Podman vs Docker Comparison: Which Containerization Tool Should You Use?
When any tech talk turns to container management, Docker comes out as the first topic of discussion. And why not! The tool is the most popular container management engine. It came out in 2014, and since then, it has amassed quite a few big names as its clients, including Google and Facebook.
But Docker is now not the only tool in the market. Recently, Podman has taken charge as a container orchestration tool to help developers to build, package, test, and deploy applications independently across all servers and OS.
Now, the question arises: Podman vs Docker – which is the better tool?
While Docker has been the standard containerization tool for almost a decade and has a loyal customer base, Podman emerges as a problem-solver with its more secure design. Let’s dive deeper into these two tools and how they influence the container management process.
Table Of Contents
- 1 What is Containerization?
- 2 Containers vs Virtual Machines
- 3 Why are Containers Important?
- 4 What is Docker?
- 5 How Does Docker Work?
- 6 What is Podman?
- 7 How Does Podman Work?
- 8 Why Podman vs Docker?
- 9 Podman vs Docker: Detailed Comparison
- 10 Is Podman a replacement for Docker?
- 11 Summary
- 12 Frequently Asked Questions
What is Containerization?
Containerization is a software deployment process that packages all components of an application’s code, such as the files and libraries it needs to run on any system or infrastructure. It is a type of virtualization that allows for developing and deploying codes in isolated user space on the shared OS. The bundled package is called a container. These containers are lightweight, scalable and offer easier techniques to develop, deploy, scale, and debug applications.
Traditionally, to run any application on a system, developers would need to install the version that matched their OS. But with the help of these containers, they can use a single software package that runs on all devices and OS.
But how do they differ from virtual machines?
Containers vs Virtual Machines
Containers and virtual machines are useful for deploying multiple isolated applications on the same system. But how they function differs tremendously.
While virtual machines run on top of an emulating software called the hypervisor, which sits between the hardware and the virtual machine, containers lay on top of the physical server and the host OS. The biggest difference between virtual machines and containers lies in their functions. Virtual machines create a complete machine down to the specific hardware details, but containers only virtualize the software layers on top of the OS and the hardware.
Why are Containers Important?
Containers have their own benefits that help developers easily deploy and maintain microservices that play a major role in managing large-scale projects.
Point to Note: Microservices are little services that communicate, send, and receive data back and forth.
Microservices are responsible for allowing you to work on different parts of your application without interfering with another’s work. They are easy to maintain, flexible to work with, and fairly adaptable. But their deployment is a huge issue, especially in large applications. Since DevOps has become an industry favorite, container management has picked up momentum simultaneously; without it, DevOps teams would need specific instructions to run the code on their side. And if an issue arises, the team would not be able to solve it independently.
Here are a few more reasons why containers are important:
- Containers take a few seconds to run
- They require less memory for storage
- Containers prove to be useful when you need to maximize the running applications using minimal servers
- They are portable, flexible, and agile in their functioning
- Containers are ideal for automation and DevOps pipelines, including CI/CD implementation
What is Docker?
Docker is a standard Platform as a Service (PAAS) that developers use to develop, test, and deploy applications by using containers. It is an open-source platform that enables you to disconnect your application from the system infrastructure and run on the OS-level virtual environment. Docker has become a standalone, self-sufficient container management platform that developers blindly rely on to handle their complex containerization requirements.
It uses a REST API running in the background to manage requests and perform operations, a process called the Docker daemon (or dockerd).
FYI, the Docker daemon is single-handedly responsible for managing all the containers on a single host, including Docker images, networks, containers, and storage.
How Does Docker Work?
The heavy lifting for every Docker client is done by the daemon. Let me explain.
Docker runs on client-server architecture, which means the client interacts with the daemon to initiate creating, testing, and deploying containers. The Docker client can either run on the same OS with the daemon or access it remotely. The connection happens through CLI or REST APIs over a UNIX socket or network interface.
The Docker client is the main means of communication for Docker users with the Docker tool. It sends necessary commands (APIs) to the daemon to manage docker services. One client can interact with more than one daemon.
