Add support for cinder storage backend

Create new glance_api.conf template from Ussuri release to
use default_backend and enabled_backends configuration
parameters instead of deprecated stores, default_store
parameters.
Add new config option cinder-volume-types to specify the
volume types in cinder that can be used to store glance
images.
Add logic to update cinder in glance-api configurations
if cinder-volume-service relation is joined.

Also add two flags, cinder_http_retries and
cinder_state_transition_timeout

Closes-Bug: #1905042
Change-Id: Ife649defc9b765b433d7973ab31778f9cb1efdd9

README.md

@@ -28,7 +28,7 @@ pool type' and 'Ceph backed storage' for more information.
 
 ## Deployment
 
-This section includes four different deployment scenarios (with their
+This section includes five different deployment scenarios (with their
 respective backends). Each scenario requires these applications to be present:
 keystone, nova-cloud-controller, nova-compute, and a cloud database.
 
@@ -49,7 +49,7 @@ Ceph cluster via the ceph-mon charm:
     juju deploy --to lxd:1 glance
     juju add-relation glance:ceph ceph-mon:client
 
-Proceed with a group of commands common to all three scenarios:
+Proceed with a group of commands common to all four scenarios:
 
     juju add-relation glance:identity-service keystone:identity-service
     juju add-relation glance:image-service nova-cloud-controller:image-service
@@ -116,6 +116,25 @@ S3 server information can be passed via charm config options:
   Enabling S3 backend overrides `expose-image-locations` as false not to
   expose S3 credentials through Glance API.
 
+### Cinder LVM-backed storage
+
+Glance can also use Cinder LVM-backed storage as its storage backend, the
+configuration option cinder-volume-types can be used to specify the volume
+types in Cinder. The steps below assume a pre-existing Cinder LVM-backed
+deployment (see the [cinder][cinder-charm] and [cinder-lvm][cinder-lvm-charm]
+charms).
+
+Here, Glance is deployed to machine '1' and related to Cinder:
+
+    juju deploy --to 1 glance
+    juju add-relation cinder:image-service glance:image-service
+    juju add-relation cinder:cinder-volume-service glance:cinder-volume-service
+
+Proceed with the common group of commands from the Ceph scenario.
+
+> **Note**: To support Cinder LVM-backed storage, Glance unit should be deployed
+  on a baremetal machine or a virtual machine.
+
 ### Local storage
 
 Glance can simply use the storage available on the application unit's machine
@@ -133,6 +152,7 @@ Multiple storage backend support allows for one backend of each type:
 * Ceph
 * Swift (includes Ceph RADOS Gateway)
 * S3
+* Cinder
 * local
 
 With multiple backends configured, the cloud operator can specify, at image
@@ -142,7 +162,7 @@ using the `--store` option to the `glance` CLI client:
     glance image-create --store <backend-name> ...
 
 The default order of precedence is given by the following backend names:
-'ceph', 'swift', 's3', and then 'local'.
+'ceph', 'swift', 's3', 'cinder', and then 'local'.
 
 > **Important**: The backend name of 'swift' denotes both object storage
   solutions: Swift and Ceph RADOS Gateway. Only one of these solutions can
@@ -359,3 +379,5 @@ Please report bugs on [Launchpad][lp-bugs-charm-glance].
 [ceph-bluestore-compression]: https://docs.ceph.com/en/latest/rados/configuration/bluestore-config-ref/#inline-compression
 [upstream-glance]: https://docs.openstack.org/glance/latest/
 [juju-docs-actions]: https://jaas.ai/docs/actions
+[cinder-charm]: https://jaas.ai/cinder
+[cinder-lvm-charm]: https://jaas.ai/cinder-lvm

