Chore: update changelog workflow (#90608)

* try integrating

* pass tags

* change section order

* use better terminology

* one more attempt

* keep delimiters

* attempt to patch changelog

* quotes, bash quotes...

* use proper content file

* parens around date

* time for a pr

* first checkout, then create user

* add latest input

* git push

* use square brackets

* formatting

* update release-pr

* fix typo

* try sparse checkout

* fetch depth zero

* clean up after changelog generator

.github/workflows/release-pr.yml

@@ -30,7 +30,7 @@ on:
         type: bool
 
 permissions:
-  content: write
+  contents: write
   pull-requests: write
 
 jobs:
@@ -39,44 +39,103 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository == 'grafana/grafana'
     steps:
+
+      - name: Generate bot token
+        id: generate_token
+        uses: tibdex/github-app-token@b62528385c34dbc9f38e5f4225ac829252d1ea92
+        with:
+          app_id: ${{ secrets.GRAFANA_DELIVERY_BOT_APP_ID }}
+          private_key: ${{ secrets.GRAFANA_DELIVERY_BOT_APP_PEM }}
+
       - name: Checkout Grafana
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          fetch-tags: true
+
       - name: Configure git user
         run: |
           git config --local user.name "github-actions[bot]"
           git config --local user.email "github-actions[bot]@users.noreply.github.com"
           git config --local --add --bool push.autoSetupRemote true
+
       - name: Create branch
         run: git checkout -b "release/${{ github.run_id }}/${{ inputs.version }}"
+
       - name: Generate changelog
-        run: git commit --allow-empty -m "Update changelog placeholder"
+        id: changelog
+        uses: ./.github/workflows/actions/changelog
+        with:
+          github_token: ${{ steps.generate_token.outputs.token }}
+          target: v${{ inputs.version }}
+          output_file: changelog_items.md
+
+      - name: Patch CHANGELOG.md
+        run: |
+          # Prepare CHANGELOG.md content with version delimiters
+          (
+            echo
+            echo "# ${{ inputs.version}} ($(date '+%F'))"
+            echo
+            cat changelog_items.md
+          ) > CHANGELOG.part
+
+          # Check if a version exists in the changelog
+          if grep -q "<!-- ${{ inputs.version}} START" CHANGELOG.md ; then
+            # Replace the content between START and END delimiters
+            echo "Version ${{ inputs.version }} is found in the CHANGELOG.md, patching contents..."
+            sed -i -e '/${{ inputs.version }} START/,/${{ inputs.version }} END/{//!d;}' \
+                   -e '/${{ inputs.version }} START/r CHANGELOG.part' CHANGELOG.md
+          else
+            # Prepend changelog part to the main changelog file
+            echo "Version ${{ inputs.version }} not found in the CHANGELOG.md"
+            (
+              echo "<!-- ${{ inputs.version }} START -->"
+              cat CHANGELOG.part
+              echo "<!-- ${{ inputs.version }} END -->"
+              cat CHANGELOG.md
+            ) > CHANGELOG.tmp
+            mv CHANGELOG.tmp CHANGELOG.md
+          fi
+
+          rm -f CHANGELOG.part changelog_items.md
+
+          git diff CHANGELOG.md
+
+      - name: Commit CHANGELOG.md changes
+        run: git commit --allow-empty -m "Update changelog placeholder" CHANGELOG.md
+
       - name: Update package.json versions
         uses: ./pkg/build/actions/bump-version
         with:
           version: ${{ inputs.version }}
-      - name: add package.json changes
+
+      - name: Add package.json changes
         run: |
           git add .
           git commit -m "Update version to ${{ inputs.version }}"
-      - name: git push
+
+      - name: Git push
         if: ${{ inputs.dry_run }} != true
         run: git push
+
       - name: Create PR without backports
         if: "${{ inputs.backport == '' }}"
         run: >
           gh pr create \
-            $( (( ${{ inputs.latest }} == "true" )) && printf %s '-l "release/latest"') \
+            $( [ "x${{ inputs.latest }}" == "xtrue" ] && printf %s '-l "release/latest"') \
             --dry-run=${{ inputs.dry_run }} \
             -B "${{ inputs.target }}" \
             --title "Release: ${{ inputs.version }}" \
             --body "These code changes must be merged after a release is complete"
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Create PR with backports
         if: "${{ inputs.backport != '' }}"
         run: >
           gh pr create \
-            $( (( ${{ inputs.latest }} == "true" )) && printf %s '-l "release/latest"') \
+            $( [ "x${{ inputs.latest }}" == "xtrue" ] && printf %s '-l "release/latest"') \
             -l "backport ${{ inputs.backport }}" \
             -l "product-approved" \
             --dry-run=${{ inputs.dry_run }} \