Add a new check-commits CI job using gitlint

.github/workflows/main.yml

@@ -57,6 +57,25 @@ jobs:
     - name: Run checks
       run: make check
 
+  # Check commit messages (in particular enforce Signed-off-by)
+  check-commits:
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request'
+    steps:
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
+      with:
+        fetch-depth: 0
+        ref: ${{ github.event.pull_request.head.sha }}
+    - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405
+      with:
+        python-version: '3.13'
+    - name: Install gitlint
+      run: |
+        python3 -m venv venv.gitlint
+        ./venv.gitlint/bin/pip install gitlint==0.19.1
+    - name: Run gitlint
+      run: ./venv.gitlint/bin/gitlint -C .gitlint --commits origin/master.. lint
+
   # Run the test suite in a container per-ceph-codename
   test-suite:
     name: test-suite (${{ matrix.ceph_version }}${{ matrix.go_version != needs.go-versions.outputs.latest && format(', go{0}', matrix.go_version) || '' }})

.gitlint

@@ -0,0 +1,24 @@
+[general]
+verbosity=3
+regex-style-search=true
+contrib=contrib-body-requires-signed-off-by
+
+[title-max-length]
+line-length=72
+
+[title-must-not-contain-word]
+# Comma-separated list of words that should not occur in the title. Matching is case
+# insensitive. It's fine if the keyword occurs as part of a larger word (so "WIPING"
+# will not cause a violation, but "WIP: my title" will).
+words=wip,WIP
+
+[title-match-regex]
+# python-style regex that the commit-msg title must match
+# Note that the regex can contradict with other rules if not used correctly
+# (e.g. title-must-not-contain-word).
+regex=^.{2,32}: .*
+
+[ignore-body-lines]
+# do not enforce the default body line length checks on lines that appear to be
+# HTTP(S) URLs.
+regex=https?://