feat(github-ci): add docker image build

.github/workflows/docker-image.yml

@@ -0,0 +1,50 @@
+name: Build docker image
+
+on:
+  push:
+    tags:
+      - '*'
+
+env:
+  PROJECT_NAME: UnityNuGet
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-image:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker 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: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v4
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          push: true
+          platforms: linux/amd64,linux/arm64
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

Dockerfile

@@ -1,4 +1,5 @@
-FROM mcr.microsoft.com/dotnet/sdk:7.0.100 AS build
+FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:7.0 AS build
+ARG TARGETARCH
 WORKDIR /app
 
 RUN mkdir -p src/UnityNuGet && mkdir -p src/UnityNuGet.Server && mkdir -p src/UnityNuGet.Tests
@@ -7,10 +8,10 @@ COPY src/*.sln src
 COPY src/UnityNuGet/*.csproj src/UnityNuGet
 COPY src/UnityNuGet.Server/*.csproj src/UnityNuGet.Server
 COPY src/UnityNuGet.Tests/*.csproj src/UnityNuGet.Tests
-RUN dotnet restore src
+RUN dotnet restore src -a $TARGETARCH
 
 COPY . ./
-RUN dotnet publish src -c Release -o /app/src/out
+RUN dotnet publish src -a $TARGETARCH -c Release -o /app/src/out
 
 # Build runtime image
 FROM mcr.microsoft.com/dotnet/aspnet:7.0