Delete the lock created by CSO 4.6.

On a downgrade from 4.6 to 4.5 scenario, the leader
election ConfigMap is created by CSO 4.6 (library-go)
and it doesn't have any `ownerReference` set.

However, CSO 4.5 uses `operator-sdk` with
leader-for-life election approach, and it expects
that the ConfigMap either doesn't exist or
exists but has an `ownerReference` set (in order
to know whether the lock belongs to it or not).

Since it doesn't find any, it tries to create one,
but it gets back an error stating the the object
already exists. This goes on forever and CSO 4.5
never become the leader.

This patch identifies if the lock was created
by CSO 4.6 and, if so, deletes it so that CSO 4.5
can become the leader using the leader-for-life model

cmd/manager/main.go

@@ -10,9 +10,14 @@ import (
 	configv1 "github.com/openshift/api/config/v1"
 	"github.com/openshift/cluster-storage-operator/pkg/apis"
 	"github.com/openshift/cluster-storage-operator/pkg/controller"
+	"github.com/operator-framework/operator-sdk/pkg/k8sutil"
 	"github.com/operator-framework/operator-sdk/pkg/leader"
 	sdkVersion "github.com/operator-framework/operator-sdk/version"
+	corev1 "k8s.io/api/core/v1"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/client/config"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	logf "sigs.k8s.io/controller-runtime/pkg/runtime/log"
@@ -27,6 +32,51 @@ func printVersion() {
 	log.Info(fmt.Sprintf("Version of operator-sdk: %v", sdkVersion.Version))
 }
 
+// tryDeleteIncompatibleLock tries to identify a ConfigMap created by CSO 4.6 and delete it.
+// On a downgrade from 4.6 to 4.5 scenario, the leader election ConfigMap is created by CSO 4.6
+// (library-go) and it doesn't have any ownerReference set. However, CSO 4.5 uses the leader-for-life
+// election model, and it expects that the ConfigMap either doesn't exist or exists but has an
+// ownerReference set (in order to know whether the lock belongs to it or not). Without this code,
+// CSO 4.5 will perpetually fail to acquire the lock.
+// More information at https://bugzilla.redhat.com/show_bug.cgi?id=1877316
+func tryDeleteIncompatibleLock(cl client.Client, lockName string) error {
+	namespace, err := k8sutil.GetOperatorNamespace()
+	if err != nil {
+		return err
+	}
+
+	key := client.ObjectKey{Namespace: namespace, Name: lockName}
+	cm := &corev1.ConfigMap{
+		TypeMeta: v1.TypeMeta{
+			APIVersion: "v1",
+			Kind:       "ConfigMap",
+		},
+	}
+
+	err = cl.Get(context.TODO(), key, cm)
+	if apierrors.IsNotFound(err) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+
+	// If the ConfigMap has metadata.ownerReferences, then it was
+	// likely created by CSO 4.5. In this case, we don't want to
+	// delete the lock, otherwise we could end up with multiple
+	// operators running at the same time.
+	if len(cm.GetOwnerReferences()) > 1 {
+		return nil
+	}
+
+	log.Info("Found ConfigMap lock without metadata.ownerReferences, deleting")
+	err = cl.Delete(context.TODO(), cm)
+	if apierrors.IsNotFound(err) {
+		return nil
+	}
+	return err
+}
+
 func main() {
 	flag.Parse()
 
@@ -47,15 +97,24 @@ func main() {
 		os.Exit(1)
 	}
 
-	// Become the leader before proceeding
-	err = leader.Become(context.TODO(), "cluster-storage-operator-lock")
+	// Create a new Cmd to provide shared dependencies and start components
+	mgr, err := manager.New(cfg, manager.Options{Namespace: namespace})
 	if err != nil {
 		log.Error(err, "")
 		os.Exit(1)
 	}
 
-	// Create a new Cmd to provide shared dependencies and start components
-	mgr, err := manager.New(cfg, manager.Options{Namespace: namespace})
+	// Delete incompatible ConfigMap lock if it exists
+	lockName := "cluster-storage-operator-lock"
+	err = tryDeleteIncompatibleLock(mgr.GetClient(), lockName)
+	if err != nil {
+		// We don't exit if an error happens, but we let the operator
+		// try to become the leader below. If it doesn't succeed, then we exit
+		log.Error(err, "error trying to delete incompatible ConfigMap lock")
+	}
+
+	// Become the leader before proceeding
+	err = leader.Become(context.TODO(), lockName)
 	if err != nil {
 		log.Error(err, "")
 		os.Exit(1)