config.yaml

@@ -213,6 +213,24 @@ options:
       Device class from CRUSH map to use for placement groups for
       erasure profile - valid values: ssd, hdd or nvme (or leave
       unset to not use a device class).
+  cinder-volume-types:
+    type: string
+    default:
+    description: |
+      Comma separated list of cinder volume_types that can be configured
+      as cinder storage backends. The first one in the list will be
+      configured as the default backend.
+  cinder-http-retries:
+    type: int
+    default: 3
+    description: |
+      Number of cinderclient retries on failed http calls.
+  cinder-state-transition-timeout:
+    type: int
+    default: 30
+    description: |
+      Time period of time in seconds to wait for a cinder volume transition
+      to complete.
   worker-multiplier:
     type: float
     default:

hooks/glance_contexts.py

@@ -31,7 +31,8 @@ from charmhelpers.core.hookenv import (
 from charmhelpers.contrib.openstack.context import (
     OSContextGenerator,
     ApacheSSLContext as SSLContext,
-    BindHostContext
+    BindHostContext,
+    VolumeAPIContext,
 )
 
 from charmhelpers.contrib.hahelpers.cluster import (
@@ -275,6 +276,13 @@ class MultiBackendContext(OSContextGenerator):
         }
         return ctx
 
+    def _get_cinder_config(self):
+        cinder_ctx = CinderStoreContext()()
+        if not cinder_ctx or cinder_ctx.get("cinder_store", False) is False:
+            return
+
+        return cinder_ctx
+
     def __call__(self):
         ctxt = {
             "enabled_backend_configs": {},
@@ -310,11 +318,54 @@ class MultiBackendContext(OSContextGenerator):
             if not ctxt["default_store_backend"]:
                 ctxt["default_store_backend"] = "s3"
 
+        cinder_ctx = self._get_cinder_config()
+        if cinder_ctx:
+            cinder_volume_types = config('cinder-volume-types')
+            volume_types_str = cinder_volume_types or 'cinder'
+            volume_types = volume_types_str.split(',')
+            default_backend = volume_types[0]
+            for volume_type in volume_types:
+                backends.append(volume_type+':cinder')
+
+            # Add backend cinder_volume_type if cinder-volume-types configured
+            # In case cinder-volume-types not configured in charm, glance-api
+            # backend cinder_volume_type should be left blank so that glance
+            # creates volume in cinder without specifying any volume type.
+            if cinder_volume_types:
+                for volume_type in volume_types:
+                    ctxt['enabled_backend_configs'][volume_type] = {
+                        'cinder_volume_type': volume_type,
+                        'cinder_http_retries': config('cinder-http-retries'),
+                        'cinder_state_transition_timeout': config(
+                            'cinder-state-transition-timeout'),
+                    }
+            else:
+                # default cinder volume type cinder
+                ctxt['enabled_backend_configs']['cinder'] = {
+                    'cinder_http_retries': config('cinder-http-retries'),
+                    'cinder_state_transition_timeout': config(
+                        'cinder-state-transition-timeout'),
+                }
+
+            # Add internal endpoints if use-internal-endpoints set to true
+            if config('use-internal-endpoints'):
+                vol_api_ctxt = VolumeAPIContext('glance-common')()
+                volume_catalog_info = vol_api_ctxt['volume_catalog_info']
+                for volume_type in volume_types:
+                    if 'volume_type' not in ctxt['enabled_backend_configs']:
+                        ctxt['enabled_backend_configs'][volume_type] = {}
+                    ctxt['enabled_backend_configs'][volume_type].update(
+                        {'cinder_catalog_info': volume_catalog_info})
+
+            if not ctxt["default_store_backend"]:
+                ctxt["default_store_backend"] = default_backend
+
         if local_fs and not ctxt["default_store_backend"]:
             ctxt["default_store_backend"] = "local"
 
         if len(backends) > 0:
             ctxt["enabled_backends"] = ", ".join(backends)
+
         return ctxt
 
 

hooks/glance_relations.py

@@ -78,9 +78,11 @@ from charmhelpers.core.hookenv import (
 )
 
 from charmhelpers.core.host import (
+    is_container,
     # restart_on_change,
     service_reload,
     service_restart,
+    service_start,
     service_stop,
 )
 from charmhelpers.fetch import (
@@ -188,6 +190,12 @@ def install_hook():
         'glance',
         restart_handler=lambda: service_restart('glance-api'))
 
