ClusterClass in different namespace than Cluster not supported by CSO

Start by reproducing the kubectl sequence in the issue with the Cluster in tenant-1 and the ClusterClass or ClusterStackRelease in cluster-stacks. Trace the validation lookup that reports the ClusterStackRelease as missing; done means the cross-namespace ClusterClass and ClusterStackRelease are found and the warning no longer occurs.

/kind bug

@garloff @janiskemper @jschoone

What steps did you take and what happened:

Namespace A:

kubectl get clusterstack -n cluster-stacks
NAME                 PROVIDER    CLUSTERSTACK   K8S    CHANNEL   AUTOSUBSCRIBE   USABLE   LATEST                             AGE    REASON   MESSAGE    
openstack-scs-1-35   openstack   scs            1.35   stable    true            v4       openstack-scs-1-35-v4 | v1.35.3    6d5h      

kubectl get clusterclasses.cluster.x-k8s.io -n cluster-stacks
NAME                    VARIABLES READY   AGE
openstack-scs-1-34-v1   True              6d4h
openstack-scs-1-35-v3   True              6d4h
openstack-scs-1-35-v4   True              28m

Namespace B:

kubectl get clusteraddons.clusterstack.x-k8s.io -n tenant-1
NAME                                 CLUSTER                    HOOK   READY   AGE    REASON   MESSAGE
cluster-addon-tenant-1-cluster-1     tenant-1-cluster-1                true    20d

kubectl get cluster -n tenant-1
NAME                   CLUSTERCLASS            AVAILABLE   CP DESIRED   CP AVAILABLE   CP UP-TO-DATE   W DESIRED   W AVAILABLE   W UP-TO-DATE   PHASE         AGE    VERSION
tenant-1-cluster-1     openstack-scs-1-35-v4   True        3            3              3               4           4             4              Provisioned   641d   v1.35.3

kubectl get cluster -n tenant-1 tenant-1-cluster-1 -o yaml
apiVersion: cluster.x-k8s.io/v1beta2
kind: Cluster
metadata:
[...]
  name: cluster-1
  namespace: tenant-1-cluster-1
[...]
spec:
  topology:
    classRef:
      name: openstack-scs-1-35-v4
      namespace: cluster-stacks
[...]

Leads to:

Warning: cannot validate clusterClass and Kubernetes version. Getting clusterStackRelease object failed: clusterclass does not exist: ClusterStackRelease.clusterstack.x-k8s.io "openstack-scs-1-35-v4" not found
cluster.cluster.x-k8s.io/tenant-1-cluster-1 configured

What did you expect to happen:

ClusterClass / ClusterStackRelease is found.

Anything else you would like to add:

Maybe CSO does not correctly support storing the ClusterStack in another namespace than the cluster?

Environment:

• cluster-stack-operator version: v0.2.0-alpha.1