As mentioned in the same section above, the daemon monitors API requests and controls docker objects like containers, images, volumes, and networks. A daemon can also communicate with other daemons to manage docker services as and when necessary.
Docker images are a read-only set of instructions that are used to create containers. It is often termed the basic building block of Docker, which contains the OS libraries, dependencies, and tools to run an application.
Docker registries are a repository for Docker images; you can either have a public or private registry. For instance, Docker Inc offers a hosted registry service, Docker Hub, which allows you to upload and download images from a central location.
Other Docker hub users can access your images if the repository is public. You can also create a private registry as well within the Docker hub.
Docker containers are the editable part of images. You can start, stop, modify, move, delete, and create a container using CLI or API requests. By default, every container is isolated from other containers and its host machine. You are free to control the process if you wish for two containers to interact with each other or with their network, storage, or other underlying subsystems. Go through this document to learn more about Docker and its containers.
What is Podman?
Podman is a container management tool that has recently sprung out in the market. A product of RedHat, Podman is an open-source, Linux-based tool useful in developing, managing, and running containers as per the Open Container Initiative (OCI) standards. It is often labeled as user-friendly and is the default container engine for RedHat 8 and CentOS 8.
As it follows the OCI standards, Podman is no less than Docker, guiding developers to deploy app container images and containers in a production-ready environment. Although Podman is Linux-backed, you can run the tool on Windows and macOS using a native Podman CLI that embeds a guest Linux system into your system to launch the containers.
Understandably, Podman makes use of daemon-less architecture to create, build and run applications. Instead, the tool leverages the libpod library that contains necessary APIs to manage containers, pods, container images, and volumes.
Point to Note: Pods are a group of containers that run on the same system and share the same resources.
How Does Podman Work?
As already mentioned, Podman works on daemon-less architecture. You can invoke Podman using command lines to request containers you want to run. But instead of making use of the daemon, the tool leverages systemd—a system and service manager for Linux OS—to run and manage containers in the background. By integrating Podman and systemd, you can easily generate and establish control units for the containers and run them automatically.
One of the differentiating factors of Podman for users is being able to run and manage their own repositories on the system. They can further handle systemd units to control the automatic running of containers. Such practices improve overall security and ensure that users have a separate set of containers and images, which they can run on Podman concurrently on the same host without interfering with others.
Similar to Docker, Podman also uses REST APIs to connect with containers. REST API is useful in calling Podman from platforms such as cURL, Postman, Google’s Advanced REST client, and more.
Why Podman vs Docker?
Although Docker is still leading the containerization market, Podman is steadily gaining traction. Podman has been heavily becoming a popular and trending keyword topic in the past few years, especially in Asia. While both container management tools are equally important and workable, the topic of Podman vs Docker emerges for users to decide which one suits them the most.
Individuals, mainly newcomers, sometimes confuse Podman and Docker to function on virtualization. But in reality, they are different in what they do.
So, here are some basic yet critical differences between Podman and Docker that every user should know.
Podman vs Docker: Detailed Comparison
Generally, Podman and Docker have the same functions but differ in a few aspects. And these features are important when it comes to implementing one of these two tools for your DevOps needs.
Here is our take on Podman vs Docker:
Podman has a daemon-less architecture, whereas Docker depends on the daemon to call and manage containers. Daemon handles all the Docker images, containers, networks, and storage.
Docker runs on a client-server that is meditated by the daemon that leverages REST APIs to request to perform container-related operations.
Podman, on the other hand, does not require a daemon. It uses Pods to manage containers, which helps users to run rootless containers. So, you do need to root permission to run containers in Podman.
As discussed above, Docker requires root permissions to manage containers as it runs using the daemon. And because Podman has a daemon-less architecture, you need root permissions to manage containers.
But in one of the recent updates, Docker introduced rootless execution in v19.03. It moved from experimental in Docker Engine v20.10. You would still need to take care of some configurations and third-party packages to run rootless containers on Docker.
