build: Use commitlint to enfore conventional commits

`commitlint` has a better CLI, which allows to enforce
conventional commits in a GitHub Actions pipeline.

.commitlintrc.yml

@@ -0,0 +1,17 @@
+# SPDX-FileCopyrightText: Copyright DB Netz AG and contributors
+# SPDX-License-Identifier: CC0-1.0
+rules:
+  body-leading-blank: [2, always]
+  footer-leading-blank: [2, always]
+  scope-case: [2, always, lower-case]
+  subject-case: [2, always, sentence-case]
+  subject-empty: [2, never]
+  subject-full-stop: [2, never, .]
+  subject-max-length: [2, always, 72]
+  type-empty: [2, never]
+  type-enum:
+    [
+      2,
+      always,
+      [build, chore, ci, docs, feat, fix, merge, perf, refactor, revert, test],
+    ]

.github/workflows/commits.yml

@@ -0,0 +1,57 @@
+# SPDX-FileCopyrightText: Copyright DB Netz AG and contributors
+# SPDX-License-Identifier: CC0-1.0
+
+name: commits
+
+on:
+  pull_request:
+    branches: [main]
+
+jobs:
+  conventional-commits:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+      - name: Install commitlint
+        run: npm install -g @commitlint/cli
+      - name: Validate commit messages
+        id: conventional-commits
+        env:
+          SHA_FROM: ${{ github.event.pull_request.base.sha }}
+          SHA_TO: ${{ github.event.pull_request.head.sha }}
+        run: |
+          delim="_EOF_$(uuidgen)"
+          echo "validation-result<<$delim" >> "$GITHUB_OUTPUT"
+          r=0
+          commitlint --from "$SHA_FROM" --to "$SHA_TO" >> "$GITHUB_OUTPUT" 2>&1 || r=$?
+          echo "$delim" >> "$GITHUB_OUTPUT"
+          exit $r
+      - name: Post comment if validation failed
+        if: always() && steps.conventional-commits.outcome == 'failure'
+        uses: actions/github-script@v6
+        env:
+          TEXT: |-
+            The pull request does not conform to the conventional commit specification. Please ensure that your commit messages follow the spec: <https://www.conventionalcommits.org/>.
+            We also strongly recommend that you set up your development environment with pre-commit, as described in our [Developer documentation](https://dsd-dbs.github.io/capella-collab-manager/development/). This will run all the important checks right before you commit your changes, and avoids lengthy CI wait time and round trips.
+
+            This is the commit validation log:
+            ```
+            ${{ steps.conventional-commits.outputs.validation-result }}
+            ```
+
+            Here are some examples of valid commit messages:
+            ```
+            build: Bump frontend versions
+            docs(user): Add model creation workflow
+            feat: Add a monitoring dashboard
+            ```
+        with:
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: process.env.TEXT
+            })

.pre-commit-config.yaml

@@ -153,10 +153,11 @@ repos:
         types: []
         exclude: '.+\.spec(-helper)?\.ts$'
         types_or: ["html", "ts"]
-  - repo: https://github.com/qoomon/git-conventional-commits
-    rev: v2.6.7
+  - repo: https://github.com/alessandrojcm/commitlint-pre-commit-hook
+    rev: v9.11.0
     hooks:
-      - id: conventional-commits
+      - id: commitlint
+        stages: [commit-msg]
   - repo: https://github.com/asottile/pyupgrade
     rev: v3.15.0
     hooks: