Zstreaming a kernel release

Steps to do when a kernel stream is to be released.

This page has an internal companion page which might contain additional information.

Background

Every once in a while, a RHEL stream is released. As CKI needs to run with matching environment, we need to update our setup to match this, in an order that doesn’t break the runs in between.

Timeline and requirements

There is no hard timeline on when these changes need to be put in place. The only requirement to start the process is to have the kernel zstream branch created by the maintainers. This happens pretty early, and is announced on kernel-info. Of course, the steps requiring the ystream compose and zstream containers need to wait for their availability.

A good indicator to start the process is the kernel maintainers changing the kernel makefile configuration to officially tag the new zstream, or a new source-git branch is created. This usually happens around the RC release of the new zstream compose.

Package dependencies and conflicts between the new zstream and ystream may increase the priority of the changes on CKI side. This can happen e.g. when the new ystream kernel or the tests start requiring package versions only available in the new ystream compose. If this is the case, kernel or test maintainers will point it out, or we’ll notice the new pipelines consistently failing.

Steps to take

Add the zstream branch to the gitlab-ci-bot config.
In kpet-db, create a new zstream tree. The tree should match the ystream tree for now. Also update the nvr tree mapping configuration accordingly. As the new trees will use nightly composes, the ystream composes file also needs to be updated. Add a new line for the tree with the same name as defined in kpet-db and set the distro_name to the prefix for the beaker compose such as
```
rhel810-z: {distro_name: RHEL-8.10%}
```
the bot_comment section also needs to be updated to add the call for the brew build of the tree, like:
```
- `[brew/rhel8.10]`
```
Wait for the kernel maintainer to submit an MR to the kernel repository that (1) adds a new disttag_override value to all pipelines in the new zstream branch, and (2) updates the stream disttag in one of the redhat/Makefile.* files. Review the MR, and check the MR pipeline picks the new zstream kpet tree.
Now that zstream kernels will not use the ystream tree file anymore, everything is ready to update the ystream tree file in kpet-db to point to the new ystream compose.
Once the RHEL zstream is GA, a new UBI container should become available. Create a new builder container image from it. You should be able to copy the definition of an older zstream container image and only override the stream value.
In kpet-db, the zstream tree needs to be updated to the released compose. Also the ystream composes file needs to be updated to remove the tree.
Create an MR to the kernel repository for the zstream branch to switch the builder_image to the newly created container image.
Add the new container image to the .pipeline_images job template in the CKI GitLab CI/CD templates in cki-lib.