Docker in dev containers

Recently, I needed to use docker in a dev container for testing the docker build of SearXNG. I was surprised to find that the Docker CLI was not running in the dev container. I had to do some digging to figure out how to get it running.

You can enable docker by adding the following to your devcontainer.json:

{
  "features": {
    "ghcr.io/devcontainers/features/docker-in-docker": {}
  }
}

This will use docker-in-docker from devcontainer/features. It will run another docker daemon from within the dev container. This means any child containers are completely independent of the host.

Alternatively, you can use docker-outside-of-docker which will use the host’s docker daemon, which will probably increase performance a little but potentially could have some security implications.

Now, rebuild your dev container and you should be able to run docker commands inside it.