Add Dockerfile and create image action

Author: vox-humana

.github/workflows/docker.yml

@@ -0,0 +1,54 @@
+name: Create and publish a Docker image
+
+on:
+  push:
+    tags:
+      - "*"
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push-image:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ github.event.inputs.ref }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v4
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+        with:
+          platforms: arm64
+
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@v2
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v3
+        with:
+          context: .
+          platforms: linux/amd64, linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

Dockerfile

@@ -0,0 +1,15 @@
+# syntax=docker/dockerfile:1
+
+# Swift official image with arm64 support
+# https://hub.docker.com/r/arm64v8/swift/
+ARG SWIFT_IMAGE=swift:focal
+
+FROM $SWIFT_IMAGE AS builder
+COPY . /workspace
+WORKDIR /workspace
+RUN swift build -c release && mv `swift build -c release --show-bin-path`/swiftformat /workspace
+
+FROM $SWIFT_IMAGE-slim AS runner
+COPY --from=builder /workspace/swiftformat /usr/bin
+ENTRYPOINT [ "swiftformat" ]
+CMD ["."]