variants: simplify

This repo is really confusing to work with because of all the various
tiers of variants we have.

In practice, our production pipelines always specify a concrete variant
to build because the switchover between e.g. 9.2 and 9.4 happens on the
ART side, not RHCOS side. And even in CI, since the script that gets
called by Prow lives here, we can easily control which concrete variant
gets built.

So overall, we don't gain much from trying to have symbolic versionless
variants, but it adds cognitive overhead trying to understand it all.

This patch greatly simplifies things by getting rid of the `scos` and
`rhel-coreos-9` variants. Now, we *only* have concrete variants.
Document them in the README.

The only symbolic links left are the canonical variantless ones, which
determine the default variant that gets built if no `--variant` switch
is passed to `cosa init`.

This is also prep for openshift#799, which will add more concrete variants that
do not bake in the OpenShift components.

README.md

@@ -7,6 +7,19 @@ There was a previous git repository inside the Red Hat firewall that was never
 published. The history of that repository is entangled with various private
 things and is omitted. This repository is now canonical.
 
+## Variants
+
+To support building both a RHEL-based and a CentOS Stream-based CoreOS, the
+coreos-assembler concept of [variants] is used. The following variants are
+supported:
+
+- `rhel-9.4`: RHEL 9.4-based CoreOS; including OpenShift components.
+- `c9s`: CentOS Stream-based CoreOS, including OpenShift components. This
+  currently includes some packages from RHEL because not all packages required
+  by OpenShift are provided in CentOS Stream.
+
+The default variant is `rhel-9.4`.
+
 ## Reporting issues
 
 The issue tracker for this repository is only used to track the development
@@ -34,3 +47,4 @@ See [OpenShift CI notes](docs/openshift-ci-notes.md) for more information.
 
 [coreos-assembler]: https://github.com/coreos/coreos-assembler/
 [OKD issue tracker]: https://github.com/openshift/okd/issues
+[variants]: https://github.com/coreos/coreos-assembler/blob/065cd2d20e379642cc3a69e498d20708e2243b21/src/cmd-init#L45-L48

ci/prow-entrypoint.sh

@@ -300,36 +300,36 @@ main() {
             prepare_repos
             ;;
         "build" | "init-and-build-default")  # TODO: change prow job to use init-and-build-default
-            cosa_init "rhel-coreos-9"
+            cosa_init "rhel-9.4"
             cosa_build
             ;;
         "rhcos-cosa-prow-pr-ci")
             setup_user
-            cosa_init "rhel-coreos-9"
+            cosa_init "rhel-9.4"
             cosa_build
             kola_test_qemu
             ;;
         "rhcos-9-build-test-qemu")
             setup_user
-            cosa_init "rhel-coreos-9"
+            cosa_init "rhel-9.4"
             cosa_build
             kola_test_qemu
             ;;
         "rhcos-9-build-test-metal")
             setup_user
-            cosa_init "rhel-coreos-9"
+            cosa_init "rhel-9.4"
             cosa_build
             kola_test_metal
             ;;
         "scos-9-build-test-qemu")
             setup_user
-            cosa_init "scos"
+            cosa_init "c9s"
             cosa_build
             kola_test_qemu
             ;;
         "scos-9-build-test-metal")
             setup_user
-            cosa_init "scos"
+            cosa_init "c9s"
             cosa_build
             kola_test_metal
             ;;

extensions.yaml

@@ -1 +1 @@
-extensions-rhel-coreos-9.yaml
+extensions-rhel-9.4.yaml

image.yaml

@@ -1 +1 @@
-image-rhel-coreos-9.yaml
+image-rhel-9.4.yaml

manifest.yaml

@@ -1 +1 @@
-manifest-rhel-coreos-9.yaml
+manifest-rhel-9.4.yaml