Experiment: Lint Dockerfiles using hadolint

.github/workflows/lint.yml

@@ -0,0 +1,64 @@
+name: Lint
+on: 
+  pull_request:
+    paths:
+      - '**/Dockerfile'
+
+jobs:
+  prepare:
+    name: Generate matrix
+    runs-on: ubuntu-22.04
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@v38
+        with:
+          json: true
+          escapepath: false
+          files: |
+            **/Dockerfile
+
+      - id: set-matrix
+        run: echo "matrix={\"dockerfile\":${{ steps.changed-files.outputs.all_changed_files }}}" >> "$GITHUB_OUTPUT"
+
+  hadolint:
+    name: Hadolint
+    needs: prepare
+    runs-on: ubuntu-latest
+    strategy:
+      matrix: ${{fromJson(needs.prepare.outputs.matrix)}}
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: hadolint/hadolint-action@v3.1.0
+        id: hadolint
+        continue-on-error: true
+        with:
+          verbose: true
+          dockerfile: ${{matrix.dockerfile}}
+
+      - name: Update Pull Request
+        uses: actions/github-script@v6
+        if: github.event_name == 'pull_request'
+        with:
+          script: |
+            const output = `
+            #### Hadolint: \`${{ steps.hadolint.outcome }}\`
+            \`\`\`
+            ${process.env.HADOLINT_RESULTS}
+            \`\`\`
+            `;
+
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: output
+            })

images/kube-proxy/v1.28.2/Dockerfile

@@ -1,3 +1,5 @@
+# dummy change to trigger workflow
+
 FROM docker.io/library/golang:1.20.8-alpine3.18 as binary
 
 RUN apk add --no-cache cmd:make cmd:bash cmd:rsync