release: build docs as container image

.github/workflows/build.yml

@@ -4,6 +4,9 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  IMAGE_NAME: "docs/docker-docs"
+
 on:
   push:
     # needs push event on default branch otherwise cache is evicted when pull request is merged
@@ -113,3 +116,41 @@ jobs:
             *.cache-to=type=gha,scope=validate-${{ matrix.target }},mode=max
             *.cache-from=type=gha,scope=validate-${{ matrix.target }}
             *.cache-from=type=gha,scope=build
+
+  image:
+    runs-on: ubuntu-24.04
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      -
+        name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.IMAGE_NAME }}
+      -
+        if: ${{ github.event_name != 'pull_request' }}
+        name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKER_USER }}
+          password: ${{ secrets.DOCKER_TOKEN }}
+      -
+        name: Build website image
+        uses: docker/bake-action@v5
+        with:
+          files: |
+            docker-bake.hcl
+            ${{ steps.meta.outputs.bake-file-tags }}
+            ${{ steps.meta.outputs.bake-file-annotations }}
+          targets: image
+          set: |
+            *.cache-from=type=gha,scope=deploy-${{ env.BRANCH_NAME }}
+            *.cache-to=type=gha,scope=deploy-${{ env.BRANCH_NAME }},mode=max
+          push: ${{ github.event_name != 'pull_request' }}

Dockerfile

@@ -7,6 +7,7 @@ ARG HTMLTEST_VERSION=0.17.0
 ARG HUGO_VERSION=0.141.0
 ARG NODE_VERSION=22
 ARG PAGEFIND_VERSION=1.3.0
+ARG NGINX_VERSION=1.27
 
 # base defines the generic base stage
 FROM golang:${GO_VERSION}-alpine${ALPINE_VERSION} AS base
@@ -149,3 +150,7 @@ EOT
 FROM scratch AS release
 COPY --from=build /project/public /
 COPY --from=pagefind /pagefind /pagefind
+
+# image creates a Docker image for the documentation site
+FROM nginx:${NGINX_VERSION}-alpine AS image
+COPY --from=release / /usr/share/nginx/html

docker-bake.hcl

@@ -35,6 +35,19 @@ target "release" {
   provenance = false
 }
 
+target "image" {
+  args = {
+    HUGO_ENV = HUGO_ENV
+    DOCS_URL = "/"
+  }
+  target = "image"
+  attest = [
+    "type=provenance,mode=max",
+    "type=sbom",
+  ]
+  output = ["type=docker"]
+}
+
 group "validate" {
   targets = ["lint", "test", "unused-media", "test-go-redirects", "dockerfile-lint", "path-warnings"]
 }