Project Atomic is now sunset

The Atomic Host platform is now replaced by CoreOS. Users of Atomic Host are encouraged to join the CoreOS community on the Fedora CoreOS communication channels.

The documentation contained below and throughout this site has been retained for historical purposes, but can no longer be guaranteed to be accurate.

About Micah Abbott

Quality Enginer for Red Hat focused on Atomic Host.

Creating Custom ostree Composes for Atomic Testing

I recently was tasked with testing a change in the upstream ostree code on an Atomic Host.

Well, since Atomic hosts use ostree as their distribution model, that means I couldn’t just get an RPM and install it that way. (I could have just copied over the compiled binary, but where is the fun in that?)

My task list was as follows:

  1. build ostree from source
  2. package ostree into an RPM
  3. create an custom ostree compose
  4. rebase an existing Atomic host to the custom compose

As someone who hadn’t really accomplished any of these tasks before, I had to reach out for some help on multiple occasions, but I got through it all and hopefully this guide will help you along the way.

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Migrating the Docker Storage Driver to overlay2

On the Project Atomic mailing list, Colin Walters posted a quick set of instructions on how to migrate the Docker storage driver from devicemapper to overlay2 on Fedora Atomic Host.

The overlay2 driver will be the default storage driver in Fedora 26, but you can use it on Fedora 25 Atomic now. To switch storage drivers on an installed system, either before or after you rpm-ostree rebase to Fedora 26, you can use the following procedure.

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Deploying an OpenShift Origin Stand-alone Registry on Fedora 25 Atomic Host

Update: Removed links to Atomic Registry as discontinued.

The Project Atomic site has had a section dedicated to the Atomic Registry, which has been discontinued in favor of OpenShift Registry. It was useful for getting a registry up and running as quickly as possible. However, the software powering the quickstart installation has not always kept up with the OpenShift Origin software which powers the actual registry and web UI. This has lead to an increase in users reporting issues in the #atomic Freenode IRC channel. And often it ends with someone pointing to the stand-alone registry documentation that is provided by the OpenShift Origin project.

It turns out that deploying the stand-alone registry on a single Fedora 25 Atomic Host system is quite straight-forward and can quickly provide a usable registry. In this blog post, we’ll deploy a proof-of-concept stand-alone registry on a single node, which will end up using self-signed certificates in the process. In a later blog post, we’ll show you how to setup a stand-alone registry using multiple nodes and your own SSL certificates.

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The Many Ways to Build an OCI Image without Docker

When containers initially made their big splash into the industry via Docker, users were almost required to use the docker CLI and daemon to create and manage their container images. But a lot has happened since then and now it is easier than ever to create a container image without using docker at all, since the Docker image format has been standardized as the OCI Image format.

In this post, we’ll review some of the ways you can create and manage your container images without ever having to start the docker daemon.

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Fedora 27->28 Atomic Host Upgrade Guide


This week we put out the first release of Fedora 28 Atomic Host. Some quick notes:

  • For Fedora 28 we are using a unified repo that will serve up the Fedora 28 Atomic Host and Atomic Workstation content. This includes all the content for the multi-arch platforms aarch64 and ppcle64.

For today we’ll talk about updating an existing Fedora 27 Atomic Host system to Fedora 28. We’ll cover preparing the system for upgrade and performing the upgrade.

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