.Title, feed.FeedURL, feed.BlocklistRules)
+			slog.Debug("Blocking entry based on rule",
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Int64("feed_id", feed.ID),
+				slog.String("feed_url", feed.FeedURL),
+				slog.String("rule", feed.BlocklistRules),
+			)
 			return true
 		}
 	}
@@ -107,7 +132,13 @@ func isAllowedEntry(feed *model.Feed, entry *model.Entry) bool {
 	if feed.KeeplistRules != "" {
 		match, _ := regexp.MatchString(feed.KeeplistRules, entry.Title)
 		if match {
-			logger.Debug("[Processor] Allow entry %q from feed %q based on rule %q", entry.Title, feed.FeedURL, feed.KeeplistRules)
+			slog.Debug("Allow entry based on rule",
+				slog.Int64("entry_id", entry.ID),
+				slog.String("entry_url", entry.URL),
+				slog.Int64("feed_id", feed.ID),
+				slog.String("feed_url", feed.FeedURL),
+				slog.String("rule", feed.KeeplistRules),
+			)
 			return true
 		}
 		return false
@@ -160,9 +191,22 @@ func getUrlFromEntry(feed *model.Feed, entry *model.Entry) string {
 		if len(parts) >= 3 {
 			re := regexp.MustCompile(parts[1])
 			url = re.ReplaceAllString(entry.URL, parts[2])
-			logger.Debug(`[Processor] Rewriting entry URL %s to %s`, entry.URL, url)
+			slog.Debug("Rewriting entry URL",
+				slog.Int64("entry_id", entry.ID),
+				slog.String("original_entry_url", entry.URL),
+				slog.String("rewritten_entry_url", url),
+				slog.Int64("feed_id", feed.ID),
+				slog.String("feed_url", feed.FeedURL),
+			)
 		} else {
-			logger.Debug("[Processor] Cannot find search and replace terms for replace rule %s", feed.UrlRewriteRules)
+			slog.Debug("Cannot find search and replace terms for replace rule",
+				slog.Int64("entry_id", entry.ID),
+				slog.String("original_entry_url", entry.URL),
+				slog.String("rewritten_entry_url", url),
+				slog.Int64("feed_id", feed.ID),
+				slog.String("feed_url", feed.FeedURL),
+				slog.String("url_rewrite_rules", feed.UrlRewriteRules),
+			)
 		}
 	}
 	return url
@@ -173,7 +217,14 @@ func updateEntryReadingTime(store *storage.Storage, feed *model.Feed, entry *mod
 		if entryIsNew {
 			watchTime, err := fetchYouTubeWatchTime(entry.URL)
 			if err != nil {
-				logger.Error("[Processor] Unable to fetch YouTube watch time: %q => %v", entry.URL, err)
+				slog.Warn("Unable to fetch YouTube watch time",
+					slog.Int64("user_id", user.ID),
+					slog.Int64("entry_id", entry.ID),
+					slog.String("entry_url", entry.URL),
+					slog.Int64("feed_id", feed.ID),
+					slog.String("feed_url", feed.FeedURL),
+					slog.Any("error", err),
+				)
 			}
 			entry.ReadingTime = watchTime
 		} else {
@@ -185,7 +236,14 @@ func updateEntryReadingTime(store *storage.Storage, feed *model.Feed, entry *mod
 		if entryIsNew {
 			watchTime, err := fetchOdyseeWatchTime(entry.URL)
 			if err != nil {
-				logger.Error("[Processor] Unable to fetch Odysee watch time: %q => %v", entry.URL, err)
+				slog.Warn("Unable to fetch Odysee watch time",
+					slog.Int64("user_id", user.ID),
+					slog.Int64("entry_id", entry.ID),
+					slog.String("entry_url", entry.URL),
+					slog.Int64("feed_id", feed.ID),
+					slog.String("feed_url", feed.FeedURL),
+					slog.Any("error", err),
+				)
 			}
 			entry.ReadingTime = watchTime
 		} else {

internal/reader/rdf/rdf.go

@@ -6,11 +6,11 @@ package rdf // import "miniflux.app/v2/internal/reader/rdf"
 import (
 	"encoding/xml"
 	"html"
+	"log/slog"
 	"strings"
 	"time"
 
 	"miniflux.app/v2/internal/crypto"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/reader/date"
 	"miniflux.app/v2/internal/reader/dublincore"
@@ -100,7 +100,11 @@ func (r *rdfItem) entryDate() time.Time {
 	if r.DublinCoreDate != "" {
 		result, err := date.Parse(r.DublinCoreDate)
 		if err != nil {
-			logger.Error("rdf: %v (entry link = %s)", err, r.Link)
+			slog.Warn("Unable to parse date from RDF feed",
+				slog.String("date", r.DublinCoreDate),
+				slog.String("link", r.Link),
+				slog.Any("error", err),
+			)
 			return time.Now()
 		}
 

internal/reader/readability/readability.go

@@ -7,12 +7,11 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"log/slog"
 	"math"
 	"regexp"
 	"strings"
 
-	"miniflux.app/v2/internal/logger"
-
 	"github.com/PuerkitoBio/goquery"
 	"golang.org/x/net/html"
 )
@@ -83,10 +82,12 @@ func ExtractContent(page io.Reader) (string, error) {
 	removeUnlikelyCandidates(document)
 
 	candidates := getCandidates(document)
-	logger.Debug("[Readability] Candidates: %v", candidates)
-
 	topCandidate := getTopCandidate(document, candidates)
-	logger.Debug("[Readability] TopCandidate: %v", topCandidate)
+
+	slog.Debug("Readability parsing",
+		slog.Any("candidates", candidates),
+		slog.Any("topCandidate", topCandidate),
+	)
 
 	output := getArticle(topCandidate, candidates)
 	return output, nil

internal/reader/rewrite/rewrite_functions.go

@@ -7,12 +7,12 @@ import (
 	"encoding/base64"
 	"fmt"
 	"html"
+	"log/slog"
 	"net/url"
 	"regexp"
 	"strings"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 
 	"github.com/PuerkitoBio/goquery"
 	"github.com/yuin/goldmark"
@@ -359,7 +359,9 @@ func addHackerNewsLinksUsing(entryContent, app string) string {
 				open_with_hack := `<a href="` + url + `">Open with HACK</a>`
 				a.Parent().AppendHtml(" " + open_with_hack)
 			} else {
-				logger.Error("[openHackerNewsLinksWith] unknown app provided: %q", app)
+				slog.Warn("Unknown app provided for openHackerNewsLinksWith rewrite rule",
+					slog.String("app", app),
+				)
 				return
 			}
 		})

internal/reader/rewrite/rewriter.go

@@ -4,11 +4,11 @@
 package rewrite // import "miniflux.app/v2/internal/reader/rewrite"
 
 import (
+	"log/slog"
 	"strconv"
 	"strings"
 	"text/scanner"
 
