I've been having fun playing with GitHub codespaces. One of the things that has seemed odd to me is the language-specific development environments. Most projects—even small side projects—have multiple languages. Composing these images feels messy. I've always enjoyed asdf for managing language versions in a unified fashion.

This project builds a devcontainer image (for use with GitHub Codespace) setup with asdf support. It also includes a nice utility script for installing all asdf plugins, finding all .tool-versions files, installing the versions specified, and starting up a docker-compose.yml if one exists.

Here's my blog post which walks through this in detail.

Main design goals:

• Include all relevant packages that most popular languages require for install. The Dockerfile is very aggressive with including many packages so the container can install asdf packages in many languages. I am no sysadmin so there may be negative side effects with this approach.
• Fix homebrew not working due to out of date image. This means apt-get update in the build, combined with a monthly gh actions cron, fixes this.
• Easily install all asdf plugins used in a project. /asdf-post-create.sh finds all .tool-versions included in the repo and installs the relevant asdf plugins.
• Easily start docker-compose services. For instance, if your project requires postgres + redis, you can include a docker-compose.yml file in .devcontainer/ and it will be started when you run /asdf-post-create.sh.

Here are the languages I've confirmed compile and run via asdf on this image:

• Elixir + Erlang
• Python
• Ruby
• NodeJS
• Deno
• Bun
• PHP

Check out devcontainer-example folder for how to use this in your application.

Here's how to easily copy the example into your project:

mkdir .devcontainer && cd .devcontainer && curl https://codeload.github.com/iloveitaly/asdf-devcontainer/tar.gz/main | tar -xz --strip=2 asdf-devcontainer-main/devcontainer-example

If you clone the repo locally, here's a quick script to copy:

cp -R ~/Projects/asdf-devcontainer/devcontainer-example your-new-project/.devcontainer

Here's what your devcontainer.json should look like:

{
	"image": "iloveitaly/asdf-devcontainer:0-ubuntu-22.04",
	"postCreateCommand": "/asdf-post-create.sh && bin/setup",
	"remoteUser": "vscode",
	"features": {
		"homebrew": "latest",
		"ghcr.io/devcontainers/features/sshd:1": {
			"version": "latest"
		},
		"ghcr.io/devcontainers/features/docker-in-docker:1": {
			"version": "latest",
			"dockerDashComposeVersion":"v2"
		}
	}
}

Easiest way to iterate on this image is to setup a codespace and rebuild the Dockerfile. Some tips:

• What base variants exist? http https://mcr.microsoft.com/v2/vscode/devcontainers/base/tags/list | fzf
• Build on a different base variant docker build -t asdf-devcontainer . --build-arg VARIANT=dev-ubuntu
• Run a shell inside the image docker run --rm -it asdf-devcontainer bash -lc
• Get github webhook structure for github actions development gh api repos/iloveitaly/asdf-devcontainer/events
• View all available devcontainer features
• Devcontainers open source spec