+    # Make sure iscsid has a unique InitiatorName by starting iscsid
+    # and invoking /lib/open-iscsi/startup-checks.sh indirectly as
+    # ExecStartPre script of it
+    if not is_container():
+        service_start('iscsid')
+
 
 @hooks.hook('shared-db-relation-joined')
 def db_joined():
@@ -494,6 +502,12 @@ def upgrade_charm():
         'glance',
         restart_handler=lambda: service_restart('glance-api'))
 
+    # Make sure iscsid has a unique InitiatorName by starting iscsid
+    # and invoking /lib/open-iscsi/startup-checks.sh indirectly as
+    # ExecStartPre script of it
+    if not is_container():
+        service_start('iscsid')
+
 
 @hooks.hook('ha-relation-joined')
 def ha_relation_joined(relation_id=None):

hooks/glance_utils.py

@@ -44,6 +44,7 @@ from charmhelpers.core.hookenv import (
 
 from charmhelpers.core.host import (
     CompareHostReleases,
+    is_container,
     lsb_release,
     mkdir,
     service_stop,
@@ -519,6 +520,11 @@ def check_optional_config_and_relations(configs):
     except ValueError as e:
         return ('blocked', 'Invalid external S3 config: {}'.format(str(e)))
 
+    if relation_ids('cinder-volume-service') and is_container():
+        return (
+            'blocked',
+            'Glance with cinder storage backend is not supported on container')
+
     # return 'unknown' as the lowest priority to not clobber an existing
     # status.
     return "unknown", ""

templates/ussuri/glance-api.conf

@@ -0,0 +1,86 @@
+[DEFAULT]
+verbose = {{ verbose }}
+use_syslog = {{ use_syslog }}
+debug = {{ debug }}
+workers = {{ workers }}
+bind_host = {{ bind_host }}
+
+{% if ext -%}
+bind_port = {{ ext }}
+{% elif bind_port -%}
+bind_port = {{ bind_port }}
+{% else -%}
+bind_port = 9292
+{% endif -%}
+
+{% if transport_url %}
+transport_url = {{ transport_url }}
+{% endif %}
+
+log_file = /var/log/glance/api.log
+backlog = 4096
+
+{% if expose_image_locations -%}
+show_multiple_locations = {{ expose_image_locations }}
+show_image_direct_url = {{ expose_image_locations }}
+{% endif -%}
+
+{% if api_config_flags -%}
+{% for key, value in api_config_flags.items() -%}
+{{ key }} = {{ value }}
+{% endfor -%}
+{% endif -%}
+
+delayed_delete = False
+scrub_time = 43200
+scrubber_datadir = /var/lib/glance/scrubber
+image_cache_dir = /var/lib/glance/image-cache/
+db_enforce_mysql_charset = False
+
+{% if image_size_cap -%}
+image_size_cap = {{ image_size_cap }}
+{% endif -%}
+
+{% if enabled_backends %}
+enabled_backends = {{ enabled_backends }}
+{% endif %}
+
+[glance_store]
+{% if default_store_backend %}
+default_backend = {{ default_store_backend }}
+{% endif %}
+
+[image_format]
+disk_formats = {{ disk_formats }}
+{% if container_formats -%}
+container_formats = {{ container_formats }}
+{% endif -%}
+
+{% include "section-keystone-authtoken-v3only" %}
+
+{% if auth_host -%}
+[paste_deploy]
+flavor = keystone
+{% endif %}
+
+[barbican]
+auth_endpoint = {{ service_protocol }}://{{ service_host }}:{{ service_port }}/v3
+
+{% include "parts/section-database" %}
+
+{% include "section-oslo-messaging-rabbit" %}
+
+{% include "section-oslo-notifications" %}
+
+{% include "section-oslo-middleware" %}
+
+{% include "parts/section-storage" %}
+
+{% for name, cfg in enabled_backend_configs.items() %}
+[{{name}}]
+{% for key, val in cfg.items() -%}
+{{ key }} = {{ val }}
+{% endfor -%}
+{% endfor%}
+
+{% include "parts/section-image-import" %}

tests/bundles/focal-xena.yaml

@@ -25,6 +25,7 @@ machines:
   '13':
   '14':
   '15':
+  '16':
 
 applications:
 
@@ -34,6 +35,9 @@ applications:
   glance-mysql-router:
     charm: ch:mysql-router
     channel: latest/edge
+  cinder-mysql-router:
+    charm: ch:mysql-router
+    channel: latest/edge
 
   mysql-innodb-cluster:
     charm: ch:mysql-innodb-cluster
@@ -115,6 +119,31 @@ applications:
     to:
       - '14'
 
+  cinder:
+    expose: True
+    charm: ch:cinder
+    num_units: 1
+    storage:
+      block-devices: '10G'
+    options:
+      openstack-origin: *openstack-origin
+      glance-api-version: 2
+      block-device: None
+    to:
+      - '16'
+    channel: latest/edge
+
+  cinder-lvm:
+    charm: ch:/cinder-lvm
+    options:
+      block-device: '/tmp/vol1|4G'
+      alias: zaza-lvm
+      overwrite: "true"
+      ephemeral-unmount: /mnt
+      allocation-type: auto
+      config-flags: target_helper=lioadm
+    channel: latest/edge
+
 relations:
   - - 'keystone:shared-db'
     - 'keystone-mysql-router:shared-db'
@@ -144,3 +173,21 @@ relations:
     - 'keystone:identity-service'
   - - 'ceph-radosgw:object-store'
     - 'glance:object-store'
+
+  - - 'cinder:shared-db'
+    - 'cinder-mysql-router:shared-db'
+  - - 'cinder-mysql-router:db-router'
+    - 'mysql-innodb-cluster:db-router'
+
+  - - 'cinder:identity-service'
+    - 'keystone:identity-service'
+
+  - - 'cinder:amqp'
+    - 'rabbitmq-server:amqp'
+
+  - - 'cinder:image-service'
+    - 'glance:image-service'
+  - - 'cinder:cinder-volume-service'
+    - 'glance:cinder-volume-service'
+  - - 'cinder-lvm:storage-backend'
+    - 'cinder:storage-backend'

tests/bundles/focal-yoga.yaml

@@ -25,6 +25,7 @@ machines:
   '13':
   '14':
   '15':
+  '16':
 
 applications:
 
@@ -34,6 +35,9 @@ applications:
   glance-mysql-router:
     charm: ch:mysql-router
     channel: latest/edge
+  cinder-mysql-router:
+    charm: ch:mysql-router
+    channel: latest/edge
 
   mysql-innodb-cluster:
     charm: ch:mysql-innodb-cluster
@@ -115,6 +119,31 @@ applications:
     to:
       - '14'
 
+  cinder:
+    expose: True
+    charm: ch:cinder
+    num_units: 1
+    storage:
+      block-devices: '10G'
+    options:
+      openstack-origin: *openstack-origin
+      glance-api-version: 2
+      block-device: None
+    to:
+      - '16'
+    channel: latest/edge
+
+  cinder-lvm:
+    charm: ch:cinder-lvm
+    options:
+      block-device: '/tmp/vol1|4G'
+      alias: zaza-lvm
+      overwrite: "true"
+      ephemeral-unmount: /mnt
+      allocation-type: auto
+      config-flags: target_helper=lioadm
+    channel: latest/edge
+
 relations:
   - - 'keystone:shared-db'
     - 'keystone-mysql-router:shared-db'
@@ -144,3 +173,21 @@ relations:
     - 'keystone:identity-service'
   - - 'ceph-radosgw:object-store'
     - 'glance:object-store'
+
+  - - 'cinder:shared-db'
+    - 'cinder-mysql-router:shared-db'
+  - - 'cinder-mysql-router:db-router'
+    - 'mysql-innodb-cluster:db-router'
+
+  - - 'cinder:identity-service'
+    - 'keystone:identity-service'
+
+  - - 'cinder:amqp'
+    - 'rabbitmq-server:amqp'
+
+  - - 'cinder:image-service'
+    - 'glance:image-service'
+  - - 'cinder:cinder-volume-service'
+    - 'glance:cinder-volume-service'
+  - - 'cinder-lvm:storage-backend'
+    - 'cinder:storage-backend'

tests/bundles/impish-xena.yaml

@@ -25,6 +25,7 @@ machines:
   '13':
   '14':
   '15':
+  '16':
 
 applications:
 
@@ -34,6 +35,9 @@ applications:
   glance-mysql-router:
     charm: ch:mysql-router
     channel: latest/edge
+  cinder-mysql-router:
+    charm: ch:mysql-router
+    channel: latest/edge
 
   mysql-innodb-cluster:
     charm: ch:mysql-innodb-cluster
@@ -115,6 +119,31 @@ applications:
     to:
       - '14'
 
+  cinder:
+    expose: True
+    charm: ch:cinder
+    num_units: 1
+    storage:
+      block-devices: '10G'
+    options:
+      openstack-origin: *openstack-origin
+      glance-api-version: 2
+      block-device: None
+    to:
+      - '16'
+    channel: latest/edge
+
+  cinder-lvm:
+    charm: ch:cinder-lvm
+    options:
+      block-device: '/tmp/vol1|4G'
+      alias: zaza-lvm
+      overwrite: "true"
+      ephemeral-unmount: /mnt
+      allocation-type: auto
+      config-flags: target_helper=lioadm
+    channel: latest/edge
+
 relations:
   - - 'keystone:shared-db'
     - 'keystone-mysql-router:shared-db'
@@ -144,3 +173,21 @@ relations:
     - 'keystone:identity-service'
   - - 'ceph-radosgw:object-store'
     - 'glance:object-store'
+
+  - - 'cinder:shared-db'
+    - 'cinder-mysql-router:shared-db'
+  - - 'cinder-mysql-router:db-router'
+    - 'mysql-innodb-cluster:db-router'
+
+  - - 'cinder:identity-service'
+    - 'keystone:identity-service'
+
+  - - 'cinder:amqp'
+    - 'rabbitmq-server:amqp'
+
+  - - 'cinder:image-service'
+    - 'glance:image-service'
+  - - 'cinder:cinder-volume-service'
+    - 'glance:cinder-volume-service'
+  - - 'cinder-lvm:storage-backend'
+    - 'cinder:storage-backend'

tests/bundles/jammy-yoga.yaml

@@ -25,6 +25,7 @@ machines:
   '13':
   '14':
   '15':
+  '16':
 
 applications:
 
@@ -34,6 +35,9 @@ applications:
   glance-mysql-router:
     charm: ch:mysql-router
     channel: latest/edge
+  cinder-mysql-router:
+    charm: ch:mysql-router
+    channel: latest/edge
 
   mysql-innodb-cluster:
     charm: ch:mysql-innodb-cluster
@@ -115,6 +119,31 @@ applications:
     to:
       - '14'
 
+  cinder:
+    expose: True
+    charm: ch:cinder
+    num_units: 1
+    storage:
+      block-devices: '10G'
+    options:
+      openstack-origin: *openstack-origin
+      glance-api-version: 2
+      block-device: None
+    to:
+      - '16'
+    channel: latest/edge
+
+  cinder-lvm:
+    charm: ch:cinder-lvm
+    options:
+      block-device: '/tmp/vol1|4G'
+      alias: zaza-lvm
+      overwrite: "true"
+      ephemeral-unmount: /mnt
+      allocation-type: auto
+      config-flags: target_helper=lioadm
+    channel: latest/edge
+
 relations:
   - - 'keystone:shared-db'
     - 'keystone-mysql-router:shared-db'
@@ -144,3 +173,21 @@ relations:
     - 'keystone:identity-service'
   - - 'ceph-radosgw:object-store'
     - 'glance:object-store'
+
+  - - 'cinder:shared-db'
+    - 'cinder-mysql-router:shared-db'
+  - - 'cinder-mysql-router:db-router'
+    - 'mysql-innodb-cluster:db-router'
+
+  - - 'cinder:identity-service'
+    - 'keystone:identity-service'
+
+  - - 'cinder:amqp'
+    - 'rabbitmq-server:amqp'
+
+  - - 'cinder:image-service'
+    - 'glance:image-service'
+  - - 'cinder:cinder-volume-service'
+    - 'glance:cinder-volume-service'
+  - - 'cinder-lvm:storage-backend'
+    - 'cinder:storage-backend'

tests/tests.yaml

@@ -28,6 +28,7 @@ tests:
   - zaza.openstack.charm_tests.glance.tests.GlanceTest
   - zaza.openstack.charm_tests.glance.tests.GlanceCephRGWBackendTest
   - zaza.openstack.charm_tests.glance.tests.GlanceExternalS3Test
+  - zaza.openstack.charm_tests.glance.tests.GlanceCinderBackendTest
   - zaza.openstack.charm_tests.policyd.tests.GlanceTests
   - zaza.openstack.charm_tests.ceph.tests.CheckPoolTypes
   - zaza.openstack.charm_tests.ceph.tests.BlueStoreCompressionCharmOperation

unit_tests/test_glance_contexts.py

@@ -294,8 +294,15 @@ class TestGlanceContexts(CharmTestCase):
             })
 
     def test_multi_backend_with_swift(self):
+        # return relation_ids only for swift but not for cinder
+        def _relation_ids(*args, **kwargs):
+            if args[0] == 'object-store':
+                return ["object-store:0"]
+
+            return []
+
         self.maxDiff = None
-        self.relation_ids.return_value = ["object-store:0"]
+        self.relation_ids.side_effect = _relation_ids
         self.is_relation_made.return_value = False
         data_dir = '/some/data/dir'
         conf_dict = {
@@ -321,6 +328,78 @@ class TestGlanceContexts(CharmTestCase):
                 'default_store_backend': 'swift',
             })
 
+    def test_multi_backend_with_cinder(self):
+        # return relation_ids only for cinder but not for swift
+        def _relation_ids(*args, **kwargs):
+            if args[0] == 'cinder-volume-service':
+                return ["cinder-volume-service:0"]
+
+            return []
+
+        self.maxDiff = None
+        self.relation_ids.side_effect = _relation_ids
+        self.is_relation_made.return_value = False
+        data_dir = '/some/data/dir'
+        conf_dict = {
+            'filesystem-store-datadir': data_dir,
+            'cinder-http-retries': 3,
+            'cinder-state-transition-timeout': 30,
+        }
+        self.config.side_effect = lambda x: conf_dict.get(x)
+        self.assertEqual(
+            contexts.MultiBackendContext()(),
+            {
+                'enabled_backend_configs': {
+                    'local': {
+                        'filesystem_store_datadir': data_dir,
+                        'store_description': 'Local filesystem store',
+                    },
+                    'cinder': {
+                        'cinder_http_retries': 3,
+                        'cinder_state_transition_timeout': 30,
+                    }
+                },
+                'enabled_backends': 'local:file, cinder:cinder',
+                'default_store_backend': 'cinder',
+            })
+
+    def test_multi_backend_with_cinder_volume_types_defined(self):
+        # return relation_ids only for cinder but not for swift
+        def _relation_ids(*args, **kwargs):
+            if args[0] == 'cinder-volume-service':
+                return ["cinder-volume-service:0"]
+
+            return []
+
+        self.maxDiff = None
+        self.relation_ids.side_effect = _relation_ids
+        self.is_relation_made.return_value = False
+        data_dir = '/some/data/dir'
+        conf_dict = {
+            'filesystem-store-datadir': data_dir,
+            'cinder-volume-types': 'volume-type-test',
+            'cinder-http-retries': 3,
+            'cinder-state-transition-timeout': 30,
+        }
+        self.config.side_effect = lambda x: conf_dict.get(x)
+        self.assertEqual(
+            contexts.MultiBackendContext()(),
+            {
+                'enabled_backend_configs': {
+                    'local': {
+                        'filesystem_store_datadir': data_dir,
+                        'store_description': 'Local filesystem store',
+                    },
+                    'volume-type-test': {
+                        'cinder_volume_type': 'volume-type-test',
+                        'cinder_http_retries': 3,
+                        'cinder_state_transition_timeout': 30,
+                    }
+                },
+                'enabled_backends': 'local:file, volume-type-test:cinder',
+                'default_store_backend': 'volume-type-test',
+            })
+
     def test_multi_backend_with_ceph_no_swift(self):
         self.maxDiff = None
         self.relation_ids.return_value = []
@@ -354,8 +433,15 @@ class TestGlanceContexts(CharmTestCase):
             })
 