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/urllib"
 )
@@ -28,7 +28,10 @@ func Rewriter(entryURL string, entry *model.Entry, customRewriteRules string) {
 	rules := parseRules(rulesList)
 	rules = append(rules, rule{name: "add_pdf_download_link"})
 
-	logger.Debug(`[Rewrite] Applying rules %v for %q`, rules, entryURL)
+	slog.Debug("Rewrite rules applied",
+		slog.Any("rules", rules),
+		slog.String("entry_url", entryURL),
+	)
 
 	for _, rule := range rules {
 		applyRule(entryURL, entry, rule)
@@ -89,21 +92,30 @@ func applyRule(entryURL string, entry *model.Entry, rule rule) {
 		if len(rule.args) >= 2 {
 			entry.Content = replaceCustom(entry.Content, rule.args[0], rule.args[1])
 		} else {
-			logger.Debug("[Rewrite] Cannot find search and replace terms for replace rule %s", rule)
+			slog.Warn("Cannot find search and replace terms for replace rule",
+				slog.Any("rule", rule),
+				slog.String("entry_url", entryURL),
+			)
 		}
 	case "replace_title":
 		// Format: replace_title("search-term"|"replace-term")
 		if len(rule.args) >= 2 {
 			entry.Title = replaceCustom(entry.Title, rule.args[0], rule.args[1])
 		} else {
-			logger.Debug("[Rewrite] Cannot find search and replace terms for replace rule %s", rule)
+			slog.Warn("Cannot find search and replace terms for replace_title rule",
+				slog.Any("rule", rule),
+				slog.String("entry_url", entryURL),
+			)
 		}
 	case "remove":
 		// Format: remove("#selector > .element, .another")
 		if len(rule.args) >= 1 {
 			entry.Content = removeCustom(entry.Content, rule.args[0])
 		} else {
-			logger.Debug("[Rewrite] Cannot find selector for remove rule %s", rule)
+			slog.Warn("Cannot find selector for remove rule",
+				slog.Any("rule", rule),
+				slog.String("entry_url", entryURL),
+			)
 		}
 	case "add_castopod_episode":
 		entry.Content = addCastopodEpisode(entryURL, entry.Content)

internal/reader/rss/rss.go

@@ -6,13 +6,13 @@ package rss // import "miniflux.app/v2/internal/reader/rss"
 import (
 	"encoding/xml"
 	"html"
+	"log/slog"
 	"path"
 	"strconv"
 	"strings"
 	"time"
 
 	"miniflux.app/v2/internal/crypto"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/reader/date"
 	"miniflux.app/v2/internal/reader/dublincore"
@@ -216,7 +216,11 @@ func (r *rssItem) entryDate() time.Time {
 	if value != "" {
 		result, err := date.Parse(value)
 		if err != nil {
-			logger.Error("rss: %v (entry GUID = %s)", err, r.GUID)
+			slog.Warn("Unable to parse date from RSS feed",
+				slog.String("date", value),
+				slog.String("guid", r.GUID.Data),
+				slog.Any("error", err),
+			)
 			return time.Now()
 		}
 

internal/reader/scraper/scraper.go

@@ -7,11 +7,11 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log/slog"
 	"strings"
 
 	"miniflux.app/v2/internal/config"
 	"miniflux.app/v2/internal/http/client"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/reader/readability"
 	"miniflux.app/v2/internal/urllib"
 
@@ -55,10 +55,15 @@ func Fetch(websiteURL, rules, userAgent string, cookie string, allowSelfSignedCe
 
 	var content string
 	if sameSite && rules != "" {
-		logger.Debug(`[Scraper] Using rules %q for %q`, rules, websiteURL)
+		slog.Debug("Extracting content with custom rules",
+			"url", websiteURL,
+			"rules", rules,
+		)
 		content, err = scrapContent(response.Body, rules)
 	} else {
-		logger.Debug(`[Scraper] Using readability for %q`, websiteURL)
+		slog.Debug("Extracting content with readability",
+			"url", websiteURL,
+		)
 		content, err = readability.ExtractContent(response.Body)
 	}
 

internal/storage/category.go

@@ -238,7 +238,7 @@ func (s *Storage) RemoveCategory(userID, categoryID int64) error {
 func (s *Storage) RemoveAndReplaceCategoriesByName(userid int64, titles []string) error {
 	tx, err := s.db.Begin()
 	if err != nil {
-		return errors.New("unable to begin transaction")
+		return errors.New("store: unable to begin transaction")
 	}
 
 	titleParam := pq.Array(titles)
@@ -247,11 +247,11 @@ func (s *Storage) RemoveAndReplaceCategoriesByName(userid int64, titles []string
 	err = tx.QueryRow(query, userid, titleParam).Scan(&count)
 	if err != nil {
 		tx.Rollback()
-		return errors.New("unable to retrieve category count")
+		return errors.New("store: unable to retrieve category count")
 	}
 	if count < 1 {
 		tx.Rollback()
-		return errors.New("at least 1 category must remain after deletion")
+		return errors.New("store: at least 1 category must remain after deletion")
 	}
 
 	query = `
@@ -268,14 +268,14 @@ func (s *Storage) RemoveAndReplaceCategoriesByName(userid int64, titles []string
 	_, err = tx.Exec(query, userid, titleParam)
 	if err != nil {
 		tx.Rollback()
-		return fmt.Errorf("unable to replace categories: %v", err)
+		return fmt.Errorf("store: unable to replace categories: %v", err)
 	}
 
 	query = "DELETE FROM categories WHERE user_id = $1 AND title = ANY($2)"
 	_, err = tx.Exec(query, userid, titleParam)
 	if err != nil {
 		tx.Rollback()
-		return fmt.Errorf("unable to delete categories: %v", err)
+		return fmt.Errorf("store: unable to delete categories: %v", err)
 	}
 	tx.Commit()
 	return nil

internal/storage/entry.go

@@ -7,10 +7,10 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"log/slog"
 	"time"
 
 	"miniflux.app/v2/internal/crypto"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 
 	"github.com/lib/pq"
@@ -52,7 +52,10 @@ func (s *Storage) CountUnreadEntries(userID int64) int {
 
 	n, err := builder.CountEntries()
 	if err != nil {
-		logger.Error(`store: unable to count unread entries for user #%d: %v`, userID, err)
+		slog.Error("Unable to count unread entries",
+			slog.Int64("user_id", userID),
+			slog.Any("error", err),
+		)
 		return 0
 	}
 
@@ -316,7 +319,11 @@ func (s *Storage) RefreshFeedEntries(userID, feedID int64, entries model.Entries
 
 	go func() {
 		if err := s.cleanupEntries(feedID, entryHashes); err != nil {
-			logger.Error(`store: feed #%d: %v`, feedID, err)
+			slog.Error("Unable to cleanup entries",
+				slog.Int64("user_id", userID),
+				slog.Int64("feed_id", feedID),
+				slog.Any("error", err),
+			)
 		}
 	}()
 
