liminfoPodman Reference
Free reference guide: Podman Reference
About Podman Reference
The Podman Reference is a practical command cheat sheet for Podman, the daemonless OCI-compatible container engine developed by Red Hat. It covers five categories: container lifecycle management (podman run, ps, stop, rm, logs, exec, inspect), image operations (podman build from Containerfile/Dockerfile, pull, push, images list, rmi), Pod management (podman pod create, start/stop, ps), systemd integration (podman generate systemd for creating unit files, podman auto-update with registry labels), and Kubernetes interoperability (podman play kube to run containers from YAML, podman generate kube to export existing containers, and podman-compose for Docker Compose compatibility).
Podman is the preferred container runtime on RHEL, Fedora, and CentOS systems, and it is gaining adoption as a rootless, daemonless alternative to Docker. Unlike Docker, Podman runs containers without a central daemon, supports rootless containers natively, and integrates directly with systemd for container lifecycle management. This reference is useful for DevOps engineers, sysadmins, and developers working in Red Hat ecosystems or looking for a Docker-compatible CLI without a daemon.
The reference is organized to follow typical Podman workflows: pull and build images, run and manage containers, group related containers into Pods, integrate running containers with the host's systemd for auto-start on boot, and bridge between Podman and Kubernetes by generating or consuming Kubernetes YAML manifests. Every command entry includes a complete example with common flags.
Key Features
- Container management: podman run with -d/-p/--name flags, ps -a, stop, rm -f, logs -f, exec -it
- Container inspection with podman inspect for detailed JSON config and network info
- Image operations: podman build -t, pull from docker.io, push to registry, images --filter, rmi -a
- Pod creation and management: podman pod create with port mapping, pod start/stop, pod ps
- Systemd integration: podman generate systemd --new --files for unit file creation
- podman auto-update with io.containers.autoupdate=registry label for automatic image updates
- Kubernetes bridge: podman play kube to run from YAML, podman generate kube to export pods
- podman-compose for Docker Compose file compatibility (up -d, down)
Frequently Asked Questions
What is Podman and how is it different from Docker?
Podman (Pod Manager) is an OCI-compatible container engine that runs containers without a central daemon process. Unlike Docker, which requires a dockerd daemon running as root, Podman runs each container as a direct child process, supports rootless containers (running as a non-root user natively), and integrates with systemd for container lifecycle management. The Podman CLI is designed to be Docker-compatible, so most `docker` commands work with `podman` as a drop-in replacement.
How do I run a container in the background with Podman?
Use `podman run -d -p 8080:80 --name web nginx:alpine`. The `-d` flag runs the container in detached (background) mode. `-p 8080:80` maps host port 8080 to container port 80. `--name web` gives the container a human-readable name for use with other commands like `podman logs web` or `podman exec -it web /bin/sh`. Use `podman ps` to verify it is running and `podman stop web` to stop it.
What is a Podman Pod and how does it differ from a standalone container?
A Podman Pod is a group of containers that share the same network namespace, meaning they can communicate via localhost and share port mappings. This is similar to a Kubernetes Pod. Create a pod with `podman pod create --name mypod -p 8080:80`, then run containers inside it by adding `--pod mypod` to `podman run`. Pods are useful when you have tightly coupled services (e.g., an app container and a sidecar proxy) that need to share network context.
How do I make a Podman container start automatically on system boot?
Use `podman generate systemd --name web --new --files` to generate a systemd unit file for the container named "web". The `--new` flag makes the unit file recreate the container on start rather than just starting an existing one. Copy the generated unit file to `~/.config/systemd/user/` (for rootless) or `/etc/systemd/system/` (for root), then run `systemctl --user enable container-web.service` to enable autostart. For rootless containers, also run `loginctl enable-linger $USER`.
How does podman auto-update work?
`podman auto-update` checks all running containers that have the label `io.containers.autoupdate=registry` and pulls updated images from the registry. If a newer image is available, the container is recreated with the new image. Add the label when creating the container or in the Containerfile. When combined with systemd, create a systemd timer that runs `podman auto-update` periodically (or use the built-in `podman-auto-update.timer` on Fedora/RHEL) to enable automatic image updates without manual intervention.
How do I run a Kubernetes YAML manifest with Podman?
Use `podman play kube deployment.yaml` to create and run containers from a Kubernetes Pod or Deployment YAML manifest. Podman supports a subset of Kubernetes YAML including Pod specs, persistent volume claims, and ConfigMaps. This is useful for local development and testing of Kubernetes workloads without a full cluster. Use `podman play kube --down deployment.yaml` to stop and remove the created resources.
How do I export an existing Podman Pod to Kubernetes YAML?
Use `podman generate kube mypod > pod.yaml` to generate a Kubernetes-compatible YAML file from a running or stopped Pod. This YAML can be applied to a real Kubernetes cluster with `kubectl apply -f pod.yaml`. The generated YAML includes container specs, port mappings, and environment variables. This makes Podman a useful local development tool for building workloads that will eventually run in Kubernetes.
Can I use Docker Compose files with Podman?
Yes. Install `podman-compose` (a Python tool, not part of Podman core) and use `podman-compose up -d` to start services defined in a `docker-compose.yml` file, and `podman-compose down` to stop them. Podman also supports `podman compose` (using a Docker Compose-compatible backend) in newer versions. Most Docker Compose v2 syntax is supported, though some advanced features like network aliases may behave differently.