Podman vs Docker: Comparing the Two Containerization Tools

Containers offer you powerful tools for developing and deploying applications. They give you distinct and portable virtual environments with a fraction of the overhead of traditional virtual machines.

If you’re looking into containerization, you’ve likely seen Docker, the most popular and widely used containerization tool. But recently a capable and compelling alternative has risen, Podman.

Both tools follow the Open Container Initiative (OCI) standards, and both offer robust capabilities for running and managing containers.

So which one should you use? What features make Docker best for some use cases and Podman better for others?

This tutorial aims to help you answer these questions. Learn the key characteristics of each tool, see a breakdown of their pros and cons, and walk through an analysis of each tool’s best use cases.

What Are Containers?

Containers are lightweight and standalone virtual environments for applications. With containers, you can run multiple application environments on a single system or package application environments as images for others to easily run on different systems.

Each container works off a set of instructions, allowing it to replicate the necessary virtual infrastructure and applications. The container then houses and manages the applications and all of their dependencies.

A container can be rendered to a container image. Such an image can then be used to construct the base container on other systems, only requiring a containerization tool, like Docker or Podman.

Today, most containerization tools follow the OCI standards. Any containerization tools that conform to this standard can operate OCI containers built from other such tools. Thus, Podman can run containers built with Docker, and vice versa.

What Is Docker?

Docker is a platform for creating, deploying, and managing applications via containers. With Docker, you can create OCI-compliant containers using Dockerfiles (scripts for container creation) or existing container images.

Docker has become an incredibly popular containerization tool, at least in part due to its relative simplicity. Its straightforward commands and the wealth of available documentation make Docker immanently approachable.

Learn more about Docker in our guide An Introduction to Docker.

What Is Podman?

Podman, like Docker, is an open source engine for deploying and managing containerized applications. Podman builds OCI-compliant containers from existing images or from Containerfiles and Dockerfiles.

The Podman engine was originally developed by Red Hat with the intention of providing a daemonless alternative to Docker. By employing a daemonless architecture, Podman seeks to remedy security concerns around Docker’s daemon-based process.

Additionally, Podman’s daemonless architecture grants it a truly rootless mode. Docker commands can be run by non-root users, but its daemon that executes those commands continues to run on root. Podman, instead, executes commands directly and avoids the need for root privileges.

Learn more about getting started with Podman in our guide How to Install Podman for Running Containers.

Docker vs Podman

Both Podman and Docker are containerization tools. With either one, you can fully start up, deploy, and manage containers.

However, each tool has its pros and cons. These next couple of sections explore each, providing a list to compare and contrast the two containerization engines.

Afterwards, keep on reading to see our advice on which tool to use when.

Docker Pros and Cons

Docker Pros:

• Simple and approachable. Docker’s commands are designed to be relatively simple and easy to use. Alongside that, Docker maintains one of the most frequently used registries for container images.

  The Docker Hub holds a wide collection of well-maintained container images, many of which are composed and updated officially. This makes it relatively easy to, for example, pull a container image for a LAMP stack and start working quickly with Docker.

• Popular. Docker’s widespread usage means you are more likely to encounter it anywhere that works with containers. It also means you have a vast and easily accessible collection of user documentation and troubleshooting to pull from.

Docker Cons:

• Daemon-based architecture. Docker runs on a long-running daemon process, which may pose security concerns for some. Additionally, that daemon process runs with root privileges. Thus, even limited users executing Docker commands are getting those commands fulfilled by a process with root privileges, a further security concern.

Podman Pros and Cons

Podman Pros:

• Daemonless architecture. Podman directly interacts with containers and container images, without a long-running daemon process. Doing so reduces exposure to security risks.

• Rootless processes. Because of its daemonless architecture, Podman can perform truly rootless operations. Users do not have to be granted root privileges to run Podman commands, and Podman does not have to rely on a root-privileged process.

• Access to image registries. Podman can find and pull container images from numerous registries, including the Docker Hub. This means, with a little configuration, Podman can access the same image registries as Docker.

Podman Cons:

• Limited build features. Podman concerns itself primarily with running and managing containers. It can build containers and render them as images, often effectively for many use cases. However, its functionality for doing so represents a limited portion of the Buildah source code.

  Instead, Podman endorses using Buildah as a complimentary tool for more feature-rich container building and fine-tuned control over the process.

Which One Should You Use?

Docker and Podman each stand as viable containerization options. Each tool has a lot to offer, and for most containerization needs, either one works just as well as the other.

But in what cases should you consider one of these two tools over the other?

When to Use Docker

Docker is best suited for when you want a more approachable containerization option. Docker’s design makes it relatively quick to pick up, and its feature set includes everything you’re likely to need when working with containers.

Docker covers the full container life cycle, from container composition to deployment and maintenance. And it accomplishes this with a straightforward set of commands.

Docker has established usage with many companies and has a proliferation of people experienced with it. When it comes to containerization tools, you are more likely to find people familiar with Docker than most other tools.

Looking to go forward with Docker? Be sure to reference the guide linked above, as well as our guide When and Why to Use Docker. To see Docker in action, you may also want to look at our guide on How to install Docker and deploy a LAMP Stack.

When to Use Podman

Podman offers higher security options. Its daemonless architecture allows you to run rootless containers. This, combined with Podman’s direct (rather than long-running) processes for managing containers further secure them.

Podman is a lightweight and specialized solution. It focuses on running, deploying, and managing containers, and gives you fine-grained control of these processes.

At the same time, options for building containers and images are available, though limited. Podman keeps tightly focused on its specialization and prefers to work with Buildah as a complimentary tool for building containers and container images.

This specialization and light footprint are useful in contexts where you want more control for running and managing containers, but don’t need the more advanced build capabilities (or are able to rely on another tool for them).

In fact, you can effectively use Docker and Podman side-by-side, considering both tools are OCI-compliant. For instance, you can use Docker for your development environment, where you are creating application images but security is less of a concern. Then, use Podman to run and maintain those images in a production environment.

Start moving forward with Podman by checking out our guide How to Install Podman for Running Containers. You may also be interested in taking a look at Buildah via our guide How to Use Buildah to Build OCI Container Images.

Conclusion

You now have the knowledge needed to make a decision between Podman and Docker. Both are OCI-compliant containerization tools, each offering particular advantages. Each tool stands as a robust option for running, deploying, and managing containers. Which one you choose comes down to what particular features and use cases you need to cover.

More Information

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

• Red Hat Developer: Podman and Buildah for Docker Users
• phoenixNAP: Podman vs Docker - Everything You Need to Know
• How-to Geek: What Is Podman and How Does It Differ from Docker?