Plugins: Support MT app registration (#113348)

pkg/services/apiserver/client/discovery.go

@@ -1,20 +1,29 @@
 package client
 
 import (
+	"context"
 	"fmt"
 	"strings"
+	"time"
 
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/rest"
 )
 
+var (
+	defaultPollInterval        = 500 * time.Millisecond
+	defaultAvailabilityTimeout = 30 * time.Second
+)
+
 type DiscoveryClient interface {
 	discovery.DiscoveryInterface
 	GetResourceForKind(gvk schema.GroupVersionKind) (schema.GroupVersionResource, error)
 	GetKindForResource(gvr schema.GroupVersionResource) (schema.GroupVersionKind, error)
 	GetPreferredVesion(gr schema.GroupResource) (schema.GroupVersionResource, schema.GroupVersionKind, error)
 	GetPreferredVersionForKind(gk schema.GroupKind) (schema.GroupVersionResource, schema.GroupVersionKind, error)
+	WaitForAvailability(ctx context.Context, gv schema.GroupVersion) error
 }
 
 type DiscoveryClientImpl struct {
@@ -134,3 +143,13 @@ func (d *DiscoveryClientImpl) GetPreferredVersionForKind(gk schema.GroupKind) (s
 	}
 	return schema.GroupVersionResource{}, schema.GroupVersionKind{}, fmt.Errorf("preferred version not found for kind %s in group %s", gk.Kind, gk.Group)
 }
+
+func (d *DiscoveryClientImpl) WaitForAvailability(ctx context.Context, gv schema.GroupVersion) error {
+	return wait.PollUntilContextTimeout(ctx, defaultPollInterval, defaultAvailabilityTimeout, true, func(ctx context.Context) (bool, error) {
+		_, err := d.ServerResourcesForGroupVersion(gv.String())
+		if err != nil {
+			return false, nil
+		}
+		return true, nil
+	})
+}