[CI/CD] Refactor backports flow so that it can determine automatically where to do a backport based on labels

.github/scripts/common/lib.sh

@@ -508,6 +508,7 @@ validate_stable_tag() {
 }
 
 # Prepare docker stable tag form the polkadot stable tag
+#
 # input: tag (polkaodot-stableYYMM(-X) or polkadot-stableYYMM(-X)-rcX)
 # output: stableYYMM(-X) or stableYYMM(-X)-rcX
 prepare_docker_stable_tag() {
@@ -519,3 +520,22 @@ prepare_docker_stable_tag() {
       exit 1
   fi
 }
+
+# Parse names of the branches from the github labels based on the pattern
+#
+# input: labels (array of lables like ("A3-backport" "RO-silent" "A4-backport-stable2407" "A4-backport-stable2503"))
+# output: BRANCHES (array of the branch names)
+parse_branch_names_from_backport_labels() {
+  labels="$1"
+  BRANCHES=""
+
+  for label in $labels; do
+    if [[ "$label" =~ ^A4-backport-stable[0-9]{4}$ ]]; then
+      branch_name=$(sed 's/A4-backport-//' <<< "$label")
+      BRANCHES+=" ${branch_name}"
+    fi
+  done
+
+  BRANCHES=$(echo "$BRANCHES" | sed 's/^ *//')
+  echo "$BRANCHES"
+}

.github/workflows/command-backport.yml

@@ -13,34 +13,68 @@ permissions:
   actions: write # It may have to backport changes to the CI as well.
 
 jobs:
-  backport:
-    name: Backport pull request
+  check-labels:
     runs-on: ubuntu-latest
+    env:
+      GH_TOKEN: ${{ github.token }}
+    outputs:
+      LABELS: ${{ steps.check_labels.outputs.LABELS}}
+      found: ${{ steps.check_labels.outputs.found}}
 
     # The 'github.event.pull_request.merged' ensures that it got into master:
     if: >
       ( !startsWith(github.event.pull_request.base.ref, 'stable') ) &&
       (
         github.event_name == 'pull_request_target' &&
         github.event.pull_request.merged &&
-        github.event.pull_request.base.ref == 'master' &&
-        contains(github.event.pull_request.labels.*.name, 'A4-needs-backport')
+        github.event.pull_request.base.ref == 'master'
       )
     steps:
       - uses: actions/checkout@v4
 
+      - name: Check for backport labels
+        id: check_labels
+        run: |
+          LABELS=$(gh pr view ${{ github.event.pull_request.number }} --json labels --jq '.labels[].name')
+
+          if echo "$LABELS" | grep -q '^A4-backport-stable'; then
+            echo "found=true" >> $GITHUB_OUTPUT
+            readarray -t labels_array <<< "$LABELS"
+            echo "LABELS=${labels_array[@]}" >> $GITHUB_OUTPUT
+          else
+            echo "found=false" >> $GITHUB_OUTPUT
+          fi
+
+
+  backport:
+    name: Backport pull request
+    runs-on: ubuntu-latest
+    needs: [ check-labels ]
+    if: ${{ needs.check-labels.outputs.found  == 'true' }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Get branches to backport to
+        id: branches
+        run: |
+          . ./.github/scripts/common/lib.sh
+
+          LABELS="${{ needs.check-labels.outputs.LABELS }}"
+          BACKPORT_BRANCHES=$(parse_branch_names_from_backport_labels "$LABELS")
+          echo "BACKPORT_BRANCHES=${BACKPORT_BRANCHES}" >> $GITHUB_OUTPUT
+
       - name: Generate token
         id: generate_token
         uses: actions/create-github-app-token@v1
         with:
-          app_id: ${{ secrets.RELEASE_BACKPORT_AUTOMATION_APP_ID }}
-          private_key: ${{ secrets.RELEASE_BACKPORT_AUTOMATION_APP_PRIVATE_KEY }}
+          app-id: ${{ secrets.RELEASE_BACKPORT_AUTOMATION_APP_ID }}
+          private-key: ${{ secrets.RELEASE_BACKPORT_AUTOMATION_APP_PRIVATE_KEY }}
 
       - name: Create backport pull requests
         uses: korthout/backport-action@v3
         id: backport
         with:
-          target_branches: stable2407 stable2409 stable2412 stable2503
+          target_branches: ${{ steps.branches.outputs.BACKPORT_BRANCHES }}
           merge_commits: skip
           github_token: ${{ steps.generate_token.outputs.token }}
           pull_description: |
@@ -59,6 +93,7 @@ jobs:
               "conflict_resolution": "draft_commit_conflicts"
             }
           copy_assignees: true
+          label_pattern: ^A4-backport-stable
 
       - name: Label Backports
         if: ${{ steps.backport.outputs.created_pull_numbers != '' }}
@@ -86,11 +121,11 @@ jobs:
             const reviewer = '${{ github.event.pull_request.user.login }}';
 
             for (const pullNumber of pullNumbers) {
-              await github.pulls.requestReviewers({
+              await github.rest.pulls.requestReviewers({
                 owner: context.repo.owner,
                 repo: context.repo.repo,
                 pull_number: parseInt(pullNumber),
-                reviewers: [ reviewer ]
+                reviewers: [reviewer]
               });
               console.log(`Requested review from ${reviewer} for PR #${pullNumber}`);
             }

docs/BACKPORT.md

@@ -6,7 +6,11 @@ Backports should only be used to fix bugs or security issues - never to introduc
 ## Steps
 
 1. Fix a bug through a PR that targets `master`.
-2. Add label `A4-needs-backport` to the PR.
+2. Add label related to the branch to wich to backport changes to the PR.
+    - `A4-backport-stable2407`
+    - `A4-backport-stable2409`
+    - `A4-backport-stable2412`
+    - `A4-backport-stable2503`
 3. Merge the PR into `master`.
 4. Wait for the bot to open the backport PR.
 5. Ensure the change is audited or does not need audit.