ci: implement a PR title linter

Author: alessfg

.github/pull_request_template.md

@@ -8,6 +8,7 @@ Before creating a PR, run through this checklist and mark each as complete:
 
 - [ ] I have read the [contributing guidelines](/CONTRIBUTING.md).
 - [ ] I have signed the [F5 Contributor License Agreement (CLA)](https://github.com/f5/.github/blob/main/CLA/cla-markdown.md).
+- [ ] The PR title follows the [Conventional Commits specification](https://www.conventionalcommits.org/en/v1.0.0/).
 - [ ] If applicable, I have added tests that prove my fix is effective or that my feature works.
 - [ ] If applicable, I have checked that any relevant tests pass after adding my changes.
 - [ ] I have updated any relevant documentation (e.g. [`README.md`](/README.md)).

.github/workflows/lint-pr-title.yml

@@ -0,0 +1,40 @@
+---
+name: Lint PR Title
+on:
+  pull_request_target:
+    types: [opened, edited, synchronize]
+jobs:
+  main:
+    name: Validate PR title
+    runs-on: ubuntu-22.04
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Check PR title
+        id: lint_pr_title
+        uses: amannn/action-semantic-pull-request@0723387faaf9b38adef4775cd42cfd5155ed6017 # v5.5.3
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Comment on the PR if the title doesn't follow the Conventional Commits specification
+        if: always() && (steps.lint_pr_title.outputs.error_message != null)
+        uses: marocchino/sticky-pull-request-comment@331f8f5b4215f0445d3c07b4967662a32a2d3e31 # v2.9.0
+        with:
+          header: pr-title-lint-error
+          message: |
+            Thank you for opening this pull request! 👋🏼
+
+            In order to streamline our release process and maintain a consistent commit history, we require pull request (PR) titles to follow the [Conventional Commits specification](https://www.conventionalcommits.org/en/v1.0.0/).
+
+            Based on our linter, it looks like your proposed title needs to be adjusted. Here's the error message we received:
+
+            ```
+            ${{ steps.lint_pr_title.outputs.error_message }}
+            ```
+
+      - name: Delete the previous comment once the PR title has been updated
+        if: ${{ steps.lint_pr_title.outputs.error_message == null }}
+        uses: marocchino/sticky-pull-request-comment@331f8f5b4215f0445d3c07b4967662a32a2d3e31 # v2.9.0
+        with:
+          header: pr-title-lint-error
+          delete: true