fix: auto-register nodes on ControllerPublishVolume

With attachRequired=true, kubelet calls ControllerPublishVolume before
the node plugin registers via NodeGetInfo. The controller was rejecting
these with NotFound, preventing any volume from mounting.

Instead of rejecting unknown nodes, register them on first publish.
The kubelet guarantees the node exists — it's the one making the call.

Author: fenio

pkg/driver/controller.go

@@ -678,10 +678,11 @@ func (s *ControllerService) ControllerPublishVolume(_ context.Context, req *csi.
 		return nil, status.Error(codes.InvalidArgument, "Volume capability is required")
 	}
 
-	// Validate node exists in registry
-	// Per CSI spec: return NotFound if node doesn't exist
-	if s.nodeRegistry != nil && !s.nodeRegistry.IsRegistered(nodeID) {
-		return nil, status.Errorf(codes.NotFound, "node %s not found", nodeID)
+	// Register node on first publish — with attachRequired=true, ControllerPublishVolume
+	// is called before the node plugin has had a chance to register via NodeGetInfo.
+	// The kubelet guarantees the node exists (it's the one making the call).
+	if s.nodeRegistry != nil {
+		s.nodeRegistry.Register(nodeID)
 	}
 
 	// Check if volume is already published to this node with different readonly state

pkg/driver/controller_test.go

@@ -518,7 +518,7 @@ func TestControllerPublishVolume(t *testing.T) {
 			wantCode: codes.InvalidArgument,
 		},
 		{
-			name: "node not found",
+			name: "unknown node auto-registers on publish",
 			req: &csi.ControllerPublishVolumeRequest{
 				VolumeId: volumeID,
 				NodeId:   "unknown-node",
@@ -528,9 +528,8 @@ func TestControllerPublishVolume(t *testing.T) {
 					},
 				},
 			},
-			nodeReg:  NewNodeRegistry(),
-			wantErr:  true,
-			wantCode: codes.NotFound,
+			nodeReg: NewNodeRegistry(),
+			wantErr: false,
 		},
 	}