Attempt to speed up PR image builds by sharing a cache (#1844)

docker/setup-buildx-action actually provides first-class support for
the GitHub Actions cache (though experimental). This should make builds
much faster. Previous configuration wasn't properly configuring caching,
as far as I can tell.

This also takes advantage of GitHub Actions matrix support to more
concisely express the build parameters then execute the same steps on
them, which makes it clearer that the builds are all fundamentally doing
the same thing.

.github/workflows/pr_release.yaml

@@ -7,165 +7,55 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  build-executor-slim:
+  build-images:
     env:
-      GITHUB_SHA: ${{ github.sha }}
-      GITHUB_REF: ${{ github.ref }}
       PLATFORMS: "linux/amd64,linux/arm64,linux/s390x,linux/ppc64le"
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        image:
+        - executor
+        - executor-debug
+        - executor-slim
+        - warmer
+
+        include:
+        - image: executor
+          dockerfile: ./deploy/Dockerfile
+          platforms: linux/amd64,linux/arm64
+          name: gcr.io/kaniko-project/executor:${{ github.sha }}
+
+        - image: executor-debug
+          dockerfile: ./deploy/Dockerfile_debug
+          platforms: linux/amd64,linux/arm64
+          name: gcr.io/kaniko-project/executor:${{ github.sha }}-debug
+
+        - image: executor-slim
+          dockerfile: ./deploy/Dockerfile_slim
+          platforms: linux/amd64,linux/arm64,linux/s390x,linux/ppc64le
+          name: gcr.io/kaniko-project/executor:${{ github.sha }}-slim
+
+        - image: warmer
+          dockerfile: ./deploy/Dockerfile_warmer
+          name: gcr.io/kaniko-project/warmer:${{ github.sha }}
+          platforms: linux/amd64,linux/arm64
+
     steps:
-    - name: Clone source code
-      uses: actions/checkout@v2
+    - uses: actions/checkout@v2
 
-    - name: Get the tags
-      id: vars
-      run: echo ::set-output name=tag::${GITHUB_REF/refs\/tags\//}
-
-    - name: Set up QEMU
-      uses: docker/setup-qemu-action@v1
+    - uses: docker/setup-qemu-action@v1
       with:
-        platforms: ${{ env.PLATFORMS }}
+        platforms: ${{ matrix.platforms }}
 
-    - 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: Set up Docker Buildx
-      id: buildx
-      uses: docker/setup-buildx-action@v1
-      with:
-        version: latest
-       
+    - uses: docker/setup-buildx-action@v1
 
     - uses: docker/build-push-action@v2
       with:
         context: .
-        file: ./deploy/Dockerfile_slim
-        platforms: linux/amd64,linux/arm64,linux/s390x,linux/ppc64le
-        tags: |
-          gcr.io/kaniko-project/executor:${{ env.GITHUB_SHA }}-slim
-
-  build-debug:
-    env:
-      GITHUB_SHA: ${{ github.sha }}
-      GITHUB_REF: ${{ github.ref }}
-      PLATFORMS: "linux/amd64,linux/arm64"
-    runs-on: ubuntu-latest
-    steps:
-    - name: Clone source code
-      uses: actions/checkout@v2
-
-    - name: Get the tags
-      id: vars
-      run: echo ::set-output name=tag::${GITHUB_REF/refs\/tags\//}
-
-    - name: Set up QEMU
-      uses: docker/setup-qemu-action@v1
-      with:
-        platforms: ${{ env.PLATFORMS }}
-
-    - name: Cache Docker layers
-      uses: actions/cache@v2
-      with:
-        path: /tmp/.buildx-cache
-        key: ${{ runner.os }}-buildx-${{ github.sha }}
-        restore-keys: |
-          ${{ runner.os }}-buildx-
-    - name: Set up Docker Buildx
-      id: buildx
-      uses: docker/setup-buildx-action@v1
-      with:
-        version: latest
-       
-
-    - uses: docker/build-push-action@v2
-      with:
-        context: .
-        file:  ./deploy/Dockerfile_debug
-        platforms: linux/amd64,linux/arm64
-        tags: |
-          gcr.io/kaniko-project/executor:${{ env.GITHUB_SHA }}-debug
-
-  build-warmer:
-    env:
-      GITHUB_SHA: ${{ github.sha }}
-      GITHUB_REF: ${{ github.ref }}
-      PLATFORMS: "linux/amd64,linux/arm64"
-    runs-on: ubuntu-latest
-    steps:
-    - name: Clone source code
-      uses: actions/checkout@v2
-
-    - name: Get the tags
-      id: vars
-      run: echo ::set-output name=tag::${GITHUB_REF/refs\/tags\//}
-
-    - name: Set up QEMU
-      uses: docker/setup-qemu-action@v1
-      with:
-        platforms: ${{ env.PLATFORMS }}
-
-    - name: Cache Docker layers
-      uses: actions/cache@v2
-      with:
-        path: /tmp/.buildx-cache
-        key: ${{ runner.os }}-buildx-${{ github.sha }}
-        restore-keys: |
-          ${{ runner.os }}-buildx-
-    - name: Set up Docker Buildx
-      id: buildx
-      uses: docker/setup-buildx-action@v1
-      with:
-        version: latest
-       
-    - uses: docker/build-push-action@v2
-      with:
-        context: .
-        file: ./deploy/Dockerfile_warmer
-        platforms: linux/amd64,linux/arm64
-        tags: |
-          gcr.io/kaniko-project/warmer:${{ env.GITHUB_SHA }}
-
-  build-executor:
-    env:
-      GITHUB_SHA: ${{ github.sha }}
-      GITHUB_REF: ${{ github.ref }}
-      PLATFORMS: "linux/amd64,linux/arm64"
-    runs-on: ubuntu-latest
-    steps:
-    - name: Clone source code
-      uses: actions/checkout@v2
-
-    - name: Get the tags
-      id: vars
-      run: echo ::set-output name=tag::${GITHUB_REF/refs\/tags\//}
-
-    - name: Set up QEMU
-      uses: docker/setup-qemu-action@v1
-      with:
-        platforms: ${{ env.PLATFORMS }}
-
-    - name: Cache Docker layers
-      uses: actions/cache@v2
-      with:
-        path: /tmp/.buildx-cache
-        key: ${{ runner.os }}-buildx-${{ github.sha }}
-        restore-keys: |
-          ${{ runner.os }}-buildx-
-    - name: Set up Docker Buildx
-      id: buildx
-      uses: docker/setup-buildx-action@v1
-      with:
-        version: latest
-
-    - uses: docker/build-push-action@v2
-      with:
-        context: .
-        file: ./deploy/Dockerfile
-        platforms: linux/amd64,linux/arm64
-        tags: |
-          gcr.io/kaniko-project/executor:${{ env.GITHUB_SHA }}
+        file: ${{ matrix.dockerfile }}
+        platforms: ${{ matrix.platforms }}
+        tags: ${{ matrix.name }}
+        # https://github.com/docker/build-push-action/blob/master/docs/advanced/cache.md#github-cache
+        cache-from: type=gha
+        cache-to: type=gha,mode=max