[BXMSPROD-1892] Automated pull request backporting workflow (#633)

* Automated pull request backporting workflow

* Added backporting guidance in pull_request_template.md

.github/pull_request_template.md

@@ -45,3 +45,19 @@ How to retest this PR or trigger a specific build:
 
 * <b>an upstream build</b> please add comment: <b>Jenkins run upstream</b>
 </details>
+
+<details>
+<summary>
+How to backport a pull request to a different branch?
+</summary>
+
+In order to automatically create a **backporting pull request** please add one or more labels having the following format `backport-<branch-name>`, where `<branch-name>` is the name of the branch where the pull request must be backported to (e.g., `backport-7.67.x` to backport the original PR to the `7.67.x` branch).
+
+> **NOTE**: **backporting** is an action aiming to move a change (usually a commit) from a branch (usually the main one) to another one, which is generally referring to a still maintained release branch. Keeping it simple: it is about to move a specific change or a set of them from one branch to another.
+
+Once the original pull request is successfully merged, the automated action will create one backporting pull request per each label (with the previous format) that has been added.
+
+If something goes wrong, the author will be notified and at this point a manual backporting is needed.
+
+> **NOTE**: this automated backporting is triggered whenever a pull request on `main` branch is labeled or closed, but both conditions must be satisfied to get the new PR created.
+</details>

.github/workflows/pr-backporting.yml

@@ -0,0 +1,43 @@
+name: Pull Request Backporting
+
+on:
+ pull_request_target:
+ types: [closed, labeled]
+ branches:
+ - main
+
+env:
+ GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+jobs:
+ compute-targets:
+ if: ${{ github.event.pull_request.state == 'closed' && github.event.pull_request.merged }}
+ runs-on: ubuntu-latest
+ outputs:
+ target-branches: ${{ steps.set-targets.outputs.targets }}
+ env:
+ LABELS: ${{ toJSON(github.event.pull_request.labels) }}
+ steps:
+ - name: Set target branches
+ id: set-targets
+ uses: kiegroup/droolsjbpm-build-bootstrap/.ci/actions/parse-labels@main
+ with:
+ labels: ${LABELS}
+
+ backporting:
+ if: ${{ github.event.pull_request.state == 'closed' && github.event.pull_request.merged && needs.compute-targets.outputs.target-branches != '[]' }}
+ name: "[${{ matrix.target-branch }}] - Backporting"
+ runs-on: ubuntu-latest
+ needs: compute-targets
+ strategy:
+ matrix: 
+ target-branch: ${{ fromJSON(needs.compute-targets.outputs.target-branches) }}
+ fail-fast: true
+ env:
+ REVIEWERS: ${{ toJSON(github.event.pull_request.requested_reviewers) }}
+ steps:
+ - name: Backporting
+ uses: kiegroup/droolsjbpm-build-bootstrap/.ci/actions/backporting@main
+ with:
+ target-branch: ${{ matrix.target-branch }}
+ additional-reviewers: ${REVIEWERS}