disk: support automatic name generation for swap devices

This commit adds support for automatic geneation of names for
an lv swap devices. This saves the users of advanced blueprints
some typing.

pkg/disk/lvm.go

@@ -110,12 +110,15 @@ func (vg *LVMVolumeGroup) CreateLogicalVolume(lvName string, size uint64, payloa
 
 	if lvName == "" {
 		// generate a name based on the payload's mountpoint
-		mntble, ok := payload.(Mountable)
-		if !ok {
-			return nil, fmt.Errorf("could not create logical volume: no name provided and payload is not mountable")
+		switch ent := payload.(type) {
+		case Mountable:
+			lvName = ent.GetMountpoint()
+		case *Swap:
+			lvName = "swap"
+		default:
+			return nil, fmt.Errorf("could not create logical volume: no name provided and payload %T is not mountable or swap", payload)
 		}
-		mountpoint := mntble.GetMountpoint()
-		autoName, err := vg.genLVName(mountpoint)
+		autoName, err := vg.genLVName(lvName)
 		if err != nil {
 			return nil, err
 		}

pkg/disk/lvm_test.go

@@ -39,6 +39,29 @@ func TestLVMVCreateMountpoint(t *testing.T) {
 	assert.Error(err)
 }
 
+func TestLVMVCreateLogicalVolumeSwap(t *testing.T) {
+	vg := &LVMVolumeGroup{
+		Name:        "root",
+		Description: "root volume group",
+	}
+	swap := &Swap{}
+	lv, err := vg.CreateLogicalVolume("", 12345, swap)
+	assert.NoError(t, err)
+	assert.Equal(t, "swaplv", lv.Name)
+	// one more
+	lv2, err := vg.CreateLogicalVolume("", 12345, swap)
+	assert.NoError(t, err)
+	assert.Equal(t, "swaplv00", lv2.Name)
+}
+
+func TestLVMVCreateLogicalVolumeWrongType(t *testing.T) {
+	vg := &LVMVolumeGroup{
+		Name: "root",
+	}
+	_, err := vg.CreateLogicalVolume("", 12345, &LUKSContainer{})
+	assert.EqualError(t, err, `could not create logical volume: no name provided and payload *disk.LUKSContainer is not mountable or swap`)
+}
+
 func TestImplementsInterfacesCompileTimeCheckLVM(t *testing.T) {
 	var _ = Container(&LVMVolumeGroup{})
 	var _ = Sizeable(&LVMLogicalVolume{})