Add Docker support

.dockerignore

@@ -0,0 +1,20 @@
+# .git is deliberately not ignored: jekyll-last-modified-at needs the history
+
+_site
+_pages
+.jekyll-cache
+.jekyll-metadata
+vendor
+.bundle
+.netlify
+
+Dockerfile
+compose.yaml
+.env
+.dockerignore
+.github
+.gitignore
+.gitattributes
+
+*.sw?
+*~

.gitignore

@@ -10,3 +10,6 @@ vendor/
 
 # Local Netlify folder
 .netlify
+
+# Host uid/gid for docker compose, see the Makefile
+.env

Dockerfile

@@ -0,0 +1,68 @@
+# syntax=docker/dockerfile:1
+
+# Development image for the docs site.
+#
+# Gemfile.lock only lists x86_64-linux, so build on amd64 or run
+# `bundle lock --add-platform aarch64-linux` first. Not Alpine: the locked
+# sass-embedded, ffi and google-protobuf gems are glibc builds.
+
+ARG RUBY_VERSION=3.4
+ARG DEBIAN_RELEASE=trixie
+
+FROM ruby:${RUBY_VERSION}-slim-${DEBIAN_RELEASE} AS base
+
+ENV LANG=C.UTF-8 \
+    LC_ALL=C.UTF-8 \
+    TZ=UTC \
+    BUNDLE_PATH=/usr/local/bundle \
+    BUNDLE_JOBS=4 \
+    BUNDLE_RETRY=3
+
+# jekyll-last-modified-at reads each file's last commit date
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends git \
+    && rm -rf /var/lib/apt/lists/*
+
+
+FROM base AS gems
+
+# eventmachine and http_parser.rb have no precompiled gems
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends build-essential libssl-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+ENV BUNDLE_FROZEN=true
+
+WORKDIR /app
+COPY Gemfile Gemfile.lock ./
+RUN bundle install && rm -rf "${BUNDLE_PATH}"/cache
+
+
+FROM base AS dev
+
+# Pass --build-arg UID=$(id -u) so generated files match the host owner
+ARG UID=1000
+ARG GID=1000
+
+RUN if ! getent group "${GID}" >/dev/null; then groupadd --gid "${GID}" jekyll; fi \
+    && useradd --uid "${UID}" --gid "${GID}" --create-home --shell /bin/bash jekyll
+
+# git refuses to read a repo it thinks someone else owns
+RUN git config --system --add safe.directory /app
+
+COPY --from=gems --chown=${UID}:${GID} ${BUNDLE_PATH} ${BUNDLE_PATH}
+
+# WORKDIR would create these root-owned, and jekyll writes to all three
+RUN install -d -o "${UID}" -g "${GID}" /app /app/_site /app/.jekyll-cache
+
+WORKDIR /app
+COPY --chown=${UID}:${GID} . .
+
+USER jekyll
+
+# 4000 site, 35729 livereload
+EXPOSE 4000 35729
+
+# Also allows `docker run <image> jekyll build`
+ENTRYPOINT ["bundle", "exec"]
+CMD ["jekyll", "serve", "--host", "0.0.0.0", "--livereload", "--drafts"]

Makefile

@@ -1,6 +1,7 @@
 # Makefile for BleachBit documentation site
 
-.PHONY: help clean serve build install update
+.PHONY: help clean serve build install update \
+	docker-serve docker-build docker-shell docker-down
 
 # Default target
 help:
@@ -11,6 +12,11 @@ help:
 	@echo "  build    - Build the static site"
 	@echo "  install  - Install Ruby dependencies"
 	@echo "  update   - Update Ruby dependencies"
+	@echo ""
+	@echo "  docker-serve - Start the development server in a container"
+	@echo "  docker-build - Build the static site in a container"
+	@echo "  docker-shell - Open a shell in the container"
+	@echo "  docker-down  - Stop the container"
 
 # Clean generated files and dependencies
 clean:
@@ -49,3 +55,26 @@ serve:
 serve-prod:
 	@echo "Starting production-like server..."
 	bundle exec jekyll serve
+
+# Compose reads .env automatically, so the container runs as the host user
+# instead of root. Delete this file if your uid changes.
+.env:
+	@printf 'HOST_UID=%s\nHOST_GID=%s\n' $$(id -u) $$(id -g) > $@
+	@echo "Wrote $@"
+
+# Serve in a container
+docker-serve: .env
+	docker compose up --build
+
+# Build the static site in a container
+docker-build: .env
+	docker compose run --rm --build docs jekyll build
+	@echo "Site built in _site/"
+
+# Shell in the container, for bundle update and friends
+docker-shell: .env
+	docker compose run --rm --build --entrypoint bash docs
+
+# Stop the container
+docker-down:
+	docker compose down

compose.yaml

@@ -0,0 +1,33 @@
+services:
+  docs:
+    build:
+      context: .
+      target: dev
+      args:
+        UID: ${HOST_UID:-1000}
+        GID: ${HOST_GID:-1000}
+    environment:
+      JEKYLL_ENV: development
+    ports:
+      - "127.0.0.1:4000:4000"
+      - "127.0.0.1:35729:35729"
+    volumes:
+      # Append :z under podman or a docker daemon with selinux-enabled. That
+      # relabels this directory to container_file_t on the host.
+      - .:/app
+    # Inherits `jekyll serve` from the image. Docker Desktop on macOS and
+    # Windows needs inotify replaced with polling:
+    # command: [jekyll, serve, --host, 0.0.0.0, --livereload, --drafts, --force_polling]
+    healthcheck:
+      test:
+        [
+          "CMD",
+          "ruby",
+          "-rnet/http",
+          "-e",
+          "exit Net::HTTP.get_response(URI('http://127.0.0.1:4000/')).is_a?(Net::HTTPSuccess) ? 0 : 1",
+        ]
+      interval: 30s
+      timeout: 5s
+      start_period: 60s
+      retries: 3