add possibility to choose whether snapshot base volume or copy

libvirt volume resource now has key base_volume_copy which controls
whether to invoke StorageVolCreateXML (defualt) or StorageVolCreateXMLFrom

Author: cyril-s

libvirt/resource_libvirt_volume.go

@@ -58,6 +58,12 @@ func resourceLibvirtVolume() *schema.Resource {
 				Optional: true,
 				ForceNew: true,
 			},
+			"base_volume_copy": {
+				Type:     schema.TypeBool,
+				Optional: true,
+				ForceNew: true,
+				Default:  false,
+			},
 			"xml": {
 				Type:     schema.TypeList,
 				Optional: true,
@@ -118,6 +124,8 @@ func resourceLibvirtVolumeCreate(d *schema.ResourceData, meta interface{}) error
 		volumeDef.Target.Format.Type = givenFormat.(string)
 	}
 
+	var baseVolume *libvirt.StorageVol
+
 	// an source image was given, this mean we can't choose size
 	if source, ok := d.GetOk("source"); ok {
 		// source and size conflict
@@ -167,7 +175,6 @@ func resourceLibvirtVolumeCreate(d *schema.ResourceData, meta interface{}) error
 
 		//first handle whether it has a backing image
 		// backing images can be specified by either (id), or by (name, pool)
-		var baseVolume *libvirt.StorageVol
 		if baseVolumeID, ok := d.GetOk("base_volume_id"); ok {
 			if _, ok := d.GetOk("base_volume_name"); ok {
 				return fmt.Errorf("'base_volume_name' can't be specified when also 'base_volume_id' is given")
@@ -192,7 +199,7 @@ func resourceLibvirtVolumeCreate(d *schema.ResourceData, meta interface{}) error
 			}
 		}
 
-		if baseVolume != nil {
+		if !d.Get("base_volume_copy").(bool) && baseVolume != nil {
 			backingStoreFragmentDef, err := newDefBackingStoreFromLibvirt(baseVolume)
 			if err != nil {
 				return fmt.Errorf("Could not retrieve backing store definition: %s", err.Error())
@@ -214,6 +221,8 @@ func resourceLibvirtVolumeCreate(d *schema.ResourceData, meta interface{}) error
 				return fmt.Errorf("When 'size' is specified, it shouldn't be smaller than the backing store specified with 'base_volume_id' or 'base_volume_name/base_volume_pool'")
 			}
 			volumeDef.BackingStore = &backingStoreFragmentDef
+		} else if d.Get("base_volume_copy").(bool) && baseVolume == nil {
+			return fmt.Errorf("Can't find base volume to copy to '%s'", d.Get("name").(string))
 		}
 	}
 
@@ -229,7 +238,12 @@ func resourceLibvirtVolumeCreate(d *schema.ResourceData, meta interface{}) error
 	}
 
 	// create the volume
-	volume, err := pool.StorageVolCreateXML(data, 0)
+	var volume *libvirt.StorageVol
+	if d.Get("base_volume_copy").(bool) {
+		volume, err = pool.StorageVolCreateXMLFrom(data, baseVolume, 0)
+	} else {
+		volume, err = pool.StorageVolCreateXML(data, 0)
+	}
 	if err != nil {
 		return fmt.Errorf("Error creating libvirt volume: %s", err)
 	}

libvirt/resource_libvirt_volume_test.go

@@ -92,6 +92,33 @@ func testAccCheckLibvirtVolumeIsBackingStore(name string, volume *libvirt.Storag
 	}
 }
 
+func testAccCheckLibvirtVolumeIsNotBackingStore(name string, volume *libvirt.StorageVol) resource.TestCheckFunc {
+	return func(state *terraform.State) error {
+		virConn := testAccProvider.Meta().(*Client).libvirt
+
+		vol, err := getVolumeFromTerraformState(name, state, *virConn)
+		if err != nil {
+			return err
+		}
+
+		volXMLDesc, err := vol.GetXMLDesc(0)
+		if err != nil {
+			return fmt.Errorf("Error retrieving libvirt volume XML description: %s", err)
+		}
+
+		volumeDef := newDefVolume()
+		err = xml.Unmarshal([]byte(volXMLDesc), &volumeDef)
+		if err != nil {
+			return fmt.Errorf("Error reading libvirt volume XML description: %s", err)
+		}
+		if volumeDef.BackingStore != nil {
+			return fmt.Errorf("FAIL: the volume was not supposed to be a backingstore, but it is")
+		}
+
+		return nil
+	}
+}
+
 func TestAccLibvirtVolume_Basic(t *testing.T) {
 	var volume libvirt.StorageVol
 	randomVolumeResource := acctest.RandStringFromCharSet(10, acctest.CharSetAlpha)
@@ -206,6 +233,90 @@ func TestAccLibvirtVolume_BackingStoreTestByName(t *testing.T) {
 	})
 }
 
