From 0f9ada1713977218fa0a36ed855eafa4ea975b9c Mon Sep 17 00:00:00 2001
From: Liam Young <liam.young@canonical.com>
Date: Mon, 8 Oct 2018 12:30:22 +0000
Subject: [PATCH] Fix assess status for super-conductor

In a cells deployment its possible that the top-level
nova-cloud-controller will have no compute nodes associated with it.
This change fixes the work load status in that scenario.

There is also a drive by fix to return empty contexts for the cell
db and amqp contexts if the relation do not yet exists.

Change-Id: Ia8eeccb6794dd016185eb0cfb05339b76cef9348
---
 hooks/nova_cc_context.py            | 17 +++++++++++++
 hooks/nova_cc_utils.py              |  9 ++++++-
 unit_tests/test_nova_cc_contexts.py | 37 +++++++++++++++++++++++++++++
 unit_tests/test_nova_cc_utils.py    |  5 ++--
 4 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/hooks/nova_cc_context.py b/hooks/nova_cc_context.py
index 70e9b6ce..9f5fcfca 100644
--- a/hooks/nova_cc_context.py
+++ b/hooks/nova_cc_context.py
@@ -75,6 +75,23 @@ class ApacheSSLContext(context.ApacheSSLContext):
         return super(ApacheSSLContext, self).__call__()
 
 
+class NovaCellV2Context(context.OSContextGenerator):
+
+    interfaces = ['nova-cell-api']
+
+    def __call__(self):
+        ctxt = {}
+        required_keys = ['cell-name', 'amqp-service', 'db-service']
+        for rid in relation_ids('nova-cell-api'):
+            for unit in related_units(rid):
+                data = relation_get(rid=rid, unit=unit)
+                if set(required_keys).issubset(data.keys()):
+                    ctxt[data['cell-name']] = {
+                        'amqp_service': data['amqp-service'],
+                        'db_service': data['db-service']}
+        return ctxt
+
+
 class NovaCellV2SharedDBContext(context.OSContextGenerator):
     interfaces = ['shared-db']
 
diff --git a/hooks/nova_cc_utils.py b/hooks/nova_cc_utils.py
index 35eda470..deb9c397 100644
--- a/hooks/nova_cc_utils.py
+++ b/hooks/nova_cc_utils.py
@@ -124,7 +124,7 @@ REQUIRED_INTERFACES = {
     'messaging': ['amqp'],
     'identity': ['identity-service'],
     'image': ['image-service'],
-    'compute': ['nova-compute'],
+    'compute': ['nova-compute', 'nova-cell-api'],
 }
 
 # removed from original: charm-helper-sh
@@ -1364,6 +1364,9 @@ def assess_status(configs):
     @param configs: a templating.OSConfigRenderer() object
     @returns None - this function is executed for its side-effect
     """
+    # Add the cell context as its not used for rendering files, only for
+    # assessing status.
+    configs.register('', [nova_cc_context.NovaCellV2Context()])
     assess_status_func(configs)()
     os_application_version_set(VERSION_PACKAGE)
 
@@ -1515,6 +1518,8 @@ def get_cell_db_context(db_service):
     db_rid = relation_id(
         relation_name='shared-db-cell',
         service_or_unit=db_service)
+    if not db_rid:
+        return {}
     return context.SharedDBContext(
         relation_prefix='nova',
         ssl_dir=NOVA_CONF_DIR,
@@ -1526,6 +1531,8 @@ def get_cell_amqp_context(amqp_service):
     amq_rid = relation_id(
         relation_name='amqp-cell',
         service_or_unit=amqp_service)
+    if not amq_rid:
+        return {}
     return context.AMQPContext(
         ssl_dir=NOVA_CONF_DIR,
         relation_id=amq_rid)()
diff --git a/unit_tests/test_nova_cc_contexts.py b/unit_tests/test_nova_cc_contexts.py
index cbf2ff4a..4167c3c3 100644
--- a/unit_tests/test_nova_cc_contexts.py
+++ b/unit_tests/test_nova_cc_contexts.py
@@ -438,3 +438,40 @@ class NovaComputeContextTests(CharmTestCase):
         ctxt = context.NovaMetadataContext()()
 
         self.assertEqual(ctxt, {'enable_metadata': False})
+
+    def test_NovaCellV2Context(self):
+        settings = {'cell-name': 'cell32',
+                    'amqp-service': 'rabbitmq-cell2',
+                    'db-service': 'percona-cell2'}
+
+        def fake_rel_get(attribute=None, unit=None, rid=None):
+            if attribute:
+                return settings.get(attribute)
+
+            return settings
+
+        self.relation_get.side_effect = fake_rel_get
+        self.relation_ids.return_value = ['nova-cell:0']
+        self.related_units.return_value = ['nova-cell-conductor/0']
+        ctxt = context.NovaCellV2Context()()
+        self.assertEqual(
+            ctxt,
+            {'cell32': {
+                'amqp_service': 'rabbitmq-cell2',
+                'db_service': 'percona-cell2'}})
+
+    def test_NovaCellV2Context_missing_amqp(self):
+        settings = {'cell-name': 'cell32',
+                    'db-service': 'percona-cell2'}
+
+        def fake_rel_get(attribute=None, unit=None, rid=None):
+            if attribute:
+                return settings.get(attribute)
+
+            return settings
+
+        self.relation_get.side_effect = fake_rel_get
+        self.relation_ids.return_value = ['nova-cell:0']
+        self.related_units.return_value = ['nova-cell-conductor/0']
+        ctxt = context.NovaCellV2Context()()
+        self.assertEqual(ctxt, {})
diff --git a/unit_tests/test_nova_cc_utils.py b/unit_tests/test_nova_cc_utils.py
index 5e6ccad0..6d429022 100644
--- a/unit_tests/test_nova_cc_utils.py
+++ b/unit_tests/test_nova_cc_utils.py
@@ -1035,10 +1035,11 @@ class NovaCCUtilsTests(CharmTestCase):
 
     def test_assess_status(self):
         with patch.object(utils, 'assess_status_func') as asf:
+            configs = MagicMock()
             callee = MagicMock()
             asf.return_value = callee
-            utils.assess_status('test-config')
-            asf.assert_called_once_with('test-config')
+            utils.assess_status(configs)
+            asf.assert_called_once_with(configs)
             callee.assert_called_once_with()
             self.os_application_version_set.assert_called_with(
                 utils.VERSION_PACKAGE