Limit allocation candidates (v1.15, v1.16)

v1.15:
Microversion 1.15 does not need any support in osc
so we just skip over that in this patch.

v1.16:
New optional parameter to allocation candidate list:
    --limit N

Change-Id: Ic23dc4274c6fe42bfdf97fec55ddf0c36462501c
Partially-Implements: blueprint placement-osc-plugin-rocky

osc_placement/resources/allocation_candidate.py

@@ -68,6 +68,14 @@ class ListAllocationCandidate(command.Lister, version.CheckerMixin):
                  '``--resource VCP=4 --resource DISK_GB=64 '
                  '--resource MEMORY_MB=2048``'
         )
+        parser.add_argument(
+            '--limit',
+            metavar='<limit>',
+            help='A positive integer to limit '
+                 'the maximum number of allocation candidates. '
+                 'This option requires at least '
+                 '``--os-placement-api-version 1.16``.'
+        )
 
         return parser
 
@@ -81,6 +89,10 @@ class ListAllocationCandidate(command.Lister, version.CheckerMixin):
 
         params = {'resources': ','.join(
             resource.replace('=', ':') for resource in parsed_args.resource)}
+        if 'limit' in parsed_args and parsed_args.limit:
+            # Fail if --limit but not high enough microversion.
+            self.check_version(version.ge('1.16'))
+            params['limit'] = int(parsed_args.limit)
         resp = http.request('GET', BASE_URL, params=params).json()
 
         rps = {}

osc_placement/tests/functional/base.py

@@ -258,7 +258,9 @@ class BaseTestCase(base.BaseTestCase):
         cmd = 'resource provider trait delete %s ' % uuid
         self.openstack(cmd)
 
-    def allocation_candidate_list(self, *resources):
+    def allocation_candidate_list(self, resources, limit=None):
         cmd = 'allocation candidate list ' + ' '.join(
             '--resource %s' % resource for resource in resources)
+        if limit is not None:
+            cmd += ' --limit %d' % limit
         return self.openstack(cmd, use_json=True)

osc_placement/tests/functional/test_allocation_candidate.py

@@ -29,12 +29,13 @@ class TestAllocationCandidate(base.BaseTestCase):
 
     def test_list_empty(self):
         self.assertEqual([], self.allocation_candidate_list(
-            'MEMORY_MB=999999999'))
+            resources=['MEMORY_MB=999999999']))
 
     def test_list_one(self):
         rp = self.resource_provider_create()
         self.resource_inventory_set(rp['uuid'], 'MEMORY_MB=1024')
-        candidates = self.allocation_candidate_list('MEMORY_MB=256')
+        candidates = self.allocation_candidate_list(
+            resources=('MEMORY_MB=256',))
         self.assertIn(
             rp['uuid'],
             [candidate['resource provider'] for candidate in candidates])
@@ -50,7 +51,7 @@ class TestAllocationCandidate(base.BaseTestCase):
         self.resource_inventory_set(
             rp2['uuid'], 'MEMORY_MB=16384', 'DISK_GB=1024')
         candidates = self.allocation_candidate_list(
-            'MEMORY_MB=1024', 'DISK_GB=80')
+            resources=('MEMORY_MB=1024', 'DISK_GB=80'))
         rps = {c['resource provider']: c for c in candidates}
         self.assertResourceEqual(
             'MEMORY_MB=1024,DISK_GB=80', rps[rp1['uuid']]['allocation'])
@@ -74,7 +75,7 @@ class TestAllocationCandidate(base.BaseTestCase):
         self.resource_provider_trait_set(
             rp2['uuid'], 'MISC_SHARES_VIA_AGGREGATE')
         candidates = self.allocation_candidate_list(
-            'MEMORY_MB=1024', 'DISK_GB=80')
+            resources=('MEMORY_MB=1024', 'DISK_GB=80'))
         rps = {c['resource provider']: c for c in candidates}
         self.assertResourceEqual(
             'MEMORY_MB=1024', rps[rp1['uuid']]['allocation'])
@@ -89,8 +90,31 @@ class TestAllocationCandidate(base.BaseTestCase):
 
     def test_fail_if_unknown_rc(self):
         self.assertCommandFailed(
-            'No such resource', self.allocation_candidate_list, 'UNKNOWN=10')
+            'No such resource',
+            self.allocation_candidate_list,
+            resources=('UNKNOWN=10',))
 
 
 class TestAllocationCandidate112(TestAllocationCandidate):
     VERSION = '1.12'
+
+
+class TestAllocationCandidate116(base.BaseTestCase):
+    VERSION = '1.16'
+
+    def test_list_limit(self):
+        rp1 = self.resource_provider_create()
+        rp2 = self.resource_provider_create()
+        self.resource_inventory_set(
+            rp1['uuid'], 'MEMORY_MB=8192', 'DISK_GB=512')
+        self.resource_inventory_set(
+            rp2['uuid'], 'MEMORY_MB=8192', 'DISK_GB=512')
+
+        unlimited = self.allocation_candidate_list(
+            resources=('MEMORY_MB=1024', 'DISK_GB=80'))
+        self.assertTrue(len(set([row['#'] for row in unlimited])) > 1)
+
+        limited = self.allocation_candidate_list(
+            resources=('MEMORY_MB=1024', 'DISK_GB=80'),
+            limit=1)
+        self.assertEqual(len(set([row['#'] for row in limited])), 1)

osc_placement/version.py

@@ -29,7 +29,9 @@ SUPPORTED_VERSIONS = [
     '1.11',
     '1.12',
     '1.13',  # unused
-    '1.14'
+    '1.14',
+    '1.15',  # unused
+    '1.16'
 ]
 
 

releasenotes/notes/microversion-1.16-alloc-candidates-limit-8310675ecc99a82a.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    Support is added for the `1.16`_ placement API microversion by adding
+    the ``--limit`` option to the ``openstack allocation candidate list``
+    command.
+
+    .. _1.16: https://docs.openstack.org/nova/latest/user/placement.html#limit-allocation-candidates