My sysadmin notes

Podman cheat sheet

Posted on Apr 20, 2024
Table of contents:

This is a cheat sheet of podman useful information and commands.

Podman is feature equivalent with docker, with the advantage of not requiring root privileges and a daemon running as root. It can be used alongside with buildah to build container images, and skopeo to manage container images in a registry.

Install podman

  • Install the package: apt install podman
  • Allow for unqualified search in the docker.io and quay.io repositories: echo 'unqualified-search-registries=["docker.io", "quay.io"]' > $HOME/.config/containers/registries.conf
  • Enable the auto-update timer: systemctl [--user] enable --now podman-auto-update.timer

Image management

  • List pulled images: podman image ls
  • Show the history of an image: podman image history <image name>
  • Retrieve or update an image: podman image pull <image name> Do not forget to restart the containers using this image to use the updated version.
  • Retrieve a specific image version: podman pull <image name>:<version|latest>

Get information about running containers

  • List running containers: podman ps
  • List all containers: podman ps -a
  • Sort all containers by size: podman ps --size --sort size
  • Sort all containers by creation time: podman ps --sort created
  • List with a customized format: podman ps --all --format "{{.Names}} {{.Ports}} {{.Mounts}} {{.Status}}"
  • Live resource information by container: podman stats

Control a container

  • Create a new container and detach it: podman run -dt <image name>
  • Create a new container and get an interactive shell: podman run -it <image name>
  • Create a new container and map a directory: -v <host directory>:<container mount point>
  • Create a new container and map a network port: -p <host port>:<container port>
  • Enable Auto-update: --label io.containers.autoupdate=registry
  • Checking for updates: podman auto-update
  • Copy a file to a container: podman cp <src> <dest>
  • Get an interactive shell inside a running container: podman exec -it <CONTAINER ID> /bin/bash
  • podman [restart,start,stop,pause,unpause] <CONTAINER ID>
  • Remove a container: podman rm <CONTAINER ID>

Configuration generation

Kube definition file

  • Generate a kube file: podman generate kube <CONTAINER ID> > <filename>.yaml
  • Import a kube file: podman play kube <filename>.yaml

Systemd units (deprecated since podman 4.4)

  • Pre-requisites: systemctl --user enable podman-restart.service
  • Generate a systemd service unit: podman generate systemd --new <CONTAINER ID> > ~/.config/systemd/user/<CONTAINER NAME>.service
  • Reload systemd: systemctl --user daemon-reload
  • Enable the container to start at boot: systemctl --user enable <CONTAINER NAME>.service

Quadlet

Configuration directories:

  • /usr/share/containers/systemd/
  • /etc/containers/systemd/
  • ~/.config/containers/systemd (rootless)

Create a container file, in example in .config/containers/systemd/httpd.container:

[Unit]
Description=HTTPD server
After=local-fs.target

[Container]
Image=docker.io/library/httpd:latest
#Exec=sleep 1000
AutoUpdate=registry
PublishPort=8080:80 # Port mapping
Volume=%h/public:/var/www/ # %h is mapped to the user home dir
Environment=ENV=prod # Environment variable

[Install]
# Start by default on boot
WantedBy=multi-user.target default.target
  • Reload and scan for local changes: systemctl --user daemon-reload
  • Show the generated service unit: systemctl --user cat httpd
  • Start the container: systemctl --user start httpd

External Resources