     def test_multi_backend_with_ceph_and_swift(self):
+        # return relation_ids only for swift but not for cinder
+        def _relation_ids(*args, **kwargs):
+            if args[0] == 'object-store':
+                return ["object-store:0"]
+
+            return []
+
         self.maxDiff = None
-        self.relation_ids.return_value = ["object-store:0"]
+        self.relation_ids.side_effect = _relation_ids
         self.is_relation_made.return_value = True
         service = 'glance'
         self.service_name.return_value = service
@@ -391,6 +477,51 @@ class TestGlanceContexts(CharmTestCase):
                 'default_store_backend': 'ceph',
             })
 
+    def test_multi_backend_with_ceph_and_cinder(self):
+        # return relation_ids only for cinder but not for swift
+        def _relation_ids(*args, **kwargs):
+            if args[0] == 'cinder-volume-service':
+                return ["cinder-volume-service:0"]
+
+            return []
+
+        self.maxDiff = None
+        self.relation_ids.side_effect = _relation_ids
+        self.is_relation_made.return_value = True
+        service = 'glance'
+        self.service_name.return_value = service
+        data_dir = '/some/data/dir'
+        conf_dict = {
+            'filesystem-store-datadir': data_dir,
+            'rbd-pool-name': 'mypool',
+            'cinder-http-retries': 3,
+            'cinder-state-transition-timeout': 30,
+        }
+        self.config.side_effect = lambda x: conf_dict.get(x)
+        self.assertEqual(
+            contexts.MultiBackendContext()(),
+            {
+                'enabled_backend_configs': {
+                    'local': {
+                        'filesystem_store_datadir': data_dir,
+                        'store_description': 'Local filesystem store',
+                    },
+                    'ceph': {
+                        "rbd_store_chunk_size": 8,
+                        "rbd_store_pool": 'mypool',
+                        "rbd_store_user": service,
+                        "rados_connect_timeout": 0,
+                        "rbd_store_ceph_conf": "/etc/ceph/ceph.conf",
+                    },
+                    'cinder': {
+                        'cinder_http_retries': 3,
+                        'cinder_state_transition_timeout': 30,
+                    }
+                },
+                'enabled_backends': 'local:file, ceph:rbd, cinder:cinder',
+                'default_store_backend': 'ceph',
+            })
+
     def test_multi_backend_with_external_s3(self):
         self.maxDiff = None
         self.os_release.return_value = 'ussuri'

unit_tests/test_glance_relations.py

@@ -72,6 +72,7 @@ TO_PATCH = [
     'service_reload',
     'service_stop',
     'service_restart',
+    'service_start',
     # charmhelpers.contrib.openstack.utils
     'configure_installation_source',
     'is_db_initialised',