@@ -463,7 +470,10 @@ func (s *Storage) MarkAllAsRead(userID int64) error {
 	}
 
 	count, _ := result.RowsAffected()
-	logger.Debug("[Storage:MarkAllAsRead] %d items marked as read", count)
+	slog.Debug("Marked all entries as read",
+		slog.Int64("user_id", userID),
+		slog.Int64("nb_entries", count),
+	)
 
 	return nil
 }
@@ -490,7 +500,10 @@ func (s *Storage) MarkGloballyVisibleFeedsAsRead(userID int64) error {
 	}
 
 	count, _ := result.RowsAffected()
-	logger.Debug("[Storage:MarkGloballyVisibleFeedsAsRead] %d items marked as read", count)
+	slog.Debug("Marked globally visible feed entries as read",
+		slog.Int64("user_id", userID),
+		slog.Int64("nb_entries", count),
+	)
 
 	return nil
 }
@@ -512,7 +525,11 @@ func (s *Storage) MarkFeedAsRead(userID, feedID int64, before time.Time) error {
 	}
 
 	count, _ := result.RowsAffected()
-	logger.Debug("[Storage:MarkFeedAsRead] %d items marked as read", count)
+	slog.Debug("Marked feed entries as read",
+		slog.Int64("user_id", userID),
+		slog.Int64("feed_id", feedID),
+		slog.Int64("nb_entries", count),
+	)
 
 	return nil
 }
@@ -540,7 +557,11 @@ func (s *Storage) MarkCategoryAsRead(userID, categoryID int64, before time.Time)
 	}
 
 	count, _ := result.RowsAffected()
-	logger.Debug("[Storage:MarkCategoryAsRead] %d items marked as read", count)
+	slog.Debug("Marked category entries as read",
+		slog.Int64("user_id", userID),
+		slog.Int64("category_id", categoryID),
+		slog.Int64("nb_entries", count),
+	)
 
 	return nil
 }

internal/storage/entry_pagination_builder.go

@@ -7,10 +7,8 @@ import (
 	"database/sql"
 	"fmt"
 	"strings"
-	"time"
 
 	"miniflux.app/v2/internal/model"
-	"miniflux.app/v2/internal/timer"
 )
 
 // EntryPaginationBuilder is a builder for entry prev/next queries.
@@ -101,8 +99,6 @@ func (e *EntryPaginationBuilder) Entries() (*model.Entry, *model.Entry, error) {
 }
 
 func (e *EntryPaginationBuilder) getPrevNextID(tx *sql.Tx) (prevID int64, nextID int64, err error) {
-	defer timer.ExecutionTime(time.Now(), fmt.Sprintf("[EntryPaginationBuilder] %v, %v", e.conditions, e.args))
-
 	cte := `
 		WITH entry_pagination AS (
 			SELECT

internal/storage/feed.go

@@ -7,11 +7,10 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
-	"runtime"
+	"log/slog"
 	"sort"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 )
 
@@ -432,7 +431,11 @@ func (s *Storage) RemoveFeed(userID, feedID int64) error {
 			return fmt.Errorf(`store: unable to read user feed entry ID: %v`, err)
 		}
 
-		logger.Debug(`[FEED DELETION] Deleting entry #%d of feed #%d for user #%d (%d GoRoutines)`, entryID, feedID, userID, runtime.NumGoroutine())
+		slog.Debug("Deleting entry",
+			slog.Int64("user_id", userID),
+			slog.Int64("feed_id", feedID),
+			slog.Int64("entry_id", entryID),
+		)
 
 		if _, err := s.db.Exec(`DELETE FROM entries WHERE id=$1 AND user_id=$2`, entryID, userID); err != nil {
 			return fmt.Errorf(`store: unable to delete user feed entries #%d: %v`, entryID, err)

internal/storage/user.go

@@ -6,11 +6,11 @@ package storage // import "miniflux.app/v2/internal/storage"
 import (
 	"database/sql"
 	"fmt"
+	"log/slog"
 	"runtime"
 	"strings"
 
 	"miniflux.app/v2/internal/crypto"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 
 	"github.com/lib/pq"
@@ -506,14 +506,20 @@ func (s *Storage) RemoveUser(userID int64) error {
 func (s *Storage) RemoveUserAsync(userID int64) {
 	go func() {
 		if err := s.deleteUserFeeds(userID); err != nil {
-			logger.Error(`%v`, err)
+			slog.Error("Unable to delete user feedd",
+				slog.Int64("user_id", userID),
+				slog.Any("error", err),
+			)
 			return
 		}
 
 		s.db.Exec(`DELETE FROM users WHERE id=$1`, userID)
 		s.db.Exec(`DELETE FROM integrations WHERE user_id=$1`, userID)
 
-		logger.Debug(`[MASS DELETE] User #%d has been deleted (%d GoRoutines)`, userID, runtime.NumGoroutine())
+		slog.Debug("User deleted",
+			slog.Int64("user_id", userID),
+			slog.Int("goroutines", runtime.NumGoroutine()),
+		)
 	}()
 }
 
@@ -528,7 +534,11 @@ func (s *Storage) deleteUserFeeds(userID int64) error {
 		var feedID int64
 		rows.Scan(&feedID)
 
-		logger.Debug(`[USER DELETION] Deleting feed #%d for user #%d (%d GoRoutines)`, feedID, userID, runtime.NumGoroutine())
+		slog.Debug("Deleting feed",
+			slog.Int64("user_id", userID),
+			slog.Int64("feed_id", feedID),
+			slog.Int("goroutines", runtime.NumGoroutine()),
+		)
 
 		if err := s.RemoveFeed(userID, feedID); err != nil {
 			return err

internal/template/engine.go

@@ -7,12 +7,12 @@ import (
 	"bytes"
 	"embed"
 	"html/template"
+	"log/slog"
 	"strings"
 	"time"
 
 	"miniflux.app/v2/internal/errors"
 	"miniflux.app/v2/internal/locale"
-	"miniflux.app/v2/internal/logger"
 
 	"github.com/gorilla/mux"
 )
@@ -73,7 +73,10 @@ func (e *Engine) ParseTemplates() error {
 		templateContents.WriteString(commonTemplateContents.String())
 		templateContents.Write(fileData)
 
-		logger.Debug("[Template] Parsing: %s", templateName)
+		slog.Debug("Parsing template",
+			slog.String("template_name", templateName),
+		)
+
 		e.templates[templateName] = template.Must(template.New("main").Funcs(e.funcMap.Map()).Parse(templateContents.String()))
 	}
 
@@ -89,7 +92,9 @@ func (e *Engine) ParseTemplates() error {
 			return err
 		}
 
-		logger.Debug("[Template] Parsing: %s", templateName)
+		slog.Debug("Parsing template",
+			slog.String("template_name", templateName),
+		)
 		e.templates[templateName] = template.Must(template.New("base").Funcs(e.funcMap.Map()).Parse(string(fileData)))
 	}
 
