DevContainer Configuration

zer0-mistakes ships a .devcontainer/devcontainer.json that lets you open a fully configured Jekyll development environment with a single click — no local Ruby, Bundler, or Node installation required.

Supported Environments

Configuration File

.devcontainer/devcontainer.json

What’s Pre-Installed

Instead of pulling a generic base image and installing gems on every launch, the devcontainer builds from the repo’s own docker/Dockerfile (the dev-test stage). That stage runs bundle install at image-build time, so the whole Jekyll toolchain is preloaded into the image — the gems always match the checked-out branch’s Gemfile.lock, and there’s no slow bundle install on first boot.

Docker-in-Docker and a standalone Node install are intentionally not included — they aren’t needed to render the site (Playwright/Sass run on the host), and dropping them keeps Codespace creation and prebuilds fast.

Near-instant launch with prebuilds

Because the image is self-contained, GitHub Codespaces prebuilds can build it ahead of time so new Codespaces restore from a ready image in seconds. Enable it under Settings → Codespaces → Set up prebuild (target main, trigger On configuration change). See .devcontainer/README.md.

Post-Create Hook

git config --global --add safe.directory ${containerWorkspaceFolder} && (bundle check || bundle install --jobs 4 --retry 3)

bundle check is a fast no-op when the gems are already baked into the image; it only falls back to a full install if the lockfile drifted.

Post-Start Hook

bundle exec jekyll serve \
  --config '_config.yml,_config_dev.yml' \
  --host 0.0.0.0 --port 4000 --livereload --force_polling

The Jekyll dev server starts automatically every time the container starts (nohup keeps it alive after the hook returns; --force_polling makes file watching reliable over the Codespaces bind mount; logs land in /tmp/jekyll-serve.log). The site is available at http://localhost:4000 and forwarded automatically in VS Code and Codespaces.

Forwarded Ports

VS Code Extensions

The configuration recommends these extensions:

• sissel.shopify-liquid — Liquid template syntax highlighting
• yzhang.markdown-all-in-one — Markdown editing
• DavidAnson.vscode-markdownlint — Markdown linting
• streetsidesoftware.code-spell-checker — Spell check
• esbenp.prettier-vscode — Code formatting
• ms-azuretools.vscode-docker — Docker management

Using the DevContainer Locally

If you have Docker Desktop installed, you can use the devcontainer without Codespaces:

1. Install the VS Code Dev Containers extension
2. Open the repo folder in VS Code
3. Click the notification to Reopen in Container (or use the Command Palette → Dev Containers: Reopen in Container)
4. Wait for the container to build (~2–3 minutes on first run)
5. The site starts automatically at port 4000

Relationship to Docker Compose

The devcontainer and docker-compose.yml serve different purposes:

You can use either (or both) depending on your workflow.

Related

• Docker Development
• Quick Start Guide
• Local Docker Publishing

See also

• [[Development]]
• [[Docker]]
• [[Getting Started]]