Add identity-credentials relation support

Implement support for the identity-credentials relation as an
alternative way to get keystone credentials when we are not registering
a service endpoint via the identity-service relation.

This solves an issue where the image volume cache does not work when the
cinder volume service is deployed as a second cinder application
('cinder-volume') having enabled-services=volume set.

Previously the following items were missing from cinder.conf:
cinder_internal_tenant_project_id
cinder_internal_tenant_user_id

Resulting in the image cache not functioning with the following warnings:
Unable to get internal tenant context: Missing required config
parameters.
Unable to get Cinder internal context, will not use image-volume cache.

As there are now two possible interfaces to keystone ('identity-service'
and 'identity-credentials') any existing bundles that don't specify the
interface 'identity-service' when relating to keystone will fail to
deploy and will need to be updated.

Closes-Bug: #1978452
Change-Id: Ieef500c9c55eb3968b3e2e231a8ff6e2a5ec148d

README.md

@@ -66,6 +66,32 @@ Cinder can be backed by a Pure Storage appliance reachable by its API endpoint.
 This functionality is provided by the
 [cinder-purestorage][cinder-purestorage-charm] subordinate charm.
 
+## Separate Volume Service
+
+For certain operations when an instance is not involved, the cinder application
+will connect directly to the storage for operations such as cloning a volume
+from a glance image. You can deploy a second cinder application for the volume
+service only where the primary cinder application cannot connect to this
+storage. This may be required for iSCSI connections because LXD containers
+cannot create iSCSI connections or where you need a physical Fibre Channel
+connection. This is not required for Ceph deployments which use userspace RBD
+tools.
+
+1. Deploy cinder with enabled-services=api,scheduler
+2. Deploy a second application of cinder named 'cinder-volume' with
+   enabled-services=volume
+3. Relate the storage subordinate (e.g. cinder-purestorage) to the
+   cinder-volume application only (not to the 'cinder' application)
+4. Keystone should be related to cinder:identity-__service__ but
+   cinder-volume:identity-__credentials__
+
+   The primary cinder application gets keystone credentials when registering a
+   service endpoint via the identity-service relation. The cinder-volume
+   application does not register a service, so we need to relate
+   identity-credentials instead. The image volume cache will not work without
+   this relation.
+5. Both cinder and cinder-volume should otherwise have the same relations
+
 ## High availability
 
 This charm supports high availability via HAcluster.

hooks/cinder_hooks.py

@@ -469,6 +469,21 @@ def identity_changed():
         configure_https()
 
 
+@hooks.hook('identity-credentials-relation-joined')
+def identity_credentials_joined(rid=None):
+    if service_enabled('volume') and not service_enabled('api'):
+        settings = {'username': 'cinder', 'requested_roles': 'Admin'}
+        relation_set(relation_id=rid, **settings)
+
+
+@hooks.hook('identity-credentials-relation-changed')
+@restart_on_change(restart_map())
+def identity_credentials_changed():
+    if service_enabled('volume') and not service_enabled('api'):
+        if 'identity-credentials' in CONFIGS.complete_contexts():
+            CONFIGS.write(CINDER_CONF)
+
+
 @hooks.hook('ceph-relation-joined')
 def ceph_joined():
     if not os.path.isdir('/etc/ceph'):
@@ -586,6 +601,7 @@ def image_service_changed():
 
 @hooks.hook('amqp-relation-broken',
             'identity-service-relation-broken',
+            'identity-credentials-relation-broken',
             'image-service-relation-broken',
             'shared-db-relation-broken')
 @restart_on_change(restart_map(), stopstart=True)

hooks/cinder_utils.py

@@ -224,6 +224,9 @@ BASE_RESOURCE_MAP = OrderedDict([
                          config_file=CINDER_CONF),
                      cinder_contexts.StorageBackendContext(),
                      cinder_contexts.LoggingConfigContext(),
+                     context.IdentityCredentialsContext(
+                         service='cinder',
+                         service_user='cinder'),
                      context.IdentityServiceContext(
                          service='cinder',
                          service_user='cinder'),
@@ -931,6 +934,9 @@ def get_optional_interfaces():
     if relation_ids('image-service'):
         optional_interfaces['image'] = ['image-service']
 
+    if service_enabled('volume') and not service_enabled('api'):
+        optional_interfaces['identity-credentials'] = ['identity-credentials']
+
     return optional_interfaces
 
 

hooks/identity-credentials-relation-broken

@@ -0,0 +1 @@
+cinder_hooks.py

hooks/identity-credentials-relation-changed

@@ -0,0 +1 @@
+cinder_hooks.py

hooks/identity-credentials-relation-joined

@@ -0,0 +1 @@
+cinder_hooks.py

metadata.yaml

@@ -27,6 +27,9 @@ requires:
     interface: rabbitmq
   identity-service:
     interface: keystone
+    optional: true
+  identity-credentials:
+    interface: keystone-credentials
   ceph:
     interface: ceph-client
   image-service:

unit_tests/test_cinder_hooks.py

@@ -127,6 +127,14 @@ class TestChangedHooks(CharmTestCase):
         'identity-service': ['identity-service:1'],
     }
 
+    def svc_enabled(self, svc):
+        enabled = self.test_config.get('enabled-services')
+
+        if enabled == 'all':
+            return True
+
+        return svc in enabled
+
     def setUp(self):
         super(TestChangedHooks, self).setUp(hooks, TO_PATCH)
         self.config.side_effect = self.test_config.get
@@ -329,6 +337,42 @@ class TestChangedHooks(CharmTestCase):
         hooks.hooks.execute(['hooks/identity-service-relation-changed'])
         self.assertFalse(self.CONFIGS.write.called)
 
+    @patch.object(hooks, 'service_enabled')
+    def test_identity_credentials_joined_without_api(self, service_enabled):
+        'It requests keystone credentials without API service'
+        self.test_config.set('enabled-services', 'volume')
+        service_enabled.side_effect = self.svc_enabled
+        hooks.hooks.execute(['hooks/identity-credentials-relation-joined'])
+        expected = {'relation_id': None,
+                    'username': 'cinder',
+                    'requested_roles': 'Admin'}
+        self.relation_set.assert_called_with(**expected)
+
+    @patch.object(hooks, 'service_enabled')
+    def test_identity_credentials_joined_with_api(self, service_enabled):
+        'It requests keystone credentials with API service'
+        self.test_config.set('enabled-services', 'all')
+        service_enabled.side_effect = self.svc_enabled
+        hooks.hooks.execute(['hooks/identity-credentials-relation-joined'])
+        self.relation_set.assert_not_called()
+
+    @patch.object(hooks, 'service_enabled')
+    def test_identity_credentials_changed(self, service_enabled):
+        'It writes out cinder.conf on identity-credentials changed'
+        self.CONFIGS.complete_contexts.return_value = ['identity-credentials']
+        self.test_config.set('enabled-services', 'volume')
+        service_enabled.side_effect = self.svc_enabled
+        hooks.hooks.execute(['hooks/identity-credentials-relation-changed'])
+        self.CONFIGS.write.assert_called_with('/etc/cinder/cinder.conf')
+
+    @patch.object(hooks, 'service_enabled')
+    def test_identity_credentials_changed_incomplete(self, service_enabled):
+        'It does not write cinder.conf with incomplete identity-service'
+        self.test_config.set('enabled-services', 'volume')
+        service_enabled.side_effect = self.svc_enabled
+        hooks.hooks.execute(['hooks/identity-credentials-relation-changed'])
+        self.assertFalse(self.CONFIGS.write.called)
+
     @patch.object(hooks, 'identity_joined')
     def test_configure_https_enable(self, identity_joined):
         'It enables https from hooks when we have https data'