Currently, using a rootless Docker on Arch can reasonable be divided into two approaches: stability and performance. With the stability, the choice is a LTS kernel and a fuse-overlayfs storage driver, while under performance a latest stable kernel is used alongside the latest widely adopted overlay2 storage driver. Lets see how to set-up both options.

Stability with LTS kernel and FUSE

Some distributions, namely Contabo, offer quite a nice Arch image for a VPS. It comes with the linux-lts, which is a sensible choice for a server setup. At the time of writing the latest LTS kernel version was 5.10, however the support for a overlay2 landed in a 5.11, meaning no support for this storage driver with an official LTS kernel. This leaves us with a more time-proven, but possibly less performant fuse-overlayfs storage driver.

yay -S fuse-overlayfs docker-rootless-extras-bin

The above will also pull rootlesskit or rootlesskit-bin into your system. Now the only thing needed is to follow the Arch wiki, in short:

echo "$USER:165536:65536" | sudo tee /etc/subgid /etc/subgid
systemctl --user enable --now docker.socket
echo "export DOCKER_HOST=unix://\$XDG_RUNTIME_DIR/docker.sock" >> .profile

Confirm with docker info and look for a Storage driver.

Performance with stable kernel and overlay2

This is the variation of the above. First we need to switch the latest stable linux kernel, at the time of writing a 5.15 branch, for instance like this:

sudo pacman -S linux
sudo pacman -Rnc linux-lts
sudo mkinitcpio -p linux
sudo grub-mkconfig -o /boot/grub/grub.cfg

For the rest, follow the above, only omitting the installation of fuse-overlayfs. Note that it won't hurt to install it however, as with a given stable kernel, Docker rootless will choose overlay2 automatically.

Overriding the choice

Docker chooses the best available driver, but the choice can be overridden by editing ~/.config/docker/daemon.json with the following:

  "storage-driver": "overlay2"

The above requires at least kernel 5.11 for a rootless Docker to work, as was already stated. Or, alternatively, with a stable kernel and a fuse-overlayfs package present, the FUSE storage driver can be forced with:

  "storage-driver": "fuse-overlayfs"

Now rerun the services:

systemctl --user stop docker.service
systemctl --user stop docker.socket
systemctl --user enable docker.socket --now
docker info

Note: Although guides prefer to mention a socket for a docker Rootless, consider enabling docker.service instead of docker.socket for critical services that should run all the time.

However, on my machine this led to an error similar to this one

Error starting daemon: error initializing graphdriver: "/home/peterbabic/.local/share/docker" contains other graph drivers:
fuse-overlayfs; Please cleanup or explicitly choose storage driver (-s <DRIVER>)

The error can be found in the journal under the following:

ournalctl --user -xeu docker.service

Warning: the next step might lead to a loss of data! Please proceed with caution and with a proper backups.

In case you are just setting things up, the safest way is just to remove all the Docker rootless data:

rm -rf ~/.local/share/docker

Now rerun the service, described in the previous step. The chosen driver should be used.