Update hook to remove old ceph.conf alternatives

When adding ceph-mon relation to cinder, the charm installs ceph.conf
with the update-alternatives via cinder_utils.resource_map().
However when the relation is removed, the alternative isn't cleaned up.
This can cause issues if installing a cinder-ceph subordinate charm.
The cinder-ceph charm also installs a ceph.conf alternative that will
point to the leftover ceph.conf installed by the ceph-mon charm.

Added remove_alternative() in ceph-relation-broken hook to ensure
that leftover ceph.conf alternatives is removed upon relation removal.

Change-Id: I308e62a626f31eb8ef690a09035fe3908920ccc9
Closes-Bug: 1778084

hooks/cinder_hooks.py

@@ -26,8 +26,12 @@ from cinder_utils import (
     PACKAGES,
     REQUIRED_INTERFACES,
     VERSION_PACKAGE,
+    CEPH_CONF,
+)
+from cinder_contexts import (
+    CephSubordinateContext,
+    ceph_config_file,
 )
-from cinder_contexts import CephSubordinateContext
 from charmhelpers.contrib.openstack.context import CephContext
 
 from charmhelpers.core.hookenv import (
@@ -48,6 +52,7 @@ from charmhelpers.core.host import (
     restart_on_change,
     service_restart,
 )
+from charmhelpers.contrib.openstack.alternatives import remove_alternative
 from charmhelpers.contrib.storage.linux.ceph import (
     send_request_if_needed,
     is_request_complete,
@@ -142,6 +147,7 @@ def ceph_broken():
     service = service_name()
     delete_keyring(service=service)
     CONFIGS.write_all()
+    remove_alternative(os.path.basename(CEPH_CONF), ceph_config_file())
 
 
 @hooks.hook('config-changed')

hooks/cinder_utils.py

@@ -24,6 +24,7 @@ from tempfile import NamedTemporaryFile
 from charmhelpers.core.hookenv import (
     relation_ids,
     service_name,
+    hook_name,
 )
 
 from charmhelpers.contrib.openstack import (
@@ -78,7 +79,7 @@ def register_configs():
 
     confs = []
 
-    if relation_ids('ceph'):
+    if relation_ids('ceph') and hook_name() != 'ceph-relation-broken':
         # Add charm ceph configuration to resources and
         # ensure directory actually exists
         mkdir(os.path.dirname(ceph_config_file()))

unit_tests/test_cinder_hooks.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 from mock import MagicMock, patch, call, ANY
+import os
 import json
 import cinder_utils as utils
 
@@ -35,6 +36,8 @@ TO_PATCH = [
     'is_request_complete',
     'send_request_if_needed',
     'CONFIGS',
+    'CEPH_CONF',
+    'ceph_config_file',
     # charmhelpers.core.hookenv
     'config',
     'relation_ids',
@@ -52,6 +55,7 @@ TO_PATCH = [
     'execd_preinstall',
     'CephSubordinateContext',
     'delete_keyring',
+    'remove_alternative',
     'status_set',
     'os_application_version_set',
 ]
@@ -168,6 +172,9 @@ class TestCinderHooks(CharmTestCase):
         hooks.hooks.execute(['hooks/ceph-relation-broken'])
         self.delete_keyring.assert_called_with(service='cinder-ceph')
         self.assertTrue(self.CONFIGS.write_all.called)
+        self.remove_alternative.assert_called_with(
+            os.path.basename(self.CEPH_CONF),
+            self.ceph_config_file())
 
     @patch('charmhelpers.core.hookenv.config')
     @patch.object(hooks, 'storage_backend')