govc: add vm.migrate -net flag

govc/test/vm.bats

@@ -959,6 +959,15 @@ load test_helper
 
   run govc object.collect -s "vm/new-folder/$vm" parent
   assert_success
+
+  run govc vm.info -r "$vm"
+  assert_matches "Network: +DC0_DVPG0"
+
+  run govc vm.migrate -host "$host0" -net "VM Network" "$vm"
+  assert_success
+
+  run govc vm.info -r "$vm"
+  assert_matches "Network: +VM Network"
 }
 
 @test "object name with slash" {

govc/vm/migrate.go

@@ -32,6 +32,7 @@ type migrate struct {
 	*flags.ResourcePoolFlag
 	*flags.HostSystemFlag
 	*flags.DatastoreFlag
+	*flags.NetworkFlag
 	*flags.VirtualMachineFlag
 
 	priority types.VirtualMachineMovePriority
@@ -58,6 +59,9 @@ func (cmd *migrate) Register(ctx context.Context, f *flag.FlagSet) {
 	cmd.DatastoreFlag, ctx = flags.NewDatastoreFlag(ctx)
 	cmd.DatastoreFlag.Register(ctx, f)
 
+	cmd.NetworkFlag, ctx = flags.NewNetworkFlag(ctx)
+	cmd.NetworkFlag.Register(ctx, f)
+
 	f.StringVar((*string)(&cmd.priority), "priority", string(types.VirtualMachineMovePriorityDefaultPriority), "The task priority")
 }
 
@@ -77,6 +81,9 @@ func (cmd *migrate) Process(ctx context.Context) error {
 	if err := cmd.DatastoreFlag.Process(ctx); err != nil {
 		return err
 	}
+	if err := cmd.NetworkFlag.Process(ctx); err != nil {
+		return err
+	}
 
 	return nil
 }
@@ -95,7 +102,32 @@ Examples:
 }
 
 func (cmd *migrate) relocate(ctx context.Context, vm *object.VirtualMachine) error {
-	task, err := vm.Relocate(ctx, cmd.spec, cmd.priority)
+	spec := cmd.spec
+
+	if cmd.NetworkFlag.IsSet() {
+		dev, err := cmd.NetworkFlag.Device()
+		if err != nil {
+			return err
+		}
+
+		devices, err := vm.Device(ctx)
+		if err != nil {
+			return err
+		}
+
+		net := devices.SelectByType((*types.VirtualEthernetCard)(nil))
+		if len(net) != 1 {
+			return fmt.Errorf("-net specified, but %s has %d nics", vm.Name(), len(net))
+		}
+		cmd.NetworkFlag.Change(net[0], dev)
+
+		spec.DeviceChange = append(spec.DeviceChange, &types.VirtualDeviceConfigSpec{
+			Device:    net[0],
+			Operation: types.VirtualDeviceConfigSpecOperationEdit,
+		})
+	}
+
+	task, err := vm.Relocate(ctx, spec, cmd.priority)
 	if err != nil {
 		return err
 	}

simulator/virtual_machine.go

@@ -2345,6 +2345,11 @@ func (vm *VirtualMachine) RelocateVMTask(ctx *Context, req *types.RelocateVM_Tas
 			})
 		}
 
+		cspec := &types.VirtualMachineConfigSpec{DeviceChange: req.Spec.DeviceChange}
+		if err := vm.configureDevices(ctx, cspec); err != nil {
+			return nil, err
+		}
+
 		ctx.postEvent(&types.VmMigratedEvent{
 			VmEvent:          vm.event(),
 			SourceHost:       *ctx.Map.Get(*vm.Runtime.Host).(*HostSystem).eventArgument(),