[#solution-on-git-push]
= GitOps (run actions on Git Push)

image::gitops.png[]

A really helpful thing to do with OliveTin is to have it run actions when you push to a Git repository. This is a great way to automate things like running tests, building your project, or deploying your code - this turns OliveTin into a powerful GitOps tool, or even a Continuous Integration tool.

This guide assumes that you are using a self-hosted Git repository, and uses a standard Git `post-receive` hook to trigger OliveTin actions.

[TIP]
====
**Using GitHub?** OliveTin has built-in support for GitHub webhooks with templates that make configuration simple. See xref:action_execution/onwebhook_github.adoc[GitHub Webhooks] for an easier approach that doesn't require writing hook scripts.
====

To set up OliveTin to run actions on Git push, you will need to:

1. Create a new OliveTin action that you want to run on push.
2. Set up a Git `post-receive` hook to trigger the OliveTin action.

== Create a New OliveTin Action

First, you will need to create a new OliveTin action that you want to run when you push to your Git repository. This could be anything you like - for example, running tests, building your project, or deploying your code. The example below is a simple action that echoes a message to the console:

[source,yaml]
.OliveTin `config.yaml`
----
actions:
  - title: Run on Git Push
    id: gitops
    icon: <iconify-icon icon="bi:git"></iconify-icon>
    shell: |
        echo "You just pushed commit $COMMIT to git, running action..."
        date
    arguments:
        - name: commit
          type: ascii
----

Note that OliveTin will expose all arguments as environment variables in uppercase as shown in the example above. You can of course use the `{{ commit }}` syntax instead and it will do the same thing.

== Add a Git hook script

The following below assumes that you have a Git repository initialized as a bare repository, at `/opt/myrepo.git`. If you have a different repository location, you will need to adjust the paths accordingly.

First, create a new file at `/opt/myrepo.git/hooks/post-receive` with the following contents:

[source,bash]
.Script: `myrepo.git/hooks/post-receive`
----
#!/bin/bash

read OLDREV NEWREV REFNAME

CHANGED_FILES=$(git diff --name-only $OLDREV $NEWREV)

commit_contains_path() {
        local filename=$1

        if echo "$CHANGED_FILES" | grep -q "$filename"; then
                return 0 # True
        else
                return 1 # False
        fi
}

function run_olivetin_action() {
        local ACTION_NAME=$1

        echo "Requesting OliveTin job $ACTION_NAME"

        OLIVETIN_REQUEST="$(cat <<EOF
{
  "actionId": "$ACTION_NAME",
  "arguments": [
        {
                "name": "commit",
                "value": "$NEWREV"
        }
  ]
}
EOF
)"

        exec curl -sS --json "$OLIVETIN_REQUEST" http://olivetin.example.com:1337/api/StartAction
}

if commit_contains_path "k8s-flux"; then
        run_olivetin_action "ServerConfiguration_Flux"

        exit
fi

if commit_contains_path "alert.rules"; then
        run_olivetin_action "ServerConfiguration_Prom"

        exit
fi

run_olivetin_action "gitops"
----

Make sure you make the script executable, and edit the last line of the script to point to your OliveTin instance.

[source,bash]
----
chmod +x /opt/myrepo.git/hooks/post-receive
----

Now, whenever you push to your Git repository, the `post-receive` hook will trigger the OliveTin action you created. You can see if the action was triggered by pushing to the git repository, and looking for output like this;

----
remote: {"executionTrackingId":"55c7371d-7a67-42a4-87d8-d5677b878186"}
----

This is the `executionTrackingId` of the action that was triggered. You can use this to track the progress of the action in the OliveTin UI.