Fix backward incompatibility regression.

The introduction of argo-rollouts introduced a call to the new
traffic-manager function `GetKnownWorkloadKinds` from the user client,
and a client connecting to older traffic-managers that don't have this
method would therefore fail with an error.

This commit checks if the returned error has code `Unimplemented`, and
if so, assumes the default set of workload kinds.

Signed-off-by: Thomas Hallgren <thomas@tada.se>

pkg/client/userd/daemon/grpc.go

@@ -345,7 +345,18 @@ func (s *service) List(c context.Context, lr *rpc.ListRequest) (result *rpc.Work
 func (s *service) GetKnownWorkloadKinds(ctx context.Context, _ *empty.Empty) (result *manager.KnownWorkloadKinds, err error) {
 	err = s.WithSession(ctx, "GetKnownWorkloadKinds", func(ctx context.Context, session userd.Session) error {
 		result, err = session.ManagerClient().GetKnownWorkloadKinds(ctx, session.SessionInfo())
-		return err
+		if err != nil {
+			if status.Code(err) != codes.Unimplemented {
+				return err
+			}
+			// Talking to an older traffic-manager, use legacy default types
+			result = &manager.KnownWorkloadKinds{Kinds: []manager.WorkloadInfo_Kind{
+				manager.WorkloadInfo_DEPLOYMENT,
+				manager.WorkloadInfo_REPLICASET,
+				manager.WorkloadInfo_STATEFULSET,
+			}}
+		}
+		return nil
 	})
 	return result, err
 }

pkg/client/userd/trafficmgr/session.go

@@ -441,7 +441,15 @@ func connectMgr(
 
 	knownWorkloadKinds, err := mClient.GetKnownWorkloadKinds(ctx, si)
 	if err != nil {
-		return nil, fmt.Errorf("failed to get known workload kinds: %w", err)
+		if status.Code(err) != codes.Unimplemented {
+			return nil, fmt.Errorf("failed to get known workload kinds: %w", err)
+		}
+		// Talking to an older traffic-manager, use legacy default types
+		knownWorkloadKinds = &manager.KnownWorkloadKinds{Kinds: []manager.WorkloadInfo_Kind{
+			manager.WorkloadInfo_DEPLOYMENT,
+			manager.WorkloadInfo_REPLICASET,
+			manager.WorkloadInfo_STATEFULSET,
+		}}
 	}
 
 	sess := &session{