The CoreOS Assembler

This is the CoreOS Assembler (often abbreviated COSA) build environment. It is a collection of various tools used to build [Fedora CoreOS][fcos] style systems, including RHEL CoreOS. The goal is that everything needed to build and test the OS comes encapsulated in one (admittedly large) container.

A high level goal of this tool is to support two highly related use cases, and to keep them as similar as possible:

• Local development ("test a kernel change")
• Be a production build system orchestrated by an external tool (e.g. Jenkins)

The container itself is available on Quay.io at [quay.io/coreos-assembler/coreos-assembler][quay-cosa]. It includes the following tools:

• cosa: entrypoint for the COSA container and dispatcher to other

• kola: for launching instances and running tests on them
• kolet: an agent for kola that runs on instances
• ore: for interfacing with cloud providers
• plume: for releasing Fedora CoreOS and Fedora Cloud

Building Fedora CoreOS

See the Building Fedora CoreOS guide to learn how to build Fedora CoreOS with COSA.

Building a custom OS with COSA

For more information about building a custom OS derived or based on Fedora CoreOS, see Custom OS.

[fcos]: https://coreos.fedoraproject.org [pipeline]: https://github.com/coreos/fedora-coreos-pipeline [quay-cosa]: https://quay.io/repository/coreos-assembler/coreos-assembler