add MySql healthcheck to dependency for backend (#148)

Signed-off-by: Alvaro Carpio <alvanxp@outlook.com>

nginx-flask-mysql/docker-compose.yaml

@@ -4,6 +4,11 @@ services:
     image: mysql:8.0.19
     command: '--default-authentication-plugin=mysql_native_password'
     restart: always
+    healthcheck:
+      test: ["CMD", "mysqladmin", "ping", "-h", "127.0.0.1", "--silent"]
+      interval: 3s
+      retries: 5
+      start_period: 30s
     secrets:
       - db-password
     volumes:
@@ -26,11 +31,16 @@ services:
     networks:
       - backnet
       - frontnet
+    depends_on:
+      db:
+        condition: service_healthy
   proxy:
     build: proxy
     restart: always
     ports:
       - 80:80
+    depends_on: 
+      - backend
     networks:
       - frontnet
 volumes: