From 1a39ed9005306b0d3f42480b1fedf36b0b7834ff Mon Sep 17 00:00:00 2001
From: hackertron <jayadityagupta11@gmail.com>
Date: Mon, 23 Mar 2020 15:21:17 +0100
Subject: [PATCH] Support for nova-manage placement heal_allocations --cell

Closes-bug: #1868531

Change-Id: I98b3280583a6d12461d8aa52e5714d7606b84369
---
 doc/source/cli/nova-manage.rst                |  5 ++-
 nova/cmd/manage.py                            | 26 +++++++++++--
 nova/tests/functional/test_nova_manage.py     | 39 +++++++++++++++++++
 nova/tests/unit/cmd/test_manage.py            | 18 +++++++++
 ...-allocation-per-cell-9177b3e2161a632c.yaml |  4 ++
 5 files changed, 88 insertions(+), 4 deletions(-)
 create mode 100644 releasenotes/notes/register-allocation-per-cell-9177b3e2161a632c.yaml

diff --git a/doc/source/cli/nova-manage.rst b/doc/source/cli/nova-manage.rst
index a59eff8464d2..053de9917a8f 100644
--- a/doc/source/cli/nova-manage.rst
+++ b/doc/source/cli/nova-manage.rst
@@ -546,7 +546,7 @@ Placement
 
 .. _heal_allocations_cli:
 
-``nova-manage placement heal_allocations [--max-count <max_count>] [--verbose] [--skip-port-allocations] [--dry-run] [--instance <instance_uuid>]``
+``nova-manage placement heal_allocations [--max-count <max_count>] [--verbose] [--skip-port-allocations] [--dry-run] [--instance <instance_uuid>] [--cell <cell_uuid]``
     Iterates over non-cell0 cells looking for instances which do not have
     allocations in the Placement service and which are not undergoing a task
     state transition. For each instance found, allocations are created against
@@ -603,6 +603,9 @@ Placement
     ports for each instance can be avoided with this flag.
     *(Since 20.0.0 Train)*
 
+    Specify ``--cell`` to  process heal allocations within a specific cell.
+    This is mutually exclusive with the ``--instance`` option.
+
     This command requires that the
     :oslo.config:option:`api_database.connection` and
     :oslo.config:group:`placement` configuration options are set. Placement API
diff --git a/nova/cmd/manage.py b/nova/cmd/manage.py
index 48ba2cf6a36b..e47ea9333f7c 100644
--- a/nova/cmd/manage.py
+++ b/nova/cmd/manage.py
@@ -2089,7 +2089,8 @@ class PlacementCommands(object):
                'changes. The return code should be 4.')
     @args('--instance', metavar='<instance_uuid>', dest='instance_uuid',
           help='UUID of a specific instance to process. If specified '
-               '--max-count has no effect.')
+               '--max-count has no effect. '
+               'The --cell and --instance options are mutually exclusive.')
     @args('--skip-port-allocations', action='store_true',
           dest='skip_port_allocations', default=False,
           help='Skip the healing of the resource allocations of bound ports. '
@@ -2098,8 +2099,12 @@ class PlacementCommands(object):
                'not use such a feature then the performance impact of '
                'querying neutron ports for each instance can be avoided with '
                'this flag.')
+    @args('--cell', metavar='<cell_uuid>', dest='cell_uuid',
+          help='Heal allocations within a specific cell. '
+               'The --cell and --instance options are mutually exclusive.')
     def heal_allocations(self, max_count=None, verbose=False, dry_run=False,
-                         instance_uuid=None, skip_port_allocations=False):
+                         instance_uuid=None, skip_port_allocations=False,
+                         cell_uuid=None):
         """Heals instance allocations in the Placement service
 
         Return codes:
@@ -2116,7 +2121,6 @@ class PlacementCommands(object):
         * 127: Invalid input.
         """
         # NOTE(mriedem): Thoughts on ways to expand this:
-        # - allow passing a specific cell to heal
         # - allow filtering on enabled/disabled cells
         # - add a force option to force allocations for instances which have
         #   task_state is not None (would get complicated during a migration);
@@ -2134,6 +2138,13 @@ class PlacementCommands(object):
         if verbose:
             output = lambda msg: print(msg)
 
+        # If user has provided both cell and instance
+        # Throw an error
+        if instance_uuid and cell_uuid:
+            print(_('The --cell and --instance options '
+                    'are mutually exclusive.'))
+            return 127
+
         # TODO(mriedem): Rather than --max-count being both a total and batch
         # count, should we have separate options to be specific, i.e. --total
         # and --batch-size? Then --batch-size defaults to 50 and --total
@@ -2169,6 +2180,15 @@ class PlacementCommands(object):
                       '"nova-manage cell_v2 map_instances".' %
                       instance_uuid)
                 return 127
+        elif cell_uuid:
+            try:
+                # validate cell_uuid
+                cell = objects.CellMapping.get_by_uuid(ctxt, cell_uuid)
+                # create CellMappingList
+                cells = objects.CellMappingList(objects=[cell])
+            except exception.CellMappingNotFound:
+                print(_('Cell with uuid %s was not found.') % cell_uuid)
+                return 127
         else:
             cells = objects.CellMappingList.get_all(ctxt)
             if not cells:
diff --git a/nova/tests/functional/test_nova_manage.py b/nova/tests/functional/test_nova_manage.py
index 2634bde14eb5..213233ee2ede 100644
--- a/nova/tests/functional/test_nova_manage.py
+++ b/nova/tests/functional/test_nova_manage.py
@@ -746,6 +746,45 @@ class TestNovaManagePlacementHealAllocations(
         self.assertIn('Unable to find cell for instance %s, is it mapped?' %
                       server['id'], output)
 
+    def test_heal_allocations_specific_cell(self):
+        """Tests the case that a specific cell is processed and only that
+        cell even though there are two which require processing.
+        """
+        # Create one that we won't process.
+        server1, rp_uuid1 = self._boot_and_assert_no_allocations(
+            self.flavor, 'cell1')
+        # Create another that we will process specifically.
+        server2, rp_uuid2 = self._boot_and_assert_no_allocations(
+            self.flavor, 'cell2')
+
+        # Get Cell_id of cell2
+        cell2_id = self.cell_mappings['cell2'].uuid
+
+        # First do a dry run to make sure two instances need processing.
+        result = self.cli.heal_allocations(
+            max_count=2, verbose=True, dry_run=True)
+        # Nothing changed so the return code should be 4.
+        self.assertEqual(4, result, self.output.getvalue())
+        output = self.output.getvalue()
+        self.assertIn('Found 1 candidate instances', output)
+
+        # Now run with our specific cell and it should be the only one
+        # processed.
+        result = self.cli.heal_allocations(verbose=True,
+                                           cell_uuid=cell2_id)
+        output = self.output.getvalue()
+        self.assertEqual(0, result, self.output.getvalue())
+        self.assertIn('Found 1 candidate instances', output)
+        self.assertIn('Processed 1 instances.', output)
+
+        # Now run it again on the specific cell and it should be done.
+        result = self.cli.heal_allocations(
+            verbose=True, cell_uuid=cell2_id)
+        output = self.output.getvalue()
+        self.assertEqual(4, result, self.output.getvalue())
+        self.assertIn('Found 1 candidate instances', output)
+        self.assertIn('Processed 0 instances.', output)
+
 
 class TestNovaManagePlacementHealPortAllocations(
         test_servers.PortResourceRequestBasedSchedulingTestBase):
diff --git a/nova/tests/unit/cmd/test_manage.py b/nova/tests/unit/cmd/test_manage.py
index 8f70352d4bfa..c66afc2888de 100644
--- a/nova/tests/unit/cmd/test_manage.py
+++ b/nova/tests/unit/cmd/test_manage.py
@@ -2346,6 +2346,24 @@ class TestNovaManagePlacement(test.NoDBTestCase):
         self.cli = manage.PlacementCommands()
         self.useFixture(fixtures.MockPatch('nova.network.neutron.get_client'))
 
+    def test_heal_allocations_with_cell_instance_id(self):
+        """Test heal allocation with both cell id and instance id"""
+        cell_uuid = uuidutils.generate_uuid()
+        instance_uuid = uuidutils.generate_uuid()
+        self.assertEqual(127, self.cli.heal_allocations(
+                        instance_uuid=instance_uuid,
+                        cell_uuid=cell_uuid))
+        self.assertIn('The --cell and --instance options',
+        self.output.getvalue())
+
+    @mock.patch('nova.objects.CellMapping.get_by_uuid',
+                side_effect=exception.CellMappingNotFound(uuid='fake'))
+    def test_heal_allocations_with_cell_id_not_found(self, mock_get):
+        """Test the case where cell_id is not found"""
+        self.assertEqual(127, self.cli.heal_allocations(cell_uuid='fake'))
+        output = self.output.getvalue().strip()
+        self.assertEqual('Cell with uuid fake was not found.', output)
+
     @ddt.data(-1, 0, "one")
     def test_heal_allocations_invalid_max_count(self, max_count):
         self.assertEqual(127, self.cli.heal_allocations(max_count=max_count))
diff --git a/releasenotes/notes/register-allocation-per-cell-9177b3e2161a632c.yaml b/releasenotes/notes/register-allocation-per-cell-9177b3e2161a632c.yaml
new file mode 100644
index 000000000000..e109c64ed270
--- /dev/null
+++ b/releasenotes/notes/register-allocation-per-cell-9177b3e2161a632c.yaml
@@ -0,0 +1,4 @@
+---
+features:
+  - Add ``--cell`` option to the ``nova-manage placement heal_allocations``
+    command. This option allows healing instance allocations within a specific cell.