@@ -100,7 +105,7 @@ func (e *Engine) ParseTemplates() error {
 func (e *Engine) Render(name string, data map[string]interface{}) []byte {
 	tpl, ok := e.templates[name]
 	if !ok {
-		logger.Fatal("[Template] The template %s does not exists", name)
+		panic("This template does not exists: " + name)
 	}
 
 	printer := locale.NewPrinter(data["language"].(string))
@@ -132,7 +137,7 @@ func (e *Engine) Render(name string, data map[string]interface{}) []byte {
 	var b bytes.Buffer
 	err := tpl.ExecuteTemplate(&b, "base", data)
 	if err != nil {
-		logger.Fatal("[Template] Unable to render template: %v", err)
+		panic(err)
 	}
 
 	return b.Bytes()

internal/timer/timer.go

@@ -1,16 +0,0 @@
-// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
-// SPDX-License-Identifier: Apache-2.0
-
-package timer // import "miniflux.app/v2/internal/timer"
-
-import (
-	"time"
-
-	"miniflux.app/v2/internal/logger"
-)
-
-// ExecutionTime returns the elapsed time of a block of code.
-func ExecutionTime(start time.Time, name string) {
-	elapsed := time.Since(start)
-	logger.Debug("%s took %s", name, elapsed)
-}

internal/ui/api_key_remove.go

@@ -9,14 +9,14 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 )
 
 func (h *handler) removeAPIKey(w http.ResponseWriter, r *http.Request) {
 	keyID := request.RouteInt64Param(r, "keyID")
 	err := h.store.RemoveAPIKey(request.UserID(r), keyID)
 	if err != nil {
-		logger.Error("[UI:RemoveAPIKey] %v", err)
+		html.ServerError(w, r, err)
+		return
 	}
 
 	html.Redirect(w, r, route.Path(h.router, "apiKeys"))

internal/ui/api_key_save.go

@@ -9,7 +9,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
@@ -47,9 +46,7 @@ func (h *handler) saveAPIKey(w http.ResponseWriter, r *http.Request) {
 
 	apiKey := model.NewAPIKey(user.ID, apiKeyForm.Description)
 	if err = h.store.CreateAPIKey(apiKey); err != nil {
-		logger.Error("[UI:SaveAPIKey] %v", err)
-		view.Set("errorMessage", "error.unable_to_create_api_key")
-		html.OK(w, r, view.Render("create_api_key"))
+		html.ServerError(w, r, err)
 		return
 	}
 

internal/ui/category_save.go

@@ -9,7 +9,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
@@ -43,9 +42,7 @@ func (h *handler) saveCategory(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if _, err = h.store.CreateCategory(loggedUser.ID, categoryRequest); err != nil {
-		logger.Error("[UI:SaveCategory] %v", err)
-		view.Set("errorMessage", "error.unable_to_create_category")
-		html.OK(w, r, view.Render("create_category"))
+		html.ServerError(w, r, err)
 		return
 	}
 

internal/ui/category_update.go

@@ -9,7 +9,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
@@ -60,9 +59,7 @@ func (h *handler) updateCategory(w http.ResponseWriter, r *http.Request) {
 
 	categoryRequest.Patch(category)
 	if err := h.store.UpdateCategory(category); err != nil {
-		logger.Error("[UI:UpdateCategory] %v", err)
-		view.Set("errorMessage", "error.unable_to_update_category")
-		html.OK(w, r, view.Render("edit_category"))
+		html.ServerError(w, r, err)
 		return
 	}
 

internal/ui/feed_refresh.go

@@ -4,12 +4,12 @@
 package ui // import "miniflux.app/v2/internal/ui"
 
 import (
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	feedHandler "miniflux.app/v2/internal/reader/handler"
 )
 
@@ -17,7 +17,12 @@ func (h *handler) refreshFeed(w http.ResponseWriter, r *http.Request) {
 	feedID := request.RouteInt64Param(r, "feedID")
 	forceRefresh := request.QueryBoolParam(r, "forceRefresh", false)
 	if err := feedHandler.RefreshFeed(h.store, request.UserID(r), feedID, forceRefresh); err != nil {
-		logger.Error("[UI:RefreshFeed] %v", err)
+		slog.Warn("Unable to refresh feed",
+			slog.Int64("user_id", request.UserID(r)),
+			slog.Int64("feed_id", feedID),
+			slog.Bool("force_refresh", forceRefresh),
+			slog.Any("error", err),
+		)
 	}
 
 	html.Redirect(w, r, route.Path(h.router, "feedEntries", "feedID", feedID))

internal/ui/feed_update.go

@@ -10,7 +10,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
@@ -74,9 +73,7 @@ func (h *handler) updateFeed(w http.ResponseWriter, r *http.Request) {
 
 	err = h.store.UpdateFeed(feedForm.Merge(feed))
 	if err != nil {
-		logger.Error("[UI:UpdateFeed] %v", err)
-		view.Set("errorMessage", "error.unable_to_update_feed")
-		html.OK(w, r, view.Render("edit_feed"))
+		html.ServerError(w, r, err)
 		return
 	}
 

internal/ui/integration_pocket.go

@@ -4,6 +4,7 @@
 package ui // import "miniflux.app/v2/internal/ui"
 
 import (
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/config"
@@ -12,7 +13,6 @@ import (
 	"miniflux.app/v2/internal/http/route"
 	"miniflux.app/v2/internal/integration/pocket"
 	"miniflux.app/v2/internal/locale"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/ui/session"
 )
 
@@ -35,7 +35,10 @@ func (h *handler) pocketAuthorize(w http.ResponseWriter, r *http.Request) {
 	redirectURL := config.Opts.RootURL() + route.Path(h.router, "pocketCallback")
 	requestToken, err := connector.RequestToken(redirectURL)
 	if err != nil {
-		logger.Error("[Pocket:Authorize] %v", err)
+		slog.Warn("Pocket authorization request failed",
+			slog.Any("user_id", user.ID),
+			slog.Any("error", err),
+		)
 		sess.NewFlashErrorMessage(printer.Printf("error.pocket_request_token"))
 		html.Redirect(w, r, route.Path(h.router, "integrations"))
 		return
@@ -64,7 +67,10 @@ func (h *handler) pocketCallback(w http.ResponseWriter, r *http.Request) {
 	connector := pocket.NewConnector(config.Opts.PocketConsumerKey(integration.PocketConsumerKey))
 	accessToken, err := connector.AccessToken(request.PocketRequestToken(r))
 	if err != nil {
-		logger.Error("[Pocket:Callback] %v", err)
+		slog.Warn("Unable to get Pocket access token",
+			slog.Any("user_id", user.ID),
+			slog.Any("error", err),
+		)
 		sess.NewFlashErrorMessage(printer.Printf("error.pocket_access_token"))
 		html.Redirect(w, r, route.Path(h.router, "integrations"))
 		return

internal/ui/login_check.go

@@ -4,6 +4,7 @@
 package ui // import "miniflux.app/v2/internal/ui"
 
 import (
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/config"
@@ -11,7 +12,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
 	"miniflux.app/v2/internal/ui/view"
@@ -27,13 +27,25 @@ func (h *handler) checkLogin(w http.ResponseWriter, r *http.Request) {
 	view.Set("form", authForm)
 
 	if err := authForm.Validate(); err != nil {
-		logger.Error("[UI:CheckLogin] %v", err)
+		slog.Warn("Validation error during login check",
+			slog.Bool("authentication_failed", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("username", authForm.Username),
+			slog.Any("error", err),
+		)
 		html.OK(w, r, view.Render("login"))
 		return
 	}
 
 	if err := h.store.CheckPassword(authForm.Username, authForm.Password); err != nil {
-		logger.Error("[UI:CheckLogin] [ClientIP=%s] %v", clientIP, err)
+		slog.Warn("Incorrect username or password",
+			slog.Bool("authentication_failed", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("username", authForm.Username),
+			slog.Any("error", err),
+		)
 		html.OK(w, r, view.Render("login"))
 		return
 	}
@@ -44,7 +56,14 @@ func (h *handler) checkLogin(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	logger.Info("[UI:CheckLogin] username=%s just logged in", authForm.Username)
+	slog.Info("User authenticated successfully with username/password",
+		slog.Bool("authentication_successful", true),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", userID),
+		slog.String("username", authForm.Username),
+	)
+
 	h.store.SetLastLogin(userID)
 
 	user, err := h.store.UserByID(userID)

internal/ui/logout.go

@@ -11,7 +11,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/ui/session"
 )
 
@@ -27,7 +26,8 @@ func (h *handler) logout(w http.ResponseWriter, r *http.Request) {
 	sess.SetTheme(user.Theme)
 
 	if err := h.store.RemoveUserSessionByToken(user.ID, request.UserSessionToken(r)); err != nil {
-		logger.Error("[UI:Logout] %v", err)
+		html.ServerError(w, r, err)
+		return
 	}
 
 	http.SetCookie(w, cookie.Expired(

internal/ui/middleware.go

@@ -6,6 +6,7 @@ package ui // import "miniflux.app/v2/internal/ui"
 import (
 	"context"
 	"errors"
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/config"
@@ -13,7 +14,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/ui/session"
@@ -38,11 +38,17 @@ func (m *middleware) handleUserSession(next http.Handler) http.Handler {
 			if m.isPublicRoute(r) {
 				next.ServeHTTP(w, r)
 			} else {
-				logger.Debug("[UI:UserSession] Session not found, redirect to login page")
+				slog.Debug("Redirecting to login page because no user session has been found",
+					slog.Any("url", r.RequestURI),
+				)
 				html.Redirect(w, r, route.Path(m.router, "login"))
 			}
 		} else {
-			logger.Debug("[UI:UserSession] %s", session)
+			slog.Debug("User session found",
+				slog.Any("url", r.RequestURI),
+				slog.Int64("user_id", session.UserID),
+				slog.Int64("user_session_id", session.ID),
+			)
 
 			ctx := r.Context()
 			ctx = context.WithValue(ctx, request.UserIDContextKey, session.UserID)
@@ -62,14 +68,16 @@ func (m *middleware) handleAppSession(next http.Handler) http.Handler {
 		if session == nil {
 			if request.IsAuthenticated(r) {
 				userID := request.UserID(r)
-				logger.Debug("[UI:AppSession] Cookie expired but user #%d is logged: creating a new session", userID)
+				slog.Debug("Cookie expired but user is logged: creating a new app session",
+					slog.Int64("user_id", userID),
+				)
 				session, err = m.store.CreateAppSessionWithUserPrefs(userID)
 				if err != nil {
 					html.ServerError(w, r, err)
 					return
 				}
 			} else {
-				logger.Debug("[UI:AppSession] Session not found, creating a new one")
+				slog.Debug("App session not found, creating a new one")
 				session, err = m.store.CreateAppSession()
 				if err != nil {
 					html.ServerError(w, r, err)
@@ -78,8 +86,6 @@ func (m *middleware) handleAppSession(next http.Handler) http.Handler {
 			}
 
 			http.SetCookie(w, cookie.New(cookie.CookieAppSessionID, session.ID, config.Opts.HTTPS, config.Opts.BasePath()))
-		} else {
-			logger.Debug("[UI:AppSession] %s", session)
 		}
 
 		if r.Method == http.MethodPost {
@@ -87,7 +93,11 @@ func (m *middleware) handleAppSession(next http.Handler) http.Handler {
 			headerValue := r.Header.Get("X-Csrf-Token")
 
 			if session.Data.CSRF != formValue && session.Data.CSRF != headerValue {
-				logger.Error(`[UI:AppSession] Invalid or missing CSRF token: Form="%s", Header="%s"`, formValue, headerValue)
+				slog.Warn("Invalid or missing CSRF token",
+					slog.Any("url", r.RequestURI),
+					slog.String("form_csrf", formValue),
+					slog.String("header_csrf", headerValue),
+				)
 
 				if mux.CurrentRoute(r).GetName() == "checkLogin" {
 					html.Redirect(w, r, route.Path(m.router, "login"))
@@ -121,7 +131,10 @@ func (m *middleware) getAppSessionValueFromCookie(r *http.Request) *model.Sessio
 
 	session, err := m.store.AppSession(cookieValue)
 	if err != nil {
-		logger.Error("[UI:AppSession] %v", err)
+		slog.Debug("Unable to fetch app session from the database; another session will be created",
+			slog.Any("cookie_value", cookieValue),
+			slog.Any("error", err),
+		)
 		return nil
 	}
 
@@ -159,7 +172,10 @@ func (m *middleware) getUserSessionFromCookie(r *http.Request) *model.UserSessio
 
 	session, err := m.store.UserSessionByToken(cookieValue)
 	if err != nil {
-		logger.Error("[UI:UserSession] %v", err)
+		slog.Error("Unable to fetch user session from the database",
+			slog.Any("cookie_value", cookieValue),
+			slog.Any("error", err),
+		)
 		return nil
 	}
 
