osbuild2: new GenDeviceFinishStages method

This should be called at the end of the pipeline that creates an
image, to add stages that are needed to finish up the image.
Currently the only stage that will be added is the `lvm2.metadata`
stage in the case the partition layout contains LVM2.

Co-Authored-By: Achilleas Koutsou <achilleas@koutsou.net>

internal/osbuild2/device.go

@@ -85,6 +85,37 @@ func GenDeviceCreationStages(pt *disk.PartitionTable, filename string) []*Stage
 	return stages
 }
 
+func GenDeviceFinishStages(pt *disk.PartitionTable, filename string) []*Stage {
+	stages := make([]*Stage, 0)
+
+	genStages := func(e disk.Entity, path []disk.Entity) error {
+
+		switch ent := e.(type) {
+		case *disk.LVMVolumeGroup:
+			// do not include us when getting the devices
+			stageDevices, lastName := getDevices(path[:len(path)-1], filename)
+
+			// "org.osbuild.lvm2.metadata" expects a "device" to rename the VG,
+			// thus rename the last device to "device"
+			lastDevice := stageDevices[lastName]
+			delete(stageDevices, lastName)
+			stageDevices["device"] = lastDevice
+
+			stage := NewLVM2MetadataStage(
+				&LVM2MetadataStageOptions{
+					VGName: ent.Name,
+				}, stageDevices)
+
+			stages = append(stages, stage)
+		}
+
+		return nil
+	}
+
+	_ = pt.ForEachEntity(genStages)
+	return stages
+}
+
 func deviceName(p disk.Entity) string {
 	if p == nil {
 		panic("device is nil; this is a programming error")

internal/osbuild2/device_test.go

@@ -71,3 +71,46 @@ func TestGenDeviceCreationStages(t *testing.T) {
 	assert.Equal(parent.Type, "org.osbuild.loopback")
 
 }
+
+func TestGenDeviceFinishStages(t *testing.T) {
+	assert := assert.New(t)
+
+	// math/rand is good enough in this case
+	/* #nosec G404 */
+	rng := rand.New(rand.NewSource(13))
+
+	luks_lvm := testPartitionTables["luks+lvm"]
+
+	pt, err := disk.NewPartitionTable(&luks_lvm, []blueprint.FilesystemCustomization{}, 0, rng)
+	assert.NoError(err)
+
+	stages := GenDeviceFinishStages(pt, "image.raw")
+
+	// we should have one stage
+	assert.Equal(1, len(stages))
+
+	// it should be a "org.osbuild.lvm2.metadata"
+	lvm := stages[0]
+	assert.Equal("org.osbuild.lvm2.metadata", lvm.Type)
+
+	// it should have two devices
+	assert.Equal(2, len(lvm.Devices))
+
+	// this is the target one, which should be the luks one
+	device, ok := lvm.Devices["device"]
+	assert.True(ok, "Need device called `device`")
+	assert.Equal("org.osbuild.luks2", device.Type)
+	assert.NotEmpty(device.Parent, "Need a parent device for LUKS on loopback")
+
+	luksOptions, ok := device.Options.(*LUKS2DeviceOptions)
+	assert.True(ok, "Need LUKS2DeviceOptions for luks device")
+	assert.Equal("osbuild", luksOptions.Passphrase)
+
+	parent, ok := lvm.Devices[device.Parent]
+	assert.True(ok, "Need device called `device`")
+	assert.Equal("org.osbuild.loopback", parent.Type)
+
+	opts, ok := lvm.Options.(*LVM2MetadataStageOptions)
+	assert.True(ok, "Need LVM2MetadataStageOptions for org.osbuild.lvm2.metadata")
+	assert.Equal("root", opts.VGName)
+}