Move OCP to floating bootimages #36
Description
Capturing this here for now.
Since OCP moved to using pure RHEL disk images, we can share disk images across multiple OCP releases. But that's awkward today because rhcos.json still lives in the installer, which still branches per OCP release. So e.g. when doing a new bootimage bump for RHEL 9.6, we'd need to PR all of release-4.19, release-4.20, and release-4.21.
Or... we just move to a model like FCOS where there is no longer an rhcos.json, but rather a canonical location for stream metadata which is consulted during deployments. Probably would make sense to have that live on mirror.openshift.com since that already hosts the disk images.
So then, bootimage bumps would just require bumping one central location (but probably ART would still then download the artifacts in there and put them on the mirrors). But also, it could change the story for MCO bootimage updates, because now node scale up could just consult the stream metadata to always use e.g. the latest AMI.
See also openshift/enhancements#1637 (comment).