release: build docs as container image

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

.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
@@ -98,3 +101,39 @@ jobs:
           set: |
             *.cache-from=type=gha,scope=releaser
             *.cache-to=type=gha,scope=releaser,mode=max
+
+  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@8e5442c4ef9f78752691e2d8f8d19755c6f78e81 # v5.5.1
+        with:
+          images: ${{ env.IMAGE_NAME }}
+      -
+        name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKER_USER }}
+          password: ${{ secrets.DOCKER_TOKEN }}
+      -
+        name: Build website image
+        uses: docker/bake-action@v5
+        with:
+          files: |
+            docker-bake.hcl
+            ${{ steps.meta.outputs.bake-file }}
+          targets: image
+          set: |
+            *.cache-from=type=gha,scope=deploy-${{ 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 ALPINE_VERSION=3.20
 ARG GO_VERSION=1.23
 # HTML_TEST_VERSION sets the wjdp/htmltest version for HTML testing
 ARG HTMLTEST_VERSION=0.17.0
+ARG NGINX_VERSION=1.27
 
 # base is the base stage with build dependencies
 FROM golang:${GO_VERSION}-alpine AS base
@@ -39,9 +40,9 @@ FROM build-base AS dev
 # build creates production builds with Hugo
 FROM build-base AS build
 # HUGO_ENV sets the hugo.Environment (production, development, preview)
-ARG HUGO_ENV
+ARG HUGO_ENV="development"
 # DOCS_URL sets the base URL for the site
-ARG DOCS_URL
+ARG DOCS_URL="https://docs.docker.com"
 RUN hugo --gc --minify -d /out -e $HUGO_ENV -b $DOCS_URL
 
 # lint lints markdown files
@@ -146,3 +147,7 @@ EOT
 FROM scratch AS release
 COPY --from=build /out /
 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

@@ -1,9 +1,9 @@
 variable "HUGO_ENV" {
-  default = "development"
+  default = null
 }
 
 variable "DOCS_URL" {
-  default = "https://docs.docker.com"
+  default = null
 }
 
 variable "DOCS_SITE_DIR" {
@@ -31,6 +31,19 @@ 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"]
 }