Podman

The following table shows the feature implementation status of Rootless Podman:

Version Notable changes
Pre-1.1 Initial support for Rootless mode
1.1 Added support for port forwarding (podman run -p)
1.5 Added support for cgroup v2
2.1 Added support for multi-container networking (podman create network)

FAQ: Docker/Moby vs Podman?

Until recently, Docker/Moby had lacked support for cgroup v2, and on the other hand Podman had lacked support for multi-container networking.

As of October 2020, the two projects implement almost the same features with regard to the support for Rootless mode.

Installation

Note

Please read the common steps first.

The easiest way to install Rootless Podman is to install podman package. Requires sudo.

See here
$ sudo dnf install -y podman

Rootless Podman could also be installed without sudo in theory. However, as of October 2020, there is no official Podman binaries that can be installed without sudo.

Usage

Just run podman command.

$ podman run docker.io/library/hello-world

Tips

Enabling resource limitations (podman run --cpus, podman run --memory, …)

Resource-related flags of podman run, such as --cpus, --memory, --blkio-weight, and --pids-limit can be used only when the following conditions are satisfied:

  • Podman version is 1.5 later
  • runc version is 1.0-rc91 or later, or crun is installed
  • The host is running with cgroup v2
  • The host is running with systemd

To impose resource limitations without cgroup, see https://docs.docker.com/engine/security/rootless/#limiting-resources (read docker as podman)

Changing the port forwarder

Podman uses RootlessKit as the default port forwarder.

However, as explained in How it works, sometimes slirp4netns port forwarder is preferred over RootlessKit port forwarder.

To change the port forwarder to slirp4netns, run podman run with --network slirp4netns:port_handler=slirp4netns.

See also http://docs.podman.io/en/latest/markdown/podman-run.1.html

Starting containers on boot

As Podman lacks the central daemon, you need to create systemd unit files to launch the each of the containers on the system startup.

See http://docs.podman.io/en/latest/markdown/podman-generate-systemd.1.html

Also, you need to run sudo loginctl enable-linger .... See Getting Started/Login.

Resetting to factory settings

Run the following commands to remove all containers and configurations:

$ podman rm -f $(podman ps -a -q)
$ podman unshare rm -rf ~/.local/share/containers ~/.config/containers

To uninstall binaries, remove podman package with the package manager.

Further information

See https://github.com/containers/podman/blob/master/docs/tutorials/rootless_tutorial.md