Buildah and Podman Relationship

By Tom Sweeney GitHub​

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 daemon dependencies 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. With Podman you can run, build (it calls Buildah under the covers for this), modify and troubleshoot containers in your Kubernetes cluster. With the two projects together, you have a well rounded solution for your OCI container image and container needs.

Adding checkpoint/restore support to Podman

By Adrian Reber​

With the help of Checkpoint/Restore In Userspace (CRIU) I was able to add initial checkpoint/restore support to Podman. Using checkpoint/restore it is now possible to resume a container after a reboot at exactly the same point in time it was checkpointed.

Upgrade OpenStack TripleO Undercloud from Docker to Podman containers

By Emilien Macchi GitHub​

I wrote a blog post about how we could upgrade OpenStack TripleO Undercloud from Docker to Podman containers.

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Manage Podman containers with systemd

By Emilien Macchi GitHub​

I wrote a blog post about how we manage Podman containers with systemd in OpenStack TripleO.

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Deploy OpenStack TripleO Undercloud Podman containers

By Emilien Macchi GitHub​

I wrote a blog post about how we deploy OpenStack TripleO Undercloud with Podman containers.

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SELinux blocks Podman container from talking to libvirt

By Dan Walsh GitHub​

I wrote a SELinux blog on running a container with Podman. The talks explains why SELinux blocks the connection to the libvirt socket. It then goes on to explain how to setup the container to allow the communication.

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Why can’t I delete storage files created by non-root Podman?

By Dan Walsh GitHub​

Cool things you can do with Podman​

When running Podman as root, the default location for storage is /var/lib/containers/storage. Of course, users cannot use this directory when running as non root, so Podman creates the storage by default in $HOME/.local/share/containers.

Replacing Docker with Podman

By Dan Walsh GitHub​

At the "All Systems Go!" conference on September 28-30, 2018 in Berlin Germany, Dan Walsh gave a talk on how you can replace docker with podman and not skip a beat. The talk was taped and can be viewed here.

The slides in PDF format are here.

Pulling content directly from the Docker Daemon...

By Dan Walsh GitHub​

Cool things you can do with Podman.​

I recently received a bug report about some huge container images not working correctly in Docker. So I suggested to the reporter that they try them with Podman. He responded that he saw the images with docker images, but did not see them with podman images.

I explained to him that the Docker image and container database are separate from the Podman image and container database. I told him he would have to pull the images into Podman. Then I decided to try a cool feature of Podman, where I could pull images directly out of the Docker daemon.

Using systemd to control the startup of Podman containers

By Emilien Macchi GitHub​

Podman wasn't designed to manage containers startup order, dependency checking or failed container recovery. In fact, this job can be done by external tools and this blog post describes how we can use the systemd initialization service to work with Podman containers.