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With Red Hat Enterprise Linux 7.5.0 released this week, we wanted to take a look at a few of the container-specific changes for users of Red Hat Enterprise Linux and Red Hat Enterprise Linux Atomic Host.
Buildah Now Fully Supported
With Red Hat Enterprise Linux 7.5, we now fully support using Buildah to create Docker and OCI-compliant container images. Buildah was introduced in 7.4.3 as a tech preview, and moves to fully supported in this release.
With Buildah, you can now create container images without needing to run a container runtime daemon. You can create images from scratch (without a base image) or with a base image such as one of the many Red Hat Enterprise Linux container images provided via the Red Hat Container Catalog.
Buildah also allows you to inspect images and mount their root filesystem, without running the image, to add or change content in the image. It can also be used to manage images and more. See the documentation on Buildah for more on how to integrate this tool into your environment.
Defaulting to OverlayFS
With 7.5, Docker will default to using OverlayFS for storage of container images. This means that users will see better performance and lower memory overhead for working with container images -- which is crucial for environments with heavy Linux container usage.
Note that this is the default for Red Hat Enterprise Linux 7.5, but if you are updating to 7.5 from a prior version of Red Hat Enterprise Linux, your existing defaults will be honored.
Kubernetes and docker-latest deprecated
With Red Hat Enterprise Linux 7.5, we’re finalizing the transition we announced in 2016 with Red Hat Enterprise Linux 7.3 and completely deprecating the Kubernetes RPMs and container images, and we are also retiring the docker-latest package.
The container landscape has changed a great deal since we first included Kubernetes in Red Hat Enterprise Linux Extras, and we’ve learned that simply packaging upstream Kubernetes for customers doesn’t provide the value or utility that customers need for orchestrating containers at scale.
For customers that wish to work with Kubernetes on a single host for testing and development purposes, we recommend the Red Hat Container Development Kit, which provides a pre-built, single node OpenShift Cluster. This will provide the best self-contained environment for non-production use of Kubernetes.
If you plan on production use of Kubernetes, we recommend that customers evaluate Red Hat OpenShift for a fully supported container platform based on Kubernetes.
We are also deprecating the docker-latest package. We initially introduced docker-latest because of the need for stability in container runtime while the upstream churn around new and experimental features was still significant. As Linux container technology has evolved, we are able to provide a stable container runtime that will meet users’ needs.
Join us at Red Hat Summit!
Wondering what’s coming next for containers and Red Hat Enterprise Linux? Join us at Red Hat Summit in San Francisco this May. At Summit you’ll have an opportunity to hear all about the Red Hat Enterprise Linux roadmap, talk to our experts about Red Hat Enterprise Linux and containers, and much more. See you in May!
About the author
Joe Brockmeier is the editorial director of the Red Hat Blog. He joined Red Hat in 2013 as part of the Open Source and Standards (OSAS) group, now the Open Source Program Office (OSPO). Prior to Red Hat, Brockmeier worked for Citrix on the Apache OpenStack project, and was the first OpenSUSE community manager for Novell between 2008-2010.