Ubuntu Docker-in-Docker Image

Docker-in-Docker is a docker solution mostly used on CI/CD pipelines. This dind image is based on Ubuntu and features the s6-overlay for running the dockerd service. s6-overlay can come in handy when creating multi service agents for CI/CD pipelines. For example, Azure Devops Pipelines agent.

Tags

• 22.04, latest
• 20.04
• 18.04

Usage

As Base Image

You can and should use it as a base image. It is as simple as adding your own CMD. However, you may want to checkout the conventions and limits of s6-overlay. Note that, s6-overlay uses ENTRYPOINT, so consider your use cases before using this image.

Running the Image

docker run -it --privileged dcagatay/ubuntu-dind:20.04 /bin/bash

You probably won't but you can run the image with the above command.

Environment Variables

• DOCKER_EXTRA_OPTS: Used to give arguments to dockerd command. Details can be found on its reference. Default: --log-level=error --experimental

Build

You can build your own images specifying following build arguments.

• DOCKER_VERSION: Docker version to be installed.
• DOCKER_CHANNEL: Docker release channel. Can be one of stable, test, nightly. Default: stable
• DOCKER_COMPOSE_VERSION: Version of the docker-compose.

Credits

I was inspired by cruizba/ubuntu-dind. It uses a supervisord to run the dockerd as a service whereas this image uses the s6-overlay.

WARNING

The --privileged argument has security implications.