Podman

Monitoring container vitality and availability with Podman

Monitoring container vitality and availability with Podman

Not long after Podman developed a certain level of stability and functionality we started to hear questions like, “What about container healthchecks?” It was a tough question with no easy, obvious answers. My colleagues and I would occasionally discuss healthchecks, but we are a daemonless environment, which makes this kind of thing challenging. Without a long-running process or daemon to schedule healthchecks, we needed to look at other parts of the operating system to launch them. Recently, the questions grew more pronounced, and it was high time we resolved this for our users.

I am pleased to say that the latest Podman release 1.2 now has the ability to perform container healthchecks. This article describes healthchecks and explains how we implemented them for Podman.

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Build and run Buildah inside a Podman container

Build and run Buildah inside a Podman container

This past Christmas I gave my wife a set of nesting dolls similar to Russian Matryoshka dolls. If you’re not familiar with them, they consist of a wooden doll, which opens to reveal another doll, inside which you’ll find another doll, and so on until you get to the smallest and often most ornate doll of them all.  This concept got me thinking about nesting containers.

I thought I’d try building my own nesting container using Podman to create a container in which I could do Buildah development and also spin up Buildah containers and images. Once this Podman container was created, I could move it to any Linux platform that supported Podman and do development on Buildah from it. In this article, I’ll show how I set it up.

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Creating and deploying a Java 8 runtime container image

Creating and deploying a Java 8 runtime container image

A Java runtime environment should be able to run compiled source code, whereas a development kit, for example, OpenJDK, would include all the libraries/binaries to compile and run the source code. Essentially the latter is a superset of the runtime environment. More details on OpenJDK support and lifecycle can be found here.

Red Hat ships and supports container images with OpenJDK for both Java 8 and 11. More details are here. If you are using Red Hat Middleware, the s2i images shipped are also useful to deploy, for example, on Red Hat Openshift Container Platform.

Note that Red Hat only provides OpenJDK-based Java 8 and 11 images. With that said, there will certainly be situations where developers would like to create their own Java runtime images. For example, there could be reasons such as minimizing storage to run a runtime image. On the other hand, a lot of manual work around libraries such as Jolokio or Hawkular and even security parameters would need to be set up as well. If you’d prefer not to get into those details, I would recommend using the container images for OpenJDK shipped by Red Hat.

In this article we will:

  • Build an image with Docker as well as Buildah.
  • We will run that image with Docker as well as Podman on localhost.
  • We will push our image to Quay.
  • Finally, we will run our app by importing a stream into OpenShift.

This article was written for both OpenShift 3.11 and 4.0 beta. Let’s jump right into it.

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Podman and Buildah for Docker users

Podman and Buildah for Docker users

I was asked recently on Twitter to better explain Podman and Buildah for someone familiar with Docker.  Though there are many blogs and tutorials out there, which I will list later, we in the community have not centralized an explanation of how Docker users move from Docker to Podman and Buildah.  Also what role does Buildah play? Is Podman deficient in some way that we need both Podman and Buildah to replace Docker?

This article answers those questions and shows how to migrate to Podman.

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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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