Install Docker on Alpine in Proxmox

Installing Docker in an Alpine Linux container on Proxmox is really as simple as running a few commands.

Important notice: Installing Docker in a Proxmox Container is discouraged by the developers. Always backup your container before installing or upgrading Docker, or before upgrading your Proxmox kernel. From time to time, upgrades will break Docker.

Why run Docker on Alpine Linux?

Compared to Debian or Ubuntu container images, Alpine Linux uses one-tenth the space and 60% less RAM. It has minimal packages installed by default which minimizes the attack surface. That makes Alpine an ideal OS for both a Docker host and simple containers.

Installation instructions

Firstly, you'll want to update the packages and upgrade your system. To do so, run:

apk update
apk upgrade

After that, to install Docker in your Alpine Linux container, run the follow command:

apk add docker docker-compose

Next, you'll start the Docker service, run:

service docker start

The output will have some errors, but that's just a consequence of running in an unprivileged container and isn't anything to worry about.

 * Caching service dependencies ... [ ok ]
mount: mounting cgroup2 on /sys/fs/cgroup failed: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: write error: Resource busy
sh: error setting limit: Operation not permitted
 * docker: unable to apply RC_ULIMIT settings
sh: error setting limit: Operation not permitted
 * docker: unable to apply RC_ULIMIT settings
 * /var/log/docker.log: creating file
 * /var/log/docker.log: correcting owner
 * Starting Docker Daemon ... [ ok ]

The Docker service will not run on boot by default. To start the service at boot, run:

rc-update add docker boot

It should output:

 * service docker added to runlevel boot

To allow a regular user access to Docker without doas, add them to the docker group using the follow command:

addgroup $USER docker

Finally, launch a test container to verify everything is working:

docker run hello-world

That will download and launch a simple container with some basic information, after which the container will stop.

Final thoughts

You're now ready to start using Docker in your Alpine Linux container. Consider installing an SSH server and set a timezone.