Enhance Docker workflow: add Buildx setup and update README with Docker Compose instructions

.forgejo/workflows/publish-container.yml

@@ -65,6 +65,27 @@ jobs:
           echo "${HOME}/.local/bin" >> "${GITHUB_PATH}"
           "${HOME}/.local/bin/docker" --version
 
+      - name: Ensure Docker Buildx exists
+        run: |
+          set -eu
+          if docker buildx version >/dev/null 2>&1; then
+            docker buildx version
+            exit 0
+          fi
+
+          ARCH="$(uname -m)"
+          case "${ARCH}" in
+            x86_64) BUILDX_ARCH="amd64" ;;
+            aarch64|arm64) BUILDX_ARCH="arm64" ;;
+            *) echo "Unsupported architecture for Docker Buildx bootstrap: ${ARCH}"; exit 1 ;;
+          esac
+
+          BUILDX_VERSION="v0.21.1"
+          mkdir -p "${HOME}/.docker/cli-plugins"
+          curl -fsSL "https://github.com/docker/buildx/releases/download/${BUILDX_VERSION}/buildx-${BUILDX_VERSION}.linux-${BUILDX_ARCH}" -o "${HOME}/.docker/cli-plugins/docker-buildx"
+          chmod +x "${HOME}/.docker/cli-plugins/docker-buildx"
+          docker buildx version
+
       # Simplified: we trust DOCKER_HOST (default to tcp://172.17.0.1:2375). If you
       # need a different endpoint, set the Forgejo variable `DOCKER_HOST`.
 
@@ -75,6 +96,13 @@ jobs:
           docker version
           docker info >/dev/null
 
+      - name: Create Buildx builder
+        run: |
+          set -eu
+          docker buildx rm forgejo-builder >/dev/null 2>&1 || true
+          docker buildx create --name forgejo-builder --driver docker-container --use
+          docker buildx inspect --bootstrap
+
       - name: Restore and publish app
         run: dotnet publish src/MaddoScientisto.Web/MaddoScientisto.Web.csproj -c Release -o ./artifacts/publish
 
@@ -82,17 +110,14 @@ jobs:
         run: |
           echo "${{ secrets.FORGEJO_REGISTRY_TOKEN }}" | docker login "${REGISTRY}" -u "${{ secrets.FORGEJO_REGISTRY_USERNAME }}" --password-stdin
 
-      - name: Build image
+      - name: Build and push image
         run: |
           set -eu
           IMAGE_REF="${REGISTRY}/${IMAGE_NAMESPACE}/${IMAGE_NAME}"
           SHORT_SHA="$(echo "${GITHUB_SHA}" | cut -c1-12)"
-          docker build -t "${IMAGE_REF}:sha-${SHORT_SHA}" -t "${IMAGE_REF}:latest" .
-
-      - name: Push image tags
-        run: |
-          set -eu
-          IMAGE_REF="${REGISTRY}/${IMAGE_NAMESPACE}/${IMAGE_NAME}"
-          SHORT_SHA="$(echo "${GITHUB_SHA}" | cut -c1-12)"
-          docker push "${IMAGE_REF}:sha-${SHORT_SHA}"
-          docker push "${IMAGE_REF}:latest"
+          docker buildx build \
+            --builder forgejo-builder \
+            --tag "${IMAGE_REF}:sha-${SHORT_SHA}" \
+            --tag "${IMAGE_REF}:latest" \
+            --push \
+            .