Merge pull request #5945 from dokku/faster-ci

tests: split out image building into it's own job to speed up ci

.github/workflows/ci.yml

@@ -61,6 +61,8 @@ jobs:
 
       - name: build package
         run: ./tests/ci/setup.sh build
+        env:
+          SKIP_IMAGE_BUILD: true
 
       - name: set matrix for build
         id: set-matrix
@@ -75,6 +77,42 @@ jobs:
           name: build
           path: build
 
+  build-image:
+    name: build-image.${{ matrix.architecture }}
+    needs: build
+    runs-on: ubuntu-20.04
+    strategy:
+      fail-fast: false
+      matrix:
+        architecture:
+          - linux/amd64
+          - linux/arm
+          - linux/arm64
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: download packages
+        uses: actions/download-artifact@v3
+        with:
+          name: build
+          path: build
+
+      - name: set up qemu
+        uses: docker/setup-qemu-action@v2
+
+      - name: set up docker buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: build docker image
+        run: |
+          docker buildx build \
+                --platform ${{ matrix.architecture }} \
+                --progress plain \
+                --tag "dokku/dokku:latest" \
+                .
+
   unit-tests:
     name: unit.${{ matrix.index }}
     needs: build

contrib/release-dokku

@@ -391,7 +391,7 @@ fn-build-docker-image() {
       --push \
       --tag "dokku/dokku:latest" \
       --tag "dokku/dokku:$VERSION" .
-  else
+  elif [[ "$SKIP_IMAGE_BUILD" != "true" ]]; then
     docker buildx build \
       --platform linux/arm,linux/arm64,linux/amd64 \
       --progress plain \