Cloud Native 18 min read

Podman Tutorial: Overview, Differences from Docker, Common Commands, Installation, Configuration, and Usage

This article provides a comprehensive guide to Podman, covering its definition, key differences from Docker, essential CLI commands for containers and images, installation steps, registry accelerators, rootless operation, user namespace handling, volume usage, and configuration files for effective container management on Linux systems.

Top Architect

Jun 6, 2023

Podman Tutorial: Overview, Differences from Docker, Common Commands, Installation, Configuration, and Usage

This guide introduces Podman, an open‑source container runtime that works on most Linux platforms without requiring a daemon or root privileges.

What Is Podman?

Podman can run any OCI‑compatible container or image and offers a Docker‑compatible command‑line interface while operating daemon‑less and optionally rootless.

Main Differences Between Podman and Docker

Docker relies on a root‑owned daemon (dockerd) and requires root privileges for many operations, creating security concerns.

Podman runs without a daemon and can operate without root, making its architecture simpler and more secure.

Docker uses a chain of daemons (dockerd → containerd → containerd‑shim → runc); Podman calls OCI runtimes directly (runc) and uses a per‑container conmon process similar to Docker’s containerd‑shim.

Common Podman Commands

Container Management

podman run          # Create and start a container
podman start        # Start a stopped container
podman ps           # List containers
podman stop         # Stop a container
podman restart      # Restart a container
podman attach       # Attach to a running container
podman exec         # Execute a command in a container
podman export       # Export a container's filesystem
podman import       # Import a container snapshot
podman rm           # Remove a container
podman logs         # View container logs

Image Management

podman search       # Search for images
podman pull         # Pull an image
podman images       # List images
podman rmi          # Remove an image
podman save         # Export an image
podman load         # Import an image
podman build        # Build an image from a Dockerfile
podman tag          # Tag an image

Installation

# yum -y install podman

Registry Accelerators (Mirrors)

Version 7 configuration example:

# vim /etc/containers/registries.conf
registries = ["docker.io"]
[[docker.io]]
location = "j3m2itm3.mirror.aliyuncs.com"

Version 8 configuration example:

unqualified-search-registries = ["docker.io"]
[[registry]]
prefix = "docker.io"
location = "j3m2itm3.mirror.aliyuncs.com"

Basic Usage Examples

Run an HTTPD container:

# podman run -d --name httpd docker.io/library/httpd
# podman images
REPOSITORY               TAG      IMAGE ID       CREATED       SIZE
docker.io/library/httpd   latest   ea28e1b82f31   11 days ago   148 MB

List running containers:

# podman ps
CONTAINER ID  IMAGE                     COMMAND               CREATED          STATUS               PORTS  NAMES
0492e405b9ec  docker.io/library/httpd   httpd-foreground    About a minute ago  Up About a minute ago        httpd

Inspect the latest container to view its IP address (rootless containers have no IP):

# podman inspect -l | grep IPAddress
"IPAddress": "10.88.0.5",
# curl 10.88.0.5
<html><body><h1>It works!</h1></body></html>

Rootless Operation and Port Mapping

Rootless users cannot bind privileged ports (<1024) unless the kernel parameter is adjusted:

# echo 'net.ipv4.ip_unprivileged_port_start=80' >> /etc/sysctl.conf
# sysctl -p
net.ipv4.ip_unprivileged_port_start = 80
# podman run -d -p 80:80 httpd   # now works for rootless users

User Namespace and Volume Sharing

Mount a host directory into a container and keep file ownership consistent by using --userns=keep-id:

# podman run -it -v "$(pwd)"/data:/data --userns=keep-id docker.io/library/busybox /bin/sh
# ls -l /data
-rw-r--r-- 1 zz zz 11 Dec 13 00:21 123

Configuration Files

Podman reads configuration in the following order (higher priority overrides lower):

~/.config/containers/containers.conf

/etc/containers/containers.conf

/usr/share/containers/containers.conf

Key files include containers.conf, storage.conf, and registries.conf. Example storage.conf snippet to use the overlay driver and fuse‑overlayfs:

# /etc/containers/storage.conf
[storage]
driver = "overlay"
mount_program = "/usr/bin/fuse-overlayfs"

Additional Topics

Installation of supporting tools for rootless mode (crun, slirp4netns, fuse‑overlayfs) and configuration of subuid/subgid files are required for proper user namespace mapping.

Overall, Podman provides Docker‑compatible functionality while eliminating the need for a privileged daemon, supporting rootless operation, and offering flexible configuration for modern cloud‑native workflows.

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CLI Docker Linux Container Podman Rootless OCI

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Top Architect

Top Architect focuses on sharing practical architecture knowledge, covering enterprise, system, website, large‑scale distributed, and high‑availability architectures, plus architecture adjustments using internet technologies. We welcome idea‑driven, sharing‑oriented architects to exchange and learn together.

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