fix a possible race condition by iso disk download

libvirt/cloudinit_def.go

@@ -191,9 +191,10 @@ func (ci *defCloudInit) createFiles() (string, error) {
 
 // Creates a new defCloudInit object starting from a ISO volume handled by
 // libvirt
-func newCloudInitDefFromRemoteISO(virConn *libvirt.Connect, id string) (defCloudInit, error) {
+func newCloudInitDefFromRemoteISO(virConn *libvirt.Connect, id string, client *Client) (defCloudInit, error) {
 	ci := defCloudInit{}
 
+	// get cloudinit volume from ID
 	key, err := getCloudInitVolumeKeyFromTerraformID(id)
 	if err != nil {
 		return ci, err
@@ -205,6 +206,33 @@ func newCloudInitDefFromRemoteISO(virConn *libvirt.Connect, id string) (defCloud
 	}
 	defer volume.Free()
 
+	// get poolname so we can lock pool after
+	volPool, err := volume.LookupPoolByVolume()
+	if err != nil {
+		return ci, fmt.Errorf("error retrieving pool for volume: %s", err)
+	}
+	defer volPool.Free()
+
+	volPoolName, err := volPool.GetName()
+	if err != nil {
+		return ci, fmt.Errorf("error retrieving pool name: %s", err)
+	}
+
+	pool, err := client.libvirt.LookupStoragePoolByName(volPoolName)
+	if err != nil {
+		return ci, fmt.Errorf("can't find storage pool '%s'", volPoolName)
+	}
+	defer pool.Free()
+
+	client.poolMutexKV.Lock(volPoolName)
+	defer client.poolMutexKV.Unlock(volPoolName)
+
+	// Refresh the pool of the volume so that libvirt knows it is
+	// not longer in use.
+	waitForSuccess("Error refreshing pool for volume", func() error {
+		return pool.Refresh(0)
+	})
+
 	err = ci.setCloudInitDiskNameFromExistingVol(volume)
 	if err != nil {
 		return ci, err
@@ -214,7 +242,9 @@ func newCloudInitDefFromRemoteISO(virConn *libvirt.Connect, id string) (defCloud
 	if err != nil {
 		return ci, err
 	}
-
+	// this function has stream.recv and volume/streams which are subject to race conditions.
+	// namely stream.recv can wait forever (IO.block) if for any reason it doesn't get right data to read
+	// https://libvirt.org/html/libvirt-libvirt-stream.html#virStreamRecv
 	isoFile, err := downloadISO(virConn, *volume)
 	if isoFile != nil {
 		defer os.Remove(isoFile.Name())

libvirt/resource_libvirt_cloud_init.go

@@ -82,11 +82,12 @@ func resourceCloudInitDiskCreate(d *schema.ResourceData, meta interface{}) error
 
 func resourceCloudInitDiskRead(d *schema.ResourceData, meta interface{}) error {
 	virConn := meta.(*Client).libvirt
+	client := meta.(*Client)
 	if virConn == nil {
 		return fmt.Errorf(LibVirtConIsNil)
 	}
 
-	ci, err := newCloudInitDefFromRemoteISO(virConn, d.Id())
+	ci, err := newCloudInitDefFromRemoteISO(virConn, d.Id(), client)
 	if err != nil {
 		return fmt.Errorf("error while retrieving remote ISO: %s", err)
 	}

libvirt/resource_libvirt_cloud_init_test.go

@@ -175,13 +175,13 @@ type Expected struct {
 func (expected *Expected) testAccCheckCloudInitDiskFilesContent(volumeName string, volume *libvirt.StorageVol) resource.TestCheckFunc {
 	return func(state *terraform.State) error {
 		virConn := testAccProvider.Meta().(*Client).libvirt
-
+		client := testAccProvider.Meta().(*Client)
 		rs, err := getResourceFromTerraformState(volumeName, state)
 		if err != nil {
 			return err
 		}
 
-		cloudInitDiskDef, err := newCloudInitDefFromRemoteISO(virConn, rs.Primary.ID)
+		cloudInitDiskDef, err := newCloudInitDefFromRemoteISO(virConn, rs.Primary.ID, client)
 
 		if cloudInitDiskDef.MetaData != expected.MetaData {
 			return fmt.Errorf("metadata '%s' content differs from expected Metadata %s", cloudInitDiskDef.MetaData, expected.MetaData)

libvirt/stream.go

@@ -19,8 +19,3 @@ func (sio *StreamIO) Read(p []byte) (int, error) {
 func (sio *StreamIO) Write(p []byte) (int, error) {
 	return sio.Stream.Send(p)
 }
-
-// Close closes the stream
-func (sio *StreamIO) Close() error {
-	return sio.Stream.Finish()
-}