Ensure getPrimaryInterfaceID not panic when network interfaces for Azure VMSS are null

Author: feiskyer

staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss.go

@@ -534,17 +534,21 @@ func (ss *scaleSet) GetPrivateIPsByNodeName(nodeName string) ([]string, error) {
 
 // This returns the full identifier of the primary NIC for the given VM.
 func (ss *scaleSet) getPrimaryInterfaceID(machine compute.VirtualMachineScaleSetVM) (string, error) {
+	if machine.NetworkProfile == nil || machine.NetworkProfile.NetworkInterfaces == nil {
+		return "", fmt.Errorf("failed to find the network interfaces for vm %s", to.String(machine.Name))
+	}
+
 	if len(*machine.NetworkProfile.NetworkInterfaces) == 1 {
 		return *(*machine.NetworkProfile.NetworkInterfaces)[0].ID, nil
 	}
 
 	for _, ref := range *machine.NetworkProfile.NetworkInterfaces {
-		if *ref.Primary {
+		if to.Bool(ref.Primary) {
 			return *ref.ID, nil
 		}
 	}
 
-	return "", fmt.Errorf("failed to find a primary nic for the vm. vmname=%q", *machine.Name)
+	return "", fmt.Errorf("failed to find a primary nic for the vm. vmname=%q", to.String(machine.Name))
 }
 
 // getVmssMachineID returns the full identifier of a vmss virtual machine.

staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss_test.go

@@ -949,6 +949,11 @@ func TestGetPrimaryInterfaceID(t *testing.T) {
 			},
 			expectedErr: fmt.Errorf("failed to find a primary nic for the vm. vmname=\"vm\""),
 		},
+		{
+			description:       "GetPrimaryInterfaceID should report an error if there's no network interface on the VMSS VM",
+			existedInterfaces: []compute.NetworkInterfaceReference{},
+			expectedErr:       fmt.Errorf("failed to find the network interfaces for vm vm"),
+		},
 	}
 
 	for _, test := range testCases {
@@ -963,6 +968,9 @@ func TestGetPrimaryInterfaceID(t *testing.T) {
 				},
 			},
 		}
+		if len(test.existedInterfaces) == 0 {
+			vm.VirtualMachineScaleSetVMProperties.NetworkProfile = nil
+		}
 
 		id, err := ss.getPrimaryInterfaceID(vm)
 		assert.Equal(t, test.expectedErr, err, test.description+", but an error occurs")