Add CLA and Signed-off-by checks (#40)

Signed-off-by: Peter Sabaini <peter.sabaini@canonical.com>

Author: sabaini

.github/workflows/commits.yml

@@ -0,0 +1,33 @@
+name: Commits
+on:
+  - pull_request
+
+permissions:
+  contents: read
+
+jobs:
+  cla-check:
+    permissions:
+      pull-requests: read
+    name: Canonical CLA signed
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Check if CLA signed
+        uses: canonical/has-signed-canonical-cla@v2
+
+  dco-check:
+    permissions:
+      pull-requests: read  # for tim-actions/get-pr-commits to get list of commits from the PR
+    name: Signed-off-by (DCO)
+    runs-on: ubuntu-20.04
+    steps:
+    - name: Get PR Commits
+      id: 'get-pr-commits'
+      uses: tim-actions/get-pr-commits@master
+      with:
+        token: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Check that all commits are signed-off
+      uses: tim-actions/dco@master
+      with:
+        commits: ${{ steps.get-pr-commits.outputs.commits }}