add docs-serve task for local Jekyll preview via Docker

Add 'task docs-serve' that runs Jekyll in a Docker container so
developers can preview the documentation site without installing
Ruby or Jekyll locally. Uses a _config.dev.yml override to clear
the baseurl for local serving at http://localhost:4000 with
LiveReload enabled.

Assisted-By: docker-agent

Author: dgageot

Taskfile.yml

@@ -86,6 +86,18 @@ tasks:
     desc: Build and Push Docker image
     cmd: docker buildx build --push --platform linux/amd64,linux/arm64 -t docker/docker-agent  {{.BUILD_ARGS}} .
 
+  docs-serve:
+    desc: Preview the Jekyll documentation site locally
+    dir: docs
+    cmd: |
+      docker build -t docker-agent-docs . && \
+      docker run --rm \
+        -v "{{.TASKFILE_DIR}}/docs:/srv/jekyll" \
+        -e JEKYLL_ENV=development \
+        -p 4000:4000 \
+        docker-agent-docs \
+        jekyll serve --host 0.0.0.0 --config _config.yml,_config.dev.yml --livereload
+
   record-demo:
     desc: Record demo gif
     cmd: vhs ./docs/recordings/demo.tape

docs/Dockerfile

@@ -0,0 +1,7 @@
+FROM jekyll/jekyll:4
+
+COPY Gemfile Gemfile.lock* ./
+RUN bundle install
+
+EXPOSE 4000
+CMD ["jekyll", "serve", "--host", "0.0.0.0", "--livereload"]

docs/_config.dev.yml

@@ -0,0 +1,3 @@
+# Override for local development preview
+# Clears the baseurl so pages are served at the root
+baseurl: ""

docs/_config.yml

@@ -36,6 +36,8 @@ exclude:
   - .markdownlint-cli2.yaml
   - .prettierrc
   - .prettierignore
+  - _config.dev.yml
+  - Dockerfile
 
 # Default front matter
 defaults: