ci: Build multi-platform image with cross-compilation

The previous build workflow used emulation to build the Docker image,
which results in a somewhat complicated push-by-digest and merge
workflow to create a multi-platform image.

This commit changes the Docker build to use cross-compilation instead,
resulting in a faster and more straightforward build.

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

.github/workflows/image.yml

@@ -3,6 +3,7 @@ name: Build Docker image
 on:
   release:
     types: [published]
+  pull_request:
 permissions:
   packages: write
 
@@ -12,18 +13,8 @@ env:
 jobs:
   build:
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        platform:
-          - linux/amd64
-          - linux/arm64
-    steps:
-      - name: Prepare
-        run: |
-          platform=${{ matrix.platform }}
-          echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
 
+    steps:
       - name: Checkout
         uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
 
@@ -33,9 +24,6 @@ jobs:
         with:
           images: ${{ env.REGISTRY_IMAGE }}
 
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@49b3bc8e6bdd4a60e6116a5414239cba5943d3cf # v3.2.0
-
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db # v3.6.1
 
@@ -47,69 +35,14 @@ jobs:
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - name: Build and push by digest
+      - name: Build and push
         id: build
         uses: docker/build-push-action@16ebe778df0e7752d2cfcbd924afdbbd89c1a755 # v6.6.1
         with:
           context: .
-          push: ${{ startsWith(github.ref, 'refs/tags') }}
-          platforms: ${{ matrix.platform }}
+          provenance: mode=max
+          sbom: true
+          push: ${{ github.event_name != 'pull_request' }}
+          platforms: linux/amd64,linux/arm64
+          tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-          outputs: type=image,name=${{ env.REGISTRY_IMAGE }},push-by-digest=true,name-canonical=true,push=true
-
-      - name: Export digest
-        run: |
-          mkdir -p /tmp/digests
-          digest="${{ steps.build.outputs.digest }}"
-          touch "/tmp/digests/${digest#sha256:}"
-
-      - name: Upload digest
-        uses: actions/upload-artifact@834a144ee995460fba8ed112a2fc961b36a5ec5a # v4.3.6
-        with:
-          name: digests-${{ env.PLATFORM_PAIR }}
-          path: /tmp/digests/*
-          if-no-files-found: error
-          retention-days: 1
-
-  merge:
-    runs-on: ubuntu-latest
-    needs:
-      - build
-    steps:
-      - name: Download digests
-        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
-        with:
-          path: /tmp/digests
-          pattern: digests-*
-          merge-multiple: true
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db # v3.6.1
-
-      - name: Docker meta
-        id: meta
-        uses: docker/metadata-action@8e5442c4ef9f78752691e2d8f8d19755c6f78e81 # v5.5.1
-        with:
-          images: ${{ env.REGISTRY_IMAGE }}
-
-          flavor: |
-            latest=false
-
-      - name: Login to GHCR
-        uses: docker/login-action@9780b0c442fbb1117ed29e0efdff1e18412f7567 # v3.3.0
-        with:
-          registry: ghcr.io
-          username: ${{ github.repository_owner }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-
-      - name: Create manifest list and push
-        if: ${{ startsWith(github.ref, 'refs/tags') }}
-        working-directory: /tmp/digests
-        run: |
-          docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
-            $(printf '${{ env.REGISTRY_IMAGE }}@sha256:%s ' *)
-
-      - name: Inspect image
-        if: ${{ startsWith(github.ref, 'refs/tags') }}
-        run: |
-          docker buildx imagetools inspect ${{ env.REGISTRY_IMAGE }}:${{ steps.meta.outputs.version }}

Dockerfile

@@ -2,11 +2,17 @@
 # Twitter:      https://twitter.com/gohugoio
 # Website:      https://gohugo.io/
 
-FROM golang:1.22.6-alpine AS build
+FROM --platform=$BUILDPLATFORM tonistiigi/xx:1.5.0 AS xx
+
+FROM --platform=$BUILDPLATFORM golang:1.22.6-alpine AS build
+
+# Set up cross-compilation helpers
+COPY --from=xx / /
+RUN apk add clang lld
 
 # Optionally set HUGO_BUILD_TAGS to "extended" or "nodeploy" when building like so:
 #   docker build --build-arg HUGO_BUILD_TAGS=extended .
-ARG HUGO_BUILD_TAGS
+ARG HUGO_BUILD_TAGS="none"
 
 ARG CGO=1
 ENV CGO_ENABLED=${CGO}
@@ -15,20 +21,26 @@ ENV GO111MODULE=on
 
 WORKDIR /go/src/github.com/gohugoio/hugo
 
-COPY . /go/src/github.com/gohugoio/hugo/
+RUN --mount=src=go.mod,target=go.mod \
+    --mount=src=go.sum,target=go.sum \
+    --mount=type=cache,target=/go/pkg/mod \
+    go mod download
 
+ARG TARGETPLATFORM
 # gcc/g++ are required to build SASS libraries for extended version
-RUN apk update && \
-    apk add --no-cache gcc g++ musl-dev git && \
-    go install github.com/magefile/mage
-
-RUN mage hugo && mage install
+RUN xx-apk add --no-scripts --no-cache gcc g++ musl-dev git
+RUN --mount=target=. \
+    --mount=type=cache,target=/go/pkg/mod <<EOT
+    set -ex
+    xx-go build -tags "$HUGO_BUILD_TAGS" -o /usr/bin/hugo
+    xx-verify /usr/bin/hugo
+EOT
 
 # ---
 
 FROM alpine:3.18
 
-COPY --from=build /go/bin/hugo /usr/bin/hugo
+COPY --from=build /usr/bin/hugo /usr/bin/hugo
 
 # libc6-compat & libstdc++ are required for extended SASS libraries
 # ca-certificates are required to fetch outside resources (like Twitter oEmbeds)