The security feature of both Podman and Docker depends upon the root privileges. We do not provide root access to users or applications we don’t trust. But because Docker cannot run rootless as it needs the daemon to access containers, giving root access to everyone is fairly risky and a security hazard.
If someone gains access to one container in Docker, they can misuse all the other containers, images, servers, and more with the same root access.
Podman does not have such security issues because an attacker will harm the containers they have access to but will not be able to gain root access and do further damage to the servers.
So, Podman is considered safer than Docker.
Docker not only manages containers but is also capable of creating images. It is quite self-sufficient and does not require third-party tools for building images.
But Podman is only built to run and manage containers. It is incapable of building images on its own. However, you can use Buildah, an open-source tool, to build Open Container Initiative (OCI) container images. Podman, in integration with Buildah, can build its OCI container images.
In terms of integrations, Docker supports Docker Swarm, a container orchestration platform used to manage Docker containers. It can run a cluster of Docker nodes and deploy scalable applications without external dependencies. You can easily combine Docker with Docker Swarm. But Podman does not support Docker Swarm. Instead, you can add Nomad, which comes with a Podman driver.
Another tool that Docker supports right off the bat is Docker Compose. A tool to manage applications with multiple containers, Docker Compose runs on a single host and automatically connects with Docker.
Again, Podman does not blend with Docker Compose and uses Podman Compose as the alternative.
Independent vs Modular
One of the main differences between Podman vs Docker is their working approach: Docker is independent, while Podman relies on third-party tools for specific tasks.
Docker is monolithic and quite powerful in executing all the necessary containerization tasks independently. But Podman takes on the modules approach and makes use of several integrations to carry out various functions.
Now that we have some context on Podman vs Docker let’s see if one can replace the other. Can Podman, the new addition to container management, be considered a worthy successor for Docker, the all-in-one tool that is reigning in the market?
Is Podman a replacement for Docker?
Podman and Docker have their benefits. While Podman scores more in security, Docker takes the lead in the image development department. Hence, you can move back and forth between the two tools for your operation’s requirements. And as both of them are OCI compliant, compatibility isn’t an issue.
Usually, developers prefer Podman for production to leverage its security feature and Docker for development to easily work around image building.
Overall, Podman cannot always work as a replacement for Docker. But you can definitely use it as your primary containerization tool if you are starting a project. Otherwise, Podman and Docker work well together, and you can employ both for different purposes.
As DevOps has evolved among enterprises, containerization has also picked up pace. There is no other way your DevOps team would be able to work if not with a container management tool. And when talking about such tools, Docker comes to mind automatically. It has been the industry standard for almost a decade and has amassed a pretty good client base.
However, with the need for container management tools to be secure and easy, more tools are still coming out. Podman is one of those recent platforms. It is highly secure and does not have the basic ‘daemon-backed’ architecture Docker employs.
As two sufficient and capable containerization tools make their way to businesses of every size, we help you decipher which one is better for your usage. The several differences between Podman and Docker discussed here are sure to guide you in deciding whether to use either one tool or both in tandem.
Frequently Asked Questions
Is Podman safer than Docker?
Yes, Podman is more secure than Docker because it is rootless and does not require the daemon to call and manage containers.
Why is Podman more secure than Docker?
Podman is more secure than Docker because of its daemon-less architecture, which makes it rootless. The rootless architecture of Podman allows users to work on their own containers or pods without interfering with other containers. It is also useful in stopping attackers from accessing servers that require root access.
Does Kubernetes use Docker or Podman?
Kubernetes works with Podman using pods. A pod is a set of containers and an essential part of the Kubernetes container orchestration framework. Podman also creates Kubernetes-compliant YAML files, which you can transfer to a Kubernetes cluster.
Is Docker still relevant in 2023?
Yes, Docker is still relevant in 2023. It is currently one of the market’s most popular and widely used containerization tools. Developers still prefer Docker for development and management over other tools.
Is Podman slower than Docker?
Yes, Podman is significantly slower in container creation and management than Docker. In Podman vs Docker, Podman takes precedence in security, but Docker comes to the front as the faster tool.