Update versions file automation (#4512)

* Fix missing snapshots due to not fetched branches
* Improve PR description + add the version requirements to the
description/commit message

.github/workflows/bump-agent-versions.yml

@@ -11,6 +11,10 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          # no depth limit
+          # so, we can generate snapshot versions based on release branches
+          fetch-depth: 0
 
       - name: Set up Go
         uses: actions/setup-go@v4
@@ -20,16 +24,17 @@ jobs:
       - name: Set up branch
         run: git checkout -b update-agent-versions-$GITHUB_RUN_ID
 
-      - name: Update the agent version file
+      - name: Install mage
         uses: magefile/mage-action@v3
         with:
           version: v1.13.0
-          args: integration:updateVersions
+          install-only: true
 
-      - name: Check for file changes
+      - name: Update versions file
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
+          version_requirements=$(mage integration:updateVersions)
           changes=$(git status -s -uno .agent-versions.json)
           if [ -z "$changes" ]
           then
@@ -46,7 +51,7 @@ jobs:
             git config --global user.name 'apmmachine'
             git config --global user.email '[email protected]'
             git add ".agent-versions.json"
-            git commit -m "[$GITHUB_REF_NAME](automation) Update .agent-versions.json" -m "This file is used for picking agent versions in integration tests. It's content is based on the reponse from https://artifacts-api.elastic.co/v1/versions/"
+            git commit -m "[$GITHUB_REF_NAME](automation) Update .agent-versions.json" -m "This file is used for picking agent versions in integration tests.\n\nThe file's content is based on responses from https://www.elastic.co/api/product_versions and https://snapshots.elastic.co\n\nThe current update is generated based on the following requirements:\n\`\`\`json\n$version_requirements\n\`\`\`"
             git push --set-upstream origin "update-agent-versions-$GITHUB_RUN_ID"
             gh pr create \
               --base "$GITHUB_REF_NAME" \

magefile.go

@@ -1612,7 +1612,7 @@ func (Integration) UpdateVersions(ctx context.Context) error {
 		SnapshotBranches: branches,
 	}
 	b, _ := json.MarshalIndent(reqs, "", "  ")
-	fmt.Printf("Current version requirements: \n%s\n", b)
+	fmt.Println(string(b))
 
 	pvc := pv.NewProductVersionsClient()
 	sc := snapshots.NewSnapshotsClient()