Podman

IoT edge development and deployment with containers through OpenShift: Part 1

IoT edge development and deployment with containers through OpenShift: Part 1

Usually, we think about IoT applications as something very special made for low power devices that have limited capabilities. For this reason, we tend to use completely different technologies for IoT application development than the technology we use for creating a datacenter’s services.

This article is part 1 of a two-part series. In it, we’ll explore some techniques that may give you a chance to use containers as a medium for application builds—techniques that enable the portability of containers across different environments. Through these techniques, you may be able to use the same language, framework, or tool used in your datacenter straight to the “edge,” even with different CPU architectures!

We usually use “edge” to refer to the geographic distribution of computing nodes in a network of IoT devices that are at the “edge” of an enterprise. The “edge” could be a remote datacenter or maybe multiple geo-distributed factories, ships, oil plants, and so on.

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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.

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Podman: Managing pods and containers in a local container runtime

Podman: Managing pods and containers in a local container runtime

People associate running pods with Kubernetes. And when they run containers in their development runtimes, they do not even think about the role pods could play—even in a localized runtime.  Most people coming from the Docker world of running single containers do not envision the concept of running pods. There are several good reasons to consider using pods locally, other than using pods to naturally group your containers.

For example, suppose you have multiple containers that require the use of a MariaDB container.  But you would prefer to not bind that database to a routable network; either in your bridge or further.  Using a pod, you could bind to the localhost address of the pod and all containers in that pod will be able to connect to it because of the shared network name space.

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Managing containerized system services with Podman

Managing containerized system services with Podman

In this article, I discuss containers, but look at them from another angle. We usually refer to containers as the best technology for developing new cloud-native applications and orchestrating them with something like Kubernetes. Looking back at the origins of containers, we’ve mostly forgotten that containers were born for simplifying application distribution on standalone systems.

In this article, we’ll talk about the use of containers as the perfect medium for installing applications and services on a Red Hat Enterprise Linux (RHEL) system. Using containers doesn’t have to be complicated, I’ll show how to run MariaDB, Apache HTTPD, and WordPress in containers, while managing those containers like any other service, through systemd and systemctl.

Additionally, we’ll explore Podman, which Red Hat has developed jointly with the Fedora community. If you don’t know what Podman is yet, see my previous article, Intro to Podman (Red Hat Enterprise Linux 7.6) and Tom Sweeney’s Containers without daemons: Podman and Buildah available in RHEL 7.6 and RHEL 8 Beta.

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Containers without daemons: Podman and Buildah available in RHEL 7.6 and RHEL 8 Beta

Containers without daemons: Podman and Buildah available in RHEL 7.6 and RHEL 8 Beta

Kubernetes installations can be complex with multiple runtime dependencies and runtime engines. CRI-O was created to provide a lightweight runtime for Kubernetes which adds an abstraction layer between the cluster and the runtime that allows for various OCI runtime technologies. However you still have the problem of depending on daemon(s) in your cluster for builds – I.e. if you are using the cluster for builds you still need a Docker daemon.

Enter Buildah. Buildah allows you to have a Kubernetes cluster without any Docker daemon for both runtime and builds. Excellent. But what if things go wrong? What if you want to do troubleshooting or debugging of containers in your cluster? Buildah isn’t really built for that, what you need is a client tool for working with containers and the one that comes to mind is Docker CLI – but then you’re back to using the daemon.

This is where Podman steps in. Podman allows you to do all of the Docker commands without the daemon dependency. To see examples of Podman replacing the docker command, see Alessandro Arrichiello’s Intro to Podman and Doug Tidwell’s Podman—The next generation of Linux container tools.

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Intro to Podman (Red Hat Enterprise Linux 7.6 Beta)

Intro to Podman (Red Hat Enterprise Linux 7.6 Beta)

Red Hat Enterprise Linux (RHEL) 7.6 Beta was released a few days ago and one of the first new features I noticed is Podman. Podman complements Buildah and Skopeo by offering an experience similar to the Docker command line: allowing users to run standalone (non-orchestrated) containers. And Podman doesn’t require a daemon to run containers and pods, so we can easily say goodbye to big fat daemons.

Podman implements almost all the Docker CLI commands (apart from the ones related to Docker Swarm, of course). For container orchestration, I suggest you take a look at Kubernetes and Red Hat OpenShift.

Podman consists of just a single command to run on the command line. There are no daemons in the background doing stuff, and this means that Podman can be integrated into system services through systemd.

We’ll cover some real examples that show how easy it can be to transition from the Docker CLI to Podman.

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