Allow overriding secretKey for kubeconfig

During reconciliation, the control plane provider copies the content from the secret provided by Kamaji, named <cluster>-admin-kubeconfig, into a generic Cluster API secret, <cluster>-kubeconfig, which can then be used by the bootstrap provider and other cluster components.

This change introduces a new annotation, kamaji.clastix.io/kubeconfig-secret-key, for the KamajiControlPlane resource. This annotation instructs the control plane provider to read the kubeconfig from a specific key (the default one is admin.conf).

Example:

```
kamaji.clastix.io/kubeconfig-secret-key: super-admin.svc
```

This will instruct the system to use `super-admin.svc` a kubeconfig with a local service FQDN (introduced by clastix/kamaji#403).

Signed-off-by: Andrei Kvapil <[email protected]>

Author: kvaps

controllers/kamajicontrolplane_controller_resources.go

@@ -147,7 +147,13 @@ func (r *KamajiControlPlaneReconciler) createOrUpdateKubeconfig(ctx context.Cont
 			labels["kamaji.clastix.io/cluster"] = cluster.Name
 			labels["kamaji.clastix.io/tcp"] = tcp.Name
 
-			value, ok := kamajiAdminKubeconfig.Data["admin.conf"]
+			secretKey := "admin.conf"
+			v, ok := kcp.GetAnnotations()["kamaji.clastix.io/kubeconfig-secret-key"]
+			if ok && v != "" {
+				secretKey = v
+			}
+
+			value, ok := kamajiAdminKubeconfig.Data[secretKey]
 			if !ok {
 				return errors.New("missing key from *kamajiv1alpha1.TenantControlPlane admin kubeconfig secret")
 			}