+func TestAccLibvirtVolume_BackingStoreCopyDir(t *testing.T) {
+	var volume libvirt.StorageVol
+	var volume2 libvirt.StorageVol
+	random := acctest.RandStringFromCharSet(10, acctest.CharSetAlpha)
+	randomPoolPath := "/tmp/terraform-provider-libvirt-pool-" + random
+	// for qcow2 file images regardless of user specified size, the final size will
+	// be the same as the backing image's size. This is so because libvirt
+	// invokes qemu-img create followed by qemu-img convert for StorageVolCreateXMLFrom.
+	// This behavior can be tested like this:
+	// $ qemu-img create -f qcow2 test.qcow2 1024K
+	// $ qemu-img info test.qcow2
+	// $ qemu-img create -f qcow2 test-copy.qcow2 2048K
+	// $ qemu-img info test-copy.qcow2
+	// $ qemu-img convert -f qcow2 -O qcow2 test.qcow2 test-copy.qcow2
+	// $ qemu-img info test-copy.qcow2
+	resource.Test(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		CheckDestroy: resource.ComposeAggregateTestCheckFunc(
+			testAccCheckLibvirtVolumeDestroy,
+			testAccCheckLibvirtPoolDestroy,
+		),
+		Steps: []resource.TestStep{
+			{
+				Config: fmt.Sprintf(`
+                resource "libvirt_pool" "%s" {
+                    name = "%s"
+                    type = "dir"
+                    path = "%s"
+                }
+				resource "libvirt_volume" "backing-%s" {
+					name = "backing-%s"
+					size = 1000448
+                    pool = "${libvirt_pool.%s.name}"
+				}
+				resource "libvirt_volume" "%s" {
+					name = "%s"
+					base_volume_copy = true
+					base_volume_id = "${libvirt_volume.backing-%s.id}"
+                    pool = "${libvirt_pool.%s.name}"
+			        }
+				`, random, random, randomPoolPath, random, random, random, random, random, random, random),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckLibvirtVolumeExists("libvirt_volume.backing-"+random, &volume),
+					testAccCheckLibvirtVolumeIsNotBackingStore("libvirt_volume."+random, &volume2),
+				),
+			},
+		},
+	})
+}
+
+func TestAccLibvirtVolume_NoBackingStoreCopyError(t *testing.T) {
+	random := acctest.RandStringFromCharSet(10, acctest.CharSetAlpha)
+	randomPoolPath := "/tmp/terraform-provider-libvirt-pool-" + random
+	expectedError := regexp.MustCompile(fmt.Sprintf(
+		"Can't find base volume to copy to '%s'", random,
+	))
+	resource.Test(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		CheckDestroy: resource.ComposeAggregateTestCheckFunc(
+			testAccCheckLibvirtVolumeDestroy,
+			testAccCheckLibvirtPoolDestroy,
+		),
+		Steps: []resource.TestStep{
+			{
+				Config: fmt.Sprintf(`
+                resource "libvirt_pool" "%s" {
+                    name = "%s"
+                    type = "dir"
+                    path = "%s"
+                }
+				resource "libvirt_volume" "%s" {
+					name = "%s"
+					base_volume_copy = true
+                    pool = "${libvirt_pool.%s.name}"
+			        }
+				`, random, random, randomPoolPath, random, random, random),
+				ExpectError: expectedError,
+			},
+		},
+	})
+}
+
 // The destroy function should always handle the case where the resource might already be destroyed
 // (manually, for example). If the resource is already destroyed, this should not return an error.
 // This allows Terraform users to manually delete resources without breaking Terraform.

website/docs/r/volume.html.markdown

@@ -64,6 +64,11 @@ The following arguments are supported:
   volume is going to be searched inside of `pool`.
 * `base_volume_pool` - (Optional) The name of the storage pool containing the
   volume defined by `base_volume_name`.
+* `base_volume_copy` - (Optional) If set to `true`, [virStorageVolCreateXMLFrom]
+  is invoked rather than default [virStorageVolCreateXML] when creating from
+  base volume. This allows to create copies of volumes not associated with base
+  volumes in libvirt xml definitions, create copies (not snapshots) of lvm volumes
+  which also can be larger than the base volume, etc.
 
 ### Altering libvirt's generated volume XML definition
 
@@ -80,3 +85,7 @@ See the domain option with the same name for more information and examples.
 ## Attributes Reference
 
 * `id` - a unique identifier for the resource
+
+
+[virStorageVolCreateXMLFrom]: <https://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolCreateXMLFrom>
+[virStorageVolCreateXML]: <https://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolCreateXML>