Tech Tutorial: Manage Containers with Podman and Skopeo #

Introduction #

In the world of Red Hat Enterprise Linux (RHEL), container management is an essential skill for system administrators. This tutorial will cover how to manage containers using podman and skopeo, two powerful tools in the Red Hat ecosystem. By the end of this guide, you will understand how to effectively use these tools to handle container images and containers.

Podman is a daemonless container engine for developing, managing, and running OCI Containers on your Linux System. Containers can either be run as root or in rootless mode. Unlike Docker, it does not require a running daemon. This can be advantageous for system administrators seeking to manage containers without the overhead or security implications of a daemon.

Skopeo is a command-line utility that performs various operations on container images and image repositories. Skopeo can inspect a repository on a container registry without pulling the image. It allows you to copy container images between various repositories, convert between image formats, and more, all without needing an elevated permissions, daemon, or even Docker.

Step-by-Step Guide #

1. Installing Podman and Skopeo #

First, ensure that you are running RHEL 8 or newer, as podman and skopeo are included in these versions by default.

To install Podman and Skopeo, you can run the following commands:

sudo dnf install -y podman skopeo

2. Managing Containers with Podman #

Pulling a container image #

To download a container image from a registry, use the following command:

podman pull docker.io/library/ubuntu:latest

This command pulls the latest Ubuntu image from the Docker official registry.

Listing images #

To list all downloaded images:

podman images

Running a container #

To run a container interactively:

podman run -it --name myubuntu ubuntu /bin/bash

This command starts an interactive Bash shell inside the Ubuntu container.

Viewing running containers #

To see all running containers:

podman ps

To view all containers, including stopped ones:

podman ps -a

Stopping a container #

To stop a running container:

podman stop myubuntu

Removing a container #

To remove a stopped container:

podman rm myubuntu

3. Managing Container Images with Skopeo #

Inspecting an image #

To inspect an image on Docker Hub without pulling it:

skopeo inspect docker://docker.io/library/ubuntu:latest

This command gives you the JSON output with all the configuration details of the Ubuntu image.

Copying an image #

To copy an image from Docker Hub to another registry:

skopeo copy docker://docker.io/library/ubuntu:latest docker://myregistry.local/ubuntu:latest

Make sure to replace myregistry.local with your actual registry URL.

Deleting an image #

To delete an image from a local registry:

skopeo delete --creds username:password docker://myregistry.local/ubuntu:latest

4. Advanced Podman Usage #

Creating and managing pods #

Podman allows you to create your own pods, which are groups of one or more containers that share the same network namespace, among other resources.

podman pod create --name mypod

Adding a container to the pod:

podman run -d --pod mypod nginx

Listing pods:

podman pod list

Conclusion #

Podman and Skopeo offer robust, flexible tools for container management without the overhead of a daemon, suitable for both development and production environments in RHEL. By mastering these tools, you can significantly enhance your capabilities in managing containers and container images efficiently. Whether you are preparing for the RHCSA exam or looking to improve your container management skills, understanding and utilizing podman and skopeo are essential for any Red Hat system administrator.