Docker image stable

.github/workflows/docker-stable.yml

@@ -0,0 +1,51 @@
+# From:
+  # https://www.docker.com/blog/docker-github-actions/
+  # https://github.com/metcalfc/docker-action-examples
+
+name: Docker image stable
+
+on:
+  push:
+    tags:
+      - '*'
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Cache Docker layers
+        uses: actions/cache@v2
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
+
+      - name: Login to ghcr
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GHCR_TOKEN }}
+
+      - name: Get the version
+        id: get_version
+        run: echo ::set-output name=VERSION::${GITHUB_REF#refs/tags/}
+
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          builder: ${{ steps.buildx.outputs.name }}
+          context: ./docker
+          file: ./docker/Dockerfile
+          build-args: |
+            PHPSTAN_VERSION=${{ steps.get_version.outputs.VERSION }}
+          push: true
+          tags: ghcr.io/phpstan/phpstan:latest,ghcr.io/phpstan/phpstan:0.12,ghcr.io/phpstan/phpstan:${{ steps.get_version.outputs.VERSION }}