adding docker-build job

.gitea/workflows/test-build.yaml

@@ -12,6 +12,7 @@ on:
       - main
     paths:
       - build-and-push/**
+      - docker-build/**
       - deploy-restart/**
       - kubectl-apply/**
       - ssh-deploy/**
@@ -110,6 +111,34 @@ jobs:
           echo "${MANIFEST}" | grep -q "linux/arm64" || { echo "missing linux/arm64"; exit 1; }
           echo "self-test PASSED: multi-arch image built and pushed"
 
+  test-build-only:
+    name: Build-only tiny multi-arch image (${{ matrix.runner }})
+    if: ${{ gitea.event_name != 'workflow_run' || gitea.event.workflow_run.conclusion == 'success' }}
+    runs-on: ${{ matrix.runner }}
+    strategy:
+      matrix:
+        runner: [runner-slim-amd64, runner-full-amd64, runner-slim-arm64, runner-full-arm64]
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Generate a minimal Dockerfile
+        shell: bash
+        run: |
+          mkdir -p _selftest
+          cat > _selftest/Dockerfile <<'EOF'
+          FROM alpine:3.20
+          RUN echo "pipeline-actions self-test build-only OK"
+          CMD ["true"]
+          EOF
+
+      - name: Build (no push) via composite action
+        uses: https://git.ivanch.me/ivanch/pipeline-actions/docker-build@main
+        with:
+          build_context: _selftest
+          build_dockerfile: Dockerfile
+          ssh_key: ${{ secrets.SSH_KEY_DOCKERBUILD }}
+
   test-k8s:
     name: Test Kubernetes actions (${{ matrix.runner }})
     if: ${{ gitea.event_name != 'workflow_run' || gitea.event.workflow_run.conclusion == 'success' }}