Merge pull request #658 from ClusterHQ/use-snapshot-information-46

Expand the remote volume manager interface so it can convey information about the snapshots that exist for the filesystems it manages.

flocker/volume/_ipc.py

@@ -17,13 +17,27 @@
 
 from zope.interface import Interface, implementer
 
+from twisted.internet.defer import succeed
+
 from .service import DEFAULT_CONFIG_PATH
+from .filesystems.zfs import Snapshot
 
 
 class IRemoteVolumeManager(Interface):
     """
     A remote volume manager with which one can communicate somehow.
     """
+    def snapshots(volume):
+        """
+        Retrieve a list of the snapshots which exist for the given volume.
+
+        :param Volume volume: The volume for which to retrieve snapshots.
+
+        :return: A ``Deferred`` that fires with a ``list`` of ``Snapshot``
+            instances giving the snapshot information.  The snapshots are
+            ordered from oldest to newest.
+        """
+
     def receive(volume):
         """
         Context manager that returns a file-like object to which a volume's
@@ -63,6 +77,24 @@ def __init__(self, destination, config_path=DEFAULT_CONFIG_PATH):
         self._destination = destination
         self._config_path = config_path
 
+    def snapshots(self, volume):
+        """
+        Run ``flocker-volume snapshots`` on the destination and parse the
+        output into a ``list`` of ``Snapshot`` instances.
+        """
+        data = self._destination.get_output(
+            [b"flocker-volume",
+             b"--config", self._config_path.path,
+             b"snapshots",
+             volume.uuid.encode("ascii"),
+             volume.name.encode("ascii")]
+        )
+        return succeed([
+            Snapshot(name=name)
+            for name
+            in data.splitlines()
+        ])
+
     def receive(self, volume):
         return self._destination.run([b"flocker-volume",
                                       b"--config", self._config_path.path,
@@ -91,6 +123,12 @@ def __init__(self, service):
         """
         self._service = service
 
+    def snapshots(self, volume):
+        """
+        Interrogate the volume's filesystem for its snapshots.
+        """
+        return volume.get_filesystem().snapshots()
+
     @contextmanager
     def receive(self, volume):
         input_file = BytesIO()

flocker/volume/functional/test_script.py

@@ -79,3 +79,26 @@ def test_no_permission(self):
         self.assertEqual(result,
                          b"Writing config file %s failed: Permission denied\n"
                          % (config.path,))
+
+
+class FlockerVolumeSnapshotsTests(TestCase):
+    """
+    Tests for ``flocker-volume snapshots``.
+    """
+    @_require_installed
+    def test_snapshots(self):
+        """
+        The output of ``flocker-volume snapshots`` is the name of each snapshot
+        that exists for the identified filesystem, one per line.
+        """
+        pool_name = create_zfs_pool(self)
+        dataset = pool_name + b"/myuuid.myfilesystem"
+        check_output([b"zfs", b"create", b"-p", dataset])
+        check_output([b"zfs", b"snapshot", dataset + b"@somesnapshot"])
+        check_output([b"zfs", b"snapshot", dataset + b"@lastsnapshot"])
+        config_path = FilePath(self.mktemp())
+        snapshots = run(
+            b"--config", config_path.path,
+            b"--pool", pool_name,
+            b"snapshots", b"myuuid", b"myfilesystem")
+        self.assertEqual(snapshots, b"somesnapshot\nlastsnapshot\n")

flocker/volume/script.py

@@ -12,7 +12,7 @@
 
 from .service import (
     DEFAULT_CONFIG_PATH, FLOCKER_MOUNTPOINT, FLOCKER_POOL,
-    VolumeScript, ICommandLineVolumeScript
+    Volume, VolumeScript, ICommandLineVolumeScript
     )
 from ..common.script import (
     flocker_standard_options, FlockerScriptRunner
@@ -60,6 +60,37 @@ def postOptions(self):
     return cls
 
 
+class _SnapshotsSubcommandOptions(Options):
+    """
+    Command line options for ``flocker-volume snapshots``.
+    """
+
+    longdesc = """List local snapshots of a particular volume.
+
+    Parameters:
+
+    * owner-uuid: The UUID of the volume manager that owns the volume.
+
+    * name: The name of the volume.
+    """
+
+    def parseArgs(self, uuid, name):
+        self["uuid"] = uuid.decode("ascii")
+        self["name"] = name.decode("ascii")
+
+    def run(self, service):
+        volume = Volume(uuid=self["uuid"], name=self["name"], service=service)
+        filesystem = volume.get_filesystem()
+        snapshots = filesystem.snapshots()
+
+        def got_snapshots(snapshots):
+            for snapshot in snapshots:
+                sys.stdout.write(snapshot.name + b"\n")
+
+        snapshots.addCallback(got_snapshots)
+        return snapshots
+
+
 class _ReceiveSubcommandOptions(Options):
     """Command line options for ``flocker-volume receive``."""
 
