devcontainers

Development Containers that follow thoughtbot's conventions, covering images and features for both local development (if desired) and GitHub Codespaces.

By building and publishing custom images, we can dramatically speed up the time taken to spin up a new development environment, and keep the project-specific overrides to a minimum.

Dev Containers are Docker images intended for development and testing, formed from a base image along with "features" which provide additional functionality, such as building and installing the most recent release version of Git.

A project has it's own configuration based on this image, with overrides specific to the project (like additional features for functionality not baked into the image being used) and potentially a Docker Compose file for additional services (like PostgreSQL).

Some examples are live and being regularly used, some in this repo are there to demonstrate different configuration approaches that we've seen on projects.

• This repo has a configuration based on our debian base image which can be used to work on the Dev Containers themselves,
• codespaces-demo: shows a simple Rails app running with a Dev Container on GitHub Codespaces (but not these images and features),

• debian is a barebones image without any development environments
  • It's based on images provided by the buildpack-deps project,
  • Images are tagged by date of build, the most recent also tagged as latest,
• universal is a bigger image, inspired by laptop, which should be everything you need for a web project
  • It's based on the most recent build of debian,
  • Images are tagged by date of build, along with a single latest pointed to the most recent

We currently only build amd64 images, as this is enough to work with Codespaces.

These features are intended to be used with our images, but should be compatible with any image.

• asdf: the tool version manager
  • asdf-plugin-nodejs: plugin to support Node.js
  • asdf-plugin-ruby: plugin to support Ruby
• browsers: headless browsers commonly used in tests

Build the image:

$ devcontainer build \
    --image-name ghcr.io/thoughtbot/devcontainers/images/debian \
    --workspace-folder images/debian

This builds an image tagged as latest. This can be tested by starting the container and running the tests:

$ devcontainer up \
    --id-label test-container=debian \
    --workspace-folder "images/debian"
$ devcontainer exec \
    --id-label test-container=debian \
    --workspace-folder images/debian \
    /bin/sh test/test.sh

And published:

$ docker push ghcr.io/thoughtbot/devcontainers/images/debian:latest

We don't need an explicit build step before testing, which can be done with:

$ devcontainer features test \
    --project-folder features \
    --features asdf \
    --base-image ghcr.io/thoughtbot/devcontainers/images/debian

Publishing can be done with:

$ devcontainer features publish features/src/asdf \
    --namespace thoughtbot/devcontainers/features

Depending on the version of the feature, this will publish tags like: 1, 1.0, 1.0.7, latest, if the feature version was "1.0.7".

• The devcontainers CLI doesn't properly support Podman (builds will fail),
• In addition, images need to exist for your current architecture; buildpack-deps isn't currently built for Apple Silicon (arm64), which is partly why this doesn't,
• To pull private packages from GitHub Packages, "inherit access from source repository" should be enabled in package settings,
• To publish packages from GitHub Actions, we also need to enable write access to the package from the repository