@@ -180,7 +196,11 @@ func (m *middleware) handleAuthProxy(next http.Handler) http.Handler {
 		}
 
 		clientIP := request.ClientIP(r)
-		logger.Info("[AuthProxy] [ClientIP=%s] Received authenticated requested for %q", clientIP, username)
+		slog.Debug("[AuthProxy] Received authenticated requested",
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("username", username),
+		)
 
 		user, err := m.store.UserByUsername(username)
 		if err != nil {
@@ -189,9 +209,13 @@ func (m *middleware) handleAuthProxy(next http.Handler) http.Handler {
 		}
 
 		if user == nil {
-			logger.Error("[AuthProxy] [ClientIP=%s] %q doesn't exist", clientIP, username)
-
 			if !config.Opts.IsAuthProxyUserCreationAllowed() {
+				slog.Debug("[AuthProxy] User doesn't exist and user creation is not allowed",
+					slog.Bool("authentication_failed", true),
+					slog.String("client_ip", clientIP),
+					slog.String("user_agent", r.UserAgent()),
+					slog.String("username", username),
+				)
 				html.Forbidden(w, r)
 				return
 			}
@@ -208,7 +232,13 @@ func (m *middleware) handleAuthProxy(next http.Handler) http.Handler {
 			return
 		}
 
-		logger.Info("[AuthProxy] [ClientIP=%s] username=%s just logged in", clientIP, user.Username)
+		slog.Info("[AuthProxy] User authenticated successfully",
+			slog.Bool("authentication_successful", true),
+			slog.String("client_ip", clientIP),
+			slog.String("user_agent", r.UserAgent()),
+			slog.Int64("user_id", user.ID),
+			slog.String("username", user.Username),
+		)
 
 		m.store.SetLastLogin(user.ID)
 

internal/ui/oauth2_callback.go

@@ -6,6 +6,7 @@ package ui // import "miniflux.app/v2/internal/ui"
 import (
 	"crypto/subtle"
 	"errors"
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/config"
@@ -14,7 +15,6 @@ import (
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
 	"miniflux.app/v2/internal/locale"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/ui/session"
 )
@@ -26,41 +26,48 @@ func (h *handler) oauth2Callback(w http.ResponseWriter, r *http.Request) {
 
 	provider := request.RouteStringParam(r, "provider")
 	if provider == "" {
-		logger.Error("[OAuth2] Invalid or missing provider")
+		slog.Warn("Invalid or missing OAuth2 provider")
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}
 
 	code := request.QueryStringParam(r, "code", "")
 	if code == "" {
-		logger.Error("[OAuth2] No code received on callback")
+		slog.Warn("No code received on OAuth2 callback")
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}
 
 	state := request.QueryStringParam(r, "state", "")
 	if subtle.ConstantTimeCompare([]byte(state), []byte(request.OAuth2State(r))) == 0 {
-		logger.Error(`[OAuth2] Invalid state value: got "%s" instead of "%s"`, state, request.OAuth2State(r))
+		slog.Warn("Invalid OAuth2 state value received",
+			slog.String("expected", request.OAuth2State(r)),
+			slog.String("received", state),
+		)
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}
 
 	authProvider, err := getOAuth2Manager(r.Context()).FindProvider(provider)
 	if err != nil {
-		logger.Error("[OAuth2] %v", err)
+		slog.Error("Unable to initialize OAuth2 provider",
+			slog.String("provider", provider),
+			slog.Any("error", err),
+		)
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}
 
 	profile, err := authProvider.GetProfile(r.Context(), code, request.OAuth2CodeVerifier(r))
 	if err != nil {
-		logger.Error("[OAuth2] %v", err)
+		slog.Warn("Unable to get OAuth2 profile from provider",
+			slog.String("provider", provider),
+			slog.Any("error", err),
+		)
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}
 
-	logger.Info("[OAuth2] [ClientIP=%s] Successful auth for %s", clientIP, profile)
-
 	if request.IsAuthenticated(r) {
 		loggedUser, err := h.store.UserByID(request.UserID(r))
 		if err != nil {
@@ -69,7 +76,11 @@ func (h *handler) oauth2Callback(w http.ResponseWriter, r *http.Request) {
 		}
 
 		if h.store.AnotherUserWithFieldExists(loggedUser.ID, profile.Key, profile.ID) {
-			logger.Error("[OAuth2] User #%d cannot be associated because it is already associated with another user", loggedUser.ID)
+			slog.Error("Oauth2 user cannot be associated because it is already associated with another user",
+				slog.Int64("user_id", loggedUser.ID),
+				slog.String("oauth2_provider", provider),
+				slog.String("oauth2_profile_id", profile.ID),
+			)
 			sess.NewFlashErrorMessage(printer.Printf("error.duplicate_linked_account"))
 			html.Redirect(w, r, route.Path(h.router, "settings"))
 			return
@@ -119,7 +130,13 @@ func (h *handler) oauth2Callback(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	logger.Info("[OAuth2] [ClientIP=%s] username=%s (%s) just logged in", clientIP, user.Username, profile)
+	slog.Info("User authenticated successfully using OAuth2",
+		slog.Bool("authentication_successful", true),
+		slog.String("client_ip", clientIP),
+		slog.String("user_agent", r.UserAgent()),
+		slog.Int64("user_id", user.ID),
+		slog.String("username", user.Username),
+	)
 
 	h.store.SetLastLogin(user.ID)
 	sess.SetLanguage(user.Language)

internal/ui/oauth2_redirect.go

@@ -4,12 +4,12 @@
 package ui // import "miniflux.app/v2/internal/ui"
 
 import (
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/oauth2"
 	"miniflux.app/v2/internal/ui/session"
 )
@@ -19,14 +19,17 @@ func (h *handler) oauth2Redirect(w http.ResponseWriter, r *http.Request) {
 
 	provider := request.RouteStringParam(r, "provider")
 	if provider == "" {
-		logger.Error("[OAuth2] Invalid or missing provider: %s", provider)
+		slog.Warn("Invalid or missing OAuth2 provider")
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}
 
 	authProvider, err := getOAuth2Manager(r.Context()).FindProvider(provider)
 	if err != nil {
-		logger.Error("[OAuth2] %v", err)
+		slog.Error("Unable to initialize OAuth2 provider",
+			slog.String("provider", provider),
+			slog.Any("error", err),
+		)
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}

internal/ui/oauth2_unlink.go

@@ -4,13 +4,13 @@
 package ui // import "miniflux.app/v2/internal/ui"
 
 import (
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
 	"miniflux.app/v2/internal/locale"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/ui/session"
 )
 
@@ -18,14 +18,17 @@ func (h *handler) oauth2Unlink(w http.ResponseWriter, r *http.Request) {
 	printer := locale.NewPrinter(request.UserLanguage(r))
 	provider := request.RouteStringParam(r, "provider")
 	if provider == "" {
-		logger.Info("[OAuth2] Invalid or missing provider")
+		slog.Warn("Invalid or missing OAuth2 provider")
 		html.Redirect(w, r, route.Path(h.router, "login"))
 		return
 	}
 
 	authProvider, err := getOAuth2Manager(r.Context()).FindProvider(provider)
 	if err != nil {
-		logger.Error("[OAuth2] %v", err)
+		slog.Error("Unable to initialize OAuth2 provider",
+			slog.String("provider", provider),
+			slog.Any("error", err),
+		)
 		html.Redirect(w, r, route.Path(h.router, "settings"))
 		return
 	}

internal/ui/opml_upload.go

@@ -4,6 +4,7 @@
 package ui // import "miniflux.app/v2/internal/ui"
 
 import (
+	"log/slog"
 	"net/http"
 
 	"miniflux.app/v2/internal/config"
@@ -11,14 +12,14 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/reader/opml"
 	"miniflux.app/v2/internal/ui/session"
 	"miniflux.app/v2/internal/ui/view"
 )
 
 func (h *handler) uploadOPML(w http.ResponseWriter, r *http.Request) {
-	user, err := h.store.UserByID(request.UserID(r))
+	loggedUserID := request.UserID(r)
+	user, err := h.store.UserByID(loggedUserID)
 	if err != nil {
 		html.ServerError(w, r, err)
 		return
@@ -26,17 +27,20 @@ func (h *handler) uploadOPML(w http.ResponseWriter, r *http.Request) {
 
 	file, fileHeader, err := r.FormFile("file")
 	if err != nil {
-		logger.Error("[UI:UploadOPML] %v", err)
+		slog.Error("OPML file upload error",
+			slog.Int64("user_id", loggedUserID),
+			slog.Any("error", err),
+		)
+
 		html.Redirect(w, r, route.Path(h.router, "import"))
 		return
 	}
 	defer file.Close()
 
-	logger.Debug(
-		"[UI:UploadOPML] User #%d uploaded this file: %s (%d bytes)",
-		user.ID,
-		fileHeader.Filename,
-		fileHeader.Size,
+	slog.Info("OPML file uploaded",
+		slog.Int64("user_id", loggedUserID),
+		slog.String("file_name", fileHeader.Filename),
+		slog.Int64("file_size", fileHeader.Size),
 	)
 
 	sess := session.New(h.store, request.SessionID(r))
@@ -62,7 +66,8 @@ func (h *handler) uploadOPML(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *handler) fetchOPML(w http.ResponseWriter, r *http.Request) {
-	user, err := h.store.UserByID(request.UserID(r))
+	loggedUserID := request.UserID(r)
+	user, err := h.store.UserByID(loggedUserID)
 	if err != nil {
 		html.ServerError(w, r, err)
 		return
@@ -74,10 +79,9 @@ func (h *handler) fetchOPML(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	logger.Debug(
-		"[UI:FetchOPML] User #%d fetching this URL: %s",
-		user.ID,
-		url,
+	slog.Info("Fetching OPML file remotely",
+		slog.Int64("user_id", loggedUserID),
+		slog.String("opml_file_url", url),
 	)
 
 	sess := session.New(h.store, request.SessionID(r))

internal/ui/proxy.go

@@ -8,6 +8,7 @@ import (
 	"crypto/sha256"
 	"encoding/base64"
 	"errors"
+	"log/slog"
 	"net/http"
 	"time"
 
@@ -16,7 +17,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response"
 	"miniflux.app/v2/internal/http/response/html"
-	"miniflux.app/v2/internal/logger"
 )
 
 func (h *handler) mediaProxy(w http.ResponseWriter, r *http.Request) {
@@ -29,19 +29,19 @@ func (h *handler) mediaProxy(w http.ResponseWriter, r *http.Request) {
 	encodedDigest := request.RouteStringParam(r, "encodedDigest")
 	encodedURL := request.RouteStringParam(r, "encodedURL")
 	if encodedURL == "" {
-		html.BadRequest(w, r, errors.New("No URL provided"))
+		html.BadRequest(w, r, errors.New("no URL provided"))
 		return
 	}
 
 	decodedDigest, err := base64.URLEncoding.DecodeString(encodedDigest)
 	if err != nil {
-		html.BadRequest(w, r, errors.New("Unable to decode this Digest"))
+		html.BadRequest(w, r, errors.New("unable to decode this digest"))
 		return
 	}
 
 	decodedURL, err := base64.URLEncoding.DecodeString(encodedURL)
 	if err != nil {
-		html.BadRequest(w, r, errors.New("Unable to decode this URL"))
+		html.BadRequest(w, r, errors.New("unable to decode this URL"))
 		return
 	}
 
@@ -55,7 +55,9 @@ func (h *handler) mediaProxy(w http.ResponseWriter, r *http.Request) {
 	}
 
 	mediaURL := string(decodedURL)
-	logger.Debug(`[Proxy] Fetching %q`, mediaURL)
+	slog.Debug("MediaProxy: Fetching remote resource",
+		slog.String("media_url", mediaURL),
+	)
 
 	req, err := http.NewRequest("GET", mediaURL, nil)
 	if err != nil {
@@ -82,19 +84,28 @@ func (h *handler) mediaProxy(w http.ResponseWriter, r *http.Request) {
 
 	resp, err := clt.Do(req)
 	if err != nil {
-		logger.Error(`[Proxy] Unable to initialize HTTP client: %v`, err)
+		slog.Error("MediaProxy: Unable to initialize HTTP client",
+			slog.String("media_url", mediaURL),
+			slog.Any("error", err),
+		)
 		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		return
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode == http.StatusRequestedRangeNotSatisfiable {
-		logger.Error(`[Proxy] Status Code is %d for URL %q`, resp.StatusCode, mediaURL)
+		slog.Warn("MediaProxy: "+http.StatusText(http.StatusRequestedRangeNotSatisfiable),
+			slog.String("media_url", mediaURL),
+			slog.Int("status_code", resp.StatusCode),
+		)
 		html.RequestedRangeNotSatisfiable(w, r, resp.Header.Get("Content-Range"))
 		return
 	}
 	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
-		logger.Error(`[Proxy] Status Code is %d for URL %q`, resp.StatusCode, mediaURL)
+		slog.Warn("MediaProxy: Unexpected response status code",
+			slog.String("media_url", mediaURL),
+			slog.Int("status_code", resp.StatusCode),
+		)
 		html.NotFound(w, r)
 		return
 	}

internal/ui/session_remove.go

@@ -9,14 +9,14 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 )
 
 func (h *handler) removeSession(w http.ResponseWriter, r *http.Request) {
 	sessionID := request.RouteInt64Param(r, "sessionID")
 	err := h.store.RemoveUserSessionByID(request.UserID(r), sessionID)
 	if err != nil {
-		logger.Error("[UI:RemoveSession] %v", err)
+		html.ServerError(w, r, err)
+		return
 	}
 
 	html.Redirect(w, r, route.Path(h.router, "sessions"))

internal/ui/settings_update.go

@@ -10,7 +10,6 @@ import (
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
 	"miniflux.app/v2/internal/locale"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
@@ -74,9 +73,7 @@ func (h *handler) updateSettings(w http.ResponseWriter, r *http.Request) {
 
 	err = h.store.UpdateUser(settingsForm.Merge(loggedUser))
 	if err != nil {
-		logger.Error("[UI:UpdateSettings] %v", err)
-		view.Set("errorMessage", "error.unable_to_update_user")
-		html.OK(w, r, view.Render("settings"))
+		html.ServerError(w, r, err)
 		return
 	}
 

internal/ui/subscription_submit.go

@@ -10,7 +10,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	feedHandler "miniflux.app/v2/internal/reader/handler"
 	"miniflux.app/v2/internal/reader/subscription"
@@ -61,15 +60,12 @@ func (h *handler) submitSubscription(w http.ResponseWriter, r *http.Request) {
 		subscriptionForm.AllowSelfSignedCertificates,
 	)
 	if findErr != nil {
-		logger.Error("[UI:SubmitSubscription] %q -> %s", subscriptionForm.URL, findErr)
 		v.Set("form", subscriptionForm)
 		v.Set("errorMessage", findErr)
 		html.OK(w, r, v.Render("add_subscription"))
 		return
 	}
 
