Podman can now ease the transition to Kubernetes and CRI-O

Podman can now ease the transition to Kubernetes and CRI-O

Configuring Kubernetes is an exercise in defining objects in YAML files.  While not required, it is nice to have an editor that can at least understand YAML, and it’s even better if it knows the Kubernetes language.  Kubernetes YAML is descriptive and powerful. We love the modeling of the desired state in a declarative language. That said, if you are used to something simple like podman run, the transition to YAML descriptions can be a bitter pill to swallow.

As the development of Podman has continued, we have had more discussions focused on developer use cases and developer workflows.  These conversations are fueled by user feedback on our various principles, and it seems clear that the proliferation of container runtimes and technologies has some users scratching their heads.  One of these recent conversations was centered around orchestration and specifically, local orchestration. Then Scott McCarty tossed out an idea: “What I would really like to do is help users get from Podman to orchestrating their containers with Kubernetes.” And just like that, the proverbial light bulb went on.

A recent pull request to libpod has started to deliver on that very idea. Read on to learn more.

Continue reading “Podman can now ease the transition to Kubernetes and CRI-O”

A Practical Introduction to Container Terminology

A Practical Introduction to Container Terminology

You might think containers seem like a pretty straightforward concept, so why do I need to read about container terminology? In my work as a container technology evangelist, I’ve encountered misuse of container terminology that causes people to stumble on the road to mastering containers. Terms like containers and images are used interchangeably, but there are important conceptual differences. In the world of containers, repository has a different meaning than what you’d expect. Additionally, the landscape for container technologies is larger than just docker. Without a good handle on the terminology, It can be difficult to grasp the key differences between docker and (pick your favorites, CRI-O, rkt, lxc/lxd) or understand what the Open Container Initiative is doing to standardize container technology.


It is deceptively simple to get started with Linux Containers. It takes only a few minutes to install a container engine like docker and run your first commands. Within another few minutes, you are building your first container image and sharing it. Next, you begin the familiar process of architecting a production-like container environment, and have the epiphany that it’s necessary to understand a lot of terminology and technology behind the scenes. Worse, many of the following terms are used interchangeably… often causing quite a bit of confusion for newcomers.

  • Container
  • Image
  • Container Image
  • Image Layer
  • Registry
  • Repository
  • Tag
  • Base Image
  • Platform Image
  • Layer

Understanding the terminology laid out in this technical dictionary will provide you a deeper understanding of the underlying technologies. This will help you and your teams speak the same language and also provide insight into how to better architect your container environment for the goals you have. As an industry and wider community, this deeper understanding will enable us to build new architectures and solutions. Note, this technical dictionary assumes that the reader already has an understanding of how to run containers. If you need a primer, try starting with  A Practical Introduction to Docker Containers on the Red Hat Developer Blog.

Continue reading “A Practical Introduction to Container Terminology”