@@ -140,6 +171,8 @@ class VolumeOptions(Options):
     synopsis = "Usage: flocker-volume [OPTIONS]"
 
     subCommands = [
+        ["snapshots", None, _SnapshotsSubcommandOptions,
+         "List snapshots for a volume."],
         ["receive", None, _ReceiveSubcommandOptions,
          "Receive a remotely pushed volume."],
         ["acquire", None, _AcquireSubcommandOptions,

flocker/volume/test/test_ipc.py

@@ -13,6 +13,7 @@
 from twisted.trial.unittest import TestCase
 
 from ..service import VolumeService, Volume, DEFAULT_CONFIG_PATH
+from ..filesystems.zfs import Snapshot
 from ..filesystems.memory import FilesystemStoragePool
 from .._ipc import (
     IRemoteVolumeManager, RemoteVolumeManager, LocalVolumeManager)
@@ -211,65 +212,85 @@ class LocalVolumeManagerInterfaceTests(
     """
     Tests for ``LocalVolumeManager`` as a ``IRemoteVolumeManager``.
     """
+    def test_snapshots(self):
+        """
+        ``LocalVolumeManager.snapshots`` returns a ``Deferred`` that fires with
+        ``[]`` because ``DirectoryFilesystem`` does not support snapshots.
+        """
+        pair = create_local_servicepair(self)
+        volume = self.successResultOf(pair.from_service.create(u"myvolume"))
+        self.assertEqual(
+            [], self.successResultOf(pair.remote.snapshots(volume)))
 
 
 class RemoteVolumeManagerTests(TestCase):
     """
     Tests for ``RemoteVolumeManager``.
     """
+    def setUp(self):
+        self.pool = FilesystemStoragePool(FilePath(self.mktemp()))
+        self.service = VolumeService(
+            FilePath(self.mktemp()), self.pool, reactor=Clock())
+        self.service.startService()
+        self.volume = self.successResultOf(self.service.create(u"myvolume"))
+
+    def test_snapshots_destination_run(self):
+        """
+        ``RemoteVolumeManager.snapshots`` calls ``flocker-volume`` remotely
+        with the ``snapshots`` sub-command.
+        """
+        node = FakeNode([b"abc\ndef\n"])
+
+        remote = RemoteVolumeManager(node, FilePath(b"/path/to/json"))
+        snapshots = self.successResultOf(remote.snapshots(self.volume))
+        self.assertEqual(node.remote_command,
+                         [b"flocker-volume", b"--config", b"/path/to/json",
+                          b"snapshots", self.volume.uuid.encode("ascii"),
+                          b"myvolume"])
+        self.assertEqual(
+            [Snapshot(name="abc"), Snapshot(name="def")], snapshots)
+
     def test_receive_destination_run(self):
         """
         Receiving calls ``flocker-volume`` remotely with ``receive`` command.
         """
-        pool = FilesystemStoragePool(FilePath(self.mktemp()))
-        service = VolumeService(FilePath(self.mktemp()), pool, reactor=Clock())
-        service.startService()
-        volume = self.successResultOf(service.create(u"myvolume"))
         node = FakeNode()
 
         remote = RemoteVolumeManager(node, FilePath(b"/path/to/json"))
-        with remote.receive(volume):
+        with remote.receive(self.volume):
             pass
         self.assertEqual(node.remote_command,
                          [b"flocker-volume", b"--config", b"/path/to/json",
-                          b"receive", volume.uuid.encode("ascii"),
+                          b"receive", self.volume.uuid.encode("ascii"),
                           b"myvolume"])
 
     def test_receive_default_config(self):
         """
         ``RemoteVolumeManager`` by default calls ``flocker-volume`` with
         default config path.
         """
-        pool = FilesystemStoragePool(FilePath(self.mktemp()))
-        service = VolumeService(FilePath(self.mktemp()), pool, reactor=Clock())
-        service.startService()
-        volume = self.successResultOf(service.create(u"myvolume"))
         node = FakeNode()
 
         remote = RemoteVolumeManager(node)
-        with remote.receive(volume):
+        with remote.receive(self.volume):
             pass
         self.assertEqual(node.remote_command,
                          [b"flocker-volume", b"--config",
                           DEFAULT_CONFIG_PATH.path,
-                          b"receive", volume.uuid.encode("ascii"),
+                          b"receive", self.volume.uuid.encode("ascii"),
                           b"myvolume"])
 
     def test_acquire_destination_run(self):
         """
         ``RemoteVolumeManager.acquire()`` calls ``flocker-volume`` remotely
         with ``acquire`` command.
         """
-        pool = FilesystemStoragePool(FilePath(self.mktemp()))
-        service = VolumeService(FilePath(self.mktemp()), pool, reactor=Clock())
-        service.startService()
-        volume = self.successResultOf(service.create(u"myvolume"))
         node = FakeNode([b"remoteuuid"])
 
         remote = RemoteVolumeManager(node, FilePath(b"/path/to/json"))
-        remote.acquire(volume)
+        remote.acquire(self.volume)
 
         self.assertEqual(node.remote_command,
                          [b"flocker-volume", b"--config", b"/path/to/json",
-                          b"acquire", volume.uuid.encode("ascii"),
+                          b"acquire", self.volume.uuid.encode("ascii"),
                           b"myvolume"])