-	logger.Debug("[UI:SubmitSubscription] %s", subscriptions)
-
 	n := len(subscriptions)
 	switch {
 	case n == 0:

internal/ui/ui.go

@@ -6,7 +6,6 @@ package ui // import "miniflux.app/v2/internal/ui"
 import (
 	"net/http"
 
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/storage"
 	"miniflux.app/v2/internal/template"
 	"miniflux.app/v2/internal/worker"
@@ -20,7 +19,7 @@ func Serve(router *mux.Router, store *storage.Storage, pool *worker.Pool) {
 
 	templateEngine := template.NewEngine(router)
 	if err := templateEngine.ParseTemplates(); err != nil {
-		logger.Fatal(`Unable to parse templates: %v`, err)
+		panic(err)
 	}
 
 	handler := &handler{router, store, templateEngine, pool}

internal/ui/user_remove.go

@@ -37,7 +37,7 @@ func (h *handler) removeUser(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if selectedUser.ID == loggedUser.ID {
-		html.BadRequest(w, r, errors.New("You cannot remove yourself"))
+		html.BadRequest(w, r, errors.New("you cannot remove yourself"))
 		return
 	}
 

internal/ui/user_save.go

@@ -9,7 +9,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/model"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
@@ -64,9 +63,7 @@ func (h *handler) saveUser(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if _, err := h.store.CreateUser(userCreationRequest); err != nil {
-		logger.Error("[UI:SaveUser] %v", err)
-		view.Set("errorMessage", "error.unable_to_create_user")
-		html.OK(w, r, view.Render("create_user"))
+		html.ServerError(w, r, err)
 		return
 	}
 

internal/ui/user_update.go

@@ -9,7 +9,6 @@ import (
 	"miniflux.app/v2/internal/http/request"
 	"miniflux.app/v2/internal/http/response/html"
 	"miniflux.app/v2/internal/http/route"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/ui/form"
 	"miniflux.app/v2/internal/ui/session"
 	"miniflux.app/v2/internal/ui/view"
@@ -64,9 +63,7 @@ func (h *handler) updateUser(w http.ResponseWriter, r *http.Request) {
 
 	userForm.Merge(selectedUser)
 	if err := h.store.UpdateUser(selectedUser); err != nil {
-		logger.Error("[UI:UpdateUser] %v", err)
-		view.Set("errorMessage", "error.unable_to_update_user")
-		html.OK(w, r, view.Render("edit_user"))
+		html.ServerError(w, r, err)
 		return
 	}
 

internal/worker/worker.go

@@ -4,10 +4,10 @@
 package worker // import "miniflux.app/v2/internal/worker"
 
 import (
+	"log/slog"
 	"time"
 
 	"miniflux.app/v2/internal/config"
-	"miniflux.app/v2/internal/logger"
 	"miniflux.app/v2/internal/metric"
 	"miniflux.app/v2/internal/model"
 	feedHandler "miniflux.app/v2/internal/reader/handler"
@@ -22,11 +22,17 @@ type Worker struct {
 
 // Run wait for a job and refresh the given feed.
 func (w *Worker) Run(c chan model.Job) {
-	logger.Debug("[Worker] #%d started", w.id)
+	slog.Debug("Worker started",
+		slog.Int("worker_id", w.id),
+	)
 
 	for {
 		job := <-c
-		logger.Debug("[Worker #%d] Received feed #%d for user #%d", w.id, job.FeedID, job.UserID)
+		slog.Debug("Job received by worker",
+			slog.Int("worker_id", w.id),
+			slog.Int64("user_id", job.UserID),
+			slog.Int64("feed_id", job.FeedID),
+		)
 
 		startTime := time.Now()
 		refreshErr := feedHandler.RefreshFeed(w.store, job.UserID, job.FeedID, false)
@@ -40,7 +46,11 @@ func (w *Worker) Run(c chan model.Job) {
 		}
 
 		if refreshErr != nil {
-			logger.Error("[Worker] Refreshing the feed #%d returned this error: %v", job.FeedID, refreshErr)
+			slog.Warn("Unable to refresh a feed",
+				slog.Int64("user_id", job.UserID),
+				slog.Int64("feed_id", job.FeedID),
+				slog.Any("error", refreshErr),
+			)
 		}
 	}
 }

miniflux.1

@@ -1,5 +1,5 @@
 .\" Manpage for miniflux.
-.TH "MINIFLUX" "1" "July 21, 2023" "\ \&" "\ \&"
+.TH "MINIFLUX" "1" "September 24, 2023" "\ \&" "\ \&"
 
 .SH NAME
 miniflux \- Minimalist and opinionated feed reader
@@ -36,7 +36,7 @@ Create admin user\&.
 .PP
 .B \-debug
 .RS 4
-Show debug logs\&.
+Set log level to debug\&.
 .RE
 .PP
 .B \-flush-sessions
@@ -113,11 +113,6 @@ Environment variables override the values defined in the config file.
 
 .SH ENVIRONMENT
 .TP
-.B DEBUG
-Set the value to 1 to enable debug logs\&.
-.br
-Disabled by default\&.
-.TP
 .B FETCH_ODYSEE_WATCH_TIME
 Set the value to 1 to scrape video duration from Odysee website and
 use it as a reading time\&.
@@ -145,6 +140,21 @@ Display the date and time in log messages\&.
 .br
 Disabled by default\&.
 .TP
+.B LOG_FILE
+Supported values are "stderr", "stdout", or a file name\&.
+.br
+Default is "stderr"\&.
+.TP
+.B LOG_FORMAT
+Supported log formats are "text" or "json"\&.
+.br
+Default is "text"\&.
+.TP
+.B LOG_LEVEL
+Supported values are "debug", "info", "warning", or "error"\&.
+.br
+Default is "info"\&.
+.TP
 .B WORKER_POOL_SIZE
 Number of background workers\&.
 .br