Using podman instead of docker on Windows Subsystem for Linux (WSL 2)

July 12, 2020 · Updated February 08, 2022

Categories: Windows

Using podman instead of docker on Windows Subsystem for Linux (WSL 2)

With Windows Subsystem for Linux (WSL) version 2, running Linux containers is possible and easy. However, Docker does not work without the docker daemon running, systemd is usually used to govern this, and WSL typically does not have systemd running.

Enter podman.

Podman is a drop-in replacement for the docker commandline tool. It is “daemonless” (in other words, does not require systemd or other service to run in the background), and is backed by Redhat. Podman also works well without root—in other words, containers can easily run in userspace.

Note that it is possible to run the docker daemon without systemd and on pretty much any WSL distribution, even without Docker Desktop. I documented my working setup in a separate article. But I still favor podman for reasons noted in this article.

I use Fedora (you may read more about how I installed Fedora on WSL). In my setup, I needed some minor configuration in order for podman to work properly, and to run rootless. Here are the steps I used.

Installing podman

To install podman, follow the official instructions. Most likely, guidance for your distro should be included there.

A quick summary:

Fedora: sudo dnf install podman
Centos: sudo yum --enablerepo=extras install podman
Debian 11 (bullseye) or later, or sid/unstable: sudo apt install podman
ArchLinux: sudo pacman -S podman and then tweaks for rootless
Debian 10: see the guide for how to set up apt to use the Kubic repos then make sure to run sudo apt update then sudo apt install podman

Set up $XDG_RUNTIME_DIR

Without systemd, the $XDG_RUNTIME_DIR was not available for podman to use for temporary files. I added the following to my ~/.bashrc file:

if [[ -z "$XDG_RUNTIME_DIR" ]]; then
  export XDG_RUNTIME_DIR=/run/user/$UID
  if [[ ! -d "$XDG_RUNTIME_DIR" ]]; then
    export XDG_RUNTIME_DIR=/tmp/$USER-runtime
    if [[ ! -d "$XDG_RUNTIME_DIR" ]]; then
      mkdir -m 0700 "$XDG_RUNTIME_DIR"
    fi
  fi
fi

This script checks if the $XDG_RUNTIME_DIR is set, and, if not, sets it to the default systemd location (/run/user/$UID). If that does not exist, then set and create a temporary directory for the current user.

(Now source your .bashrc with source ~/.bashrc to update environment variables.)

Use file logging and cgroupfs

Do you have /etc/containers/containers.conf or ~/.config/containers/containers.conf? If so, great. On Fedora, and possibly other distributions, you may first need to copy /usr/share/containers/containers.conf to /etc/containers and/or ~/.config/containers. Once the file exists, edit it, making sure that:

cgroup_manager = "cgroupfs" (not systemd)
events_logger = "file" (not journald)
log_driver = "k8s-file" (not journald)

Issue with shadow-utils on Fedora

On Fedora, I had to reinstall shadow-utils in order to have a properly installed newgidmap and newuidmap:

sudo dnf reinstall shadow-utils

Test and prosper

The following should give you a simple command prompt:

$ podman run -it docker.io/library/alpine:latest
Trying to pull docker.io/library/alpine:latest...
Getting image source signatures
Copying blob df20fa9351a1 done
Copying config a24bb40132 done
Writing manifest to image destination
Storing signatures
/ #

Enjoy!

References: