Available CRDs check feature

Reasons for this enhancement:
- A controller cannot set up a watch for a CRD that is not installed on the cluster, trying to set up a watch will panic the operator
- There is no known way, that we are aware of, to add a watch later without client cache issue

How does the enhancement work around the issue:
- A new controller to watch creation/deletion for the CRDs of interest to prevent unnecessary reconciles
- On start of the operator(main), detect which CRDs are avail (out of a fixed list)
- At the start each reconcile of new controller, we fetch the CRDs available again and compare it with CRDs fetched in previous step, If there is any change, we panic the op

Co-Authored-By: Rewant Soni <[email protected]>

controllers/crd/crd_controller.go

@@ -0,0 +1,73 @@
+package crd
+
+import (
+	"context"
+	"github.com/go-logr/logr"
+	"github.com/red-hat-storage/ocs-operator/v4/controllers/util"
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
+	"k8s.io/klog/v2"
+	"reflect"
+	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/builder"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/event"
+	"sigs.k8s.io/controller-runtime/pkg/predicate"
+	"sigs.k8s.io/controller-runtime/pkg/reconcile"
+)
+
+// CustomResourceDefinitionReconciler reconciles a CustomResourceDefinition object
+// nolint:revive
+type CustomResourceDefinitionReconciler struct {
+	Client        client.Client
+	ctx           context.Context
+	Log           logr.Logger
+	AvailableCrds map[string]bool
+}
+
+// Reconcile compares available CRDs maps following either a Create or Delete event
+func (r *CustomResourceDefinitionReconciler) Reconcile(ctx context.Context, request reconcile.Request) (reconcile.Result, error) {
+	r.ctx = ctx
+	r.Log.Info("Reconciling CustomResourceDefinition.", "CRD", klog.KRef(request.Namespace, request.Name))
+
+	var err error
+	availableCrds, err := util.MapCRDAvailability(ctx, r.Client, util.CRDList...)
+	if err != nil {
+		return reconcile.Result{}, err
+	}
+	if !reflect.DeepEqual(availableCrds, r.AvailableCrds) {
+		r.Log.Info("CustomResourceDefinitions created/deleted. Restarting process.")
+		panic("CustomResourceDefinitions created/deleted. Restarting process.")
+	}
+	return reconcile.Result{}, nil
+}
+
+// SetupWithManager sets up a controller with a manager
+func (r *CustomResourceDefinitionReconciler) SetupWithManager(mgr ctrl.Manager) error {
+	crdPredicate := predicate.Funcs{
+		CreateFunc: func(e event.TypedCreateEvent[client.Object]) bool {
+			crdAvailable, keyExist := r.AvailableCrds[e.Object.GetName()]
+			if keyExist && !crdAvailable {
+				r.Log.Info("CustomResourceDefinition %s was Created.", e.Object.GetName())
+				return true
+			}
+			return false
+		},
+		DeleteFunc: func(e event.TypedDeleteEvent[client.Object]) bool {
+			crdAvailable, keyExist := r.AvailableCrds[e.Object.GetName()]
+			if keyExist && crdAvailable {
+				r.Log.Info("CustomResourceDefinition %s was Deleted.", e.Object.GetName())
+				return true
+			}
+			return false
+		},
+		UpdateFunc: func(e event.TypedUpdateEvent[client.Object]) bool {
+			return false
+		},
+		GenericFunc: func(e event.TypedGenericEvent[client.Object]) bool {
+			return false
+		},
+	}
+	return ctrl.NewControllerManagedBy(mgr).
+		For(&apiextensionsv1.CustomResourceDefinition{}, builder.WithPredicates(crdPredicate)).
+		Complete(r)
+}

controllers/util/k8sutil.go

@@ -11,6 +11,7 @@ import (
 	ocsv1 "github.com/red-hat-storage/ocs-operator/api/v4/v1"
 	corev1 "k8s.io/api/core/v1"
 	storagev1 "k8s.io/api/storage/v1"
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/types"
 	"sigs.k8s.io/controller-runtime/pkg/client"
@@ -44,6 +45,8 @@ const (
 	OwnerUIDIndexName = "ownerUID"
 )
 
+var CRDList []string
+
 // GetWatchNamespace returns the namespace the operator should be watching for changes
 func GetWatchNamespace() (string, error) {
 	ns, found := os.LookupEnv(WatchNamespaceEnvVar)
@@ -149,3 +152,16 @@ func GenerateNameForNonResilientCephBlockPoolSC(initData *ocsv1.StorageCluster)
 	}
 	return fmt.Sprintf("%s-ceph-non-resilient-rbd", initData.Name)
 }
+
+func MapCRDAvailability(ctx context.Context, clnt client.Client, crdNames ...string) (map[string]bool, error) {
+	crdExist := map[string]bool{}
+	for _, crdName := range crdNames {
+		crd := &apiextensionsv1.CustomResourceDefinition{}
+		crd.Name = crdName
+		if err := clnt.Get(ctx, client.ObjectKeyFromObject(crd), crd); client.IgnoreNotFound(err) != nil {
+			return nil, fmt.Errorf("error getting CRD, %v", err)
+		}
+		crdExist[crdName] = crd.UID != ""
+	}
+	return crdExist, nil
+}

main.go

@@ -57,6 +57,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 	metrics "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 
+	"github.com/red-hat-storage/ocs-operator/v4/controllers/crd"
 	"github.com/red-hat-storage/ocs-operator/v4/controllers/ocsinitialization"
 	"github.com/red-hat-storage/ocs-operator/v4/controllers/platform"
 	"github.com/red-hat-storage/ocs-operator/v4/controllers/storagecluster"
@@ -252,6 +253,22 @@ func main() {
 		os.Exit(1)
 	}
 
+	availCrds, err := util.MapCRDAvailability(context.Background(), apiClient, util.CRDList...)
+	if err != nil {
+		setupLog.Error(err, "Unable to get CRD")
+		os.Exit(1)
+	}
+	if len(util.CRDList) > 0 {
+		if err = (&crd.CustomResourceDefinitionReconciler{
+			Client:        mgr.GetClient(),
+			Log:           ctrl.Log.WithName("controllers").WithName("CustomResourceDefinitionReconciler"),
+			AvailableCrds: availCrds,
+		}).SetupWithManager(mgr); err != nil {
+			setupLog.Error(err, "unable to create controller", "controller", "CustomResourceDefinitionReconciler")
+			os.Exit(1)
+		}
+	}
+
 	// Set OperatorCondition Upgradeable to True
 	// We have to at least default the condition to True or
 	// OLM will use the Readiness condition via our readiness probe instead: