Clean up stale ceph keyring

[cbjchen,r=]
Clean up the keyring after ceph relation is broken. So when next
time ceph relation is joined, ensure_ceph_keyring will not ignore
the new key because of the existance of the old one.

hooks/cinder_hooks.py

@@ -30,6 +30,7 @@ from charmhelpers.contrib.storage.linux.ceph import (
     ensure_ceph_keyring,
     CephBrokerRq,
     CephBrokerRsp,
+    delete_keyring,
 )
 from charmhelpers.payload.execd import execd_preinstall
 
@@ -88,8 +89,14 @@ def ceph_changed():
             log("Request(s) sent to Ceph broker (rid=%s)" % (rid))
 
 
-@hooks.hook('ceph-relation-broken',
-            'config-changed')
+@hooks.hook('ceph-relation-broken')
+def ceph_broken():
+    service = service_name()
+    delete_keyring(service=service)
+    CONFIGS.write_all()
+
+
+@hooks.hook('config-changed')
 @restart_on_change(restart_map())
 def write_and_restart():
     CONFIGS.write_all()

unit_tests/test_cinder_hooks.py

@@ -31,7 +31,8 @@ TO_PATCH = [
     'apt_update',
     # charmhelpers.contrib.hahelpers.cluster_utils
     'execd_preinstall',
-    'CephSubordinateContext'
+    'CephSubordinateContext',
+    'delete_keyring'
 ]
 
 
@@ -91,6 +92,15 @@ class TestCinderHooks(CharmTestCase):
         self.assertTrue(self.log.called)
         self.assertFalse(self.CONFIGS.write_all.called)
 
+    @patch('charmhelpers.core.hookenv.config')
+    def test_ceph_broken(self, mock_config):
+        self.CONFIGS.complete_contexts.return_value = ['ceph']
+        self.service_name.return_value = 'cinder-ceph'
+        hooks.hooks.execute(['hooks/ceph-relation-changed'])
+        hooks.hooks.execute(['hooks/ceph-relation-broken'])
+        self.delete_keyring.assert_called_with(service='cinder-ceph')
+        self.assertTrue(self.CONFIGS.write_all.called)
+
     @patch('charmhelpers.core.hookenv.config')
     @patch.object(hooks, 'storage_backend')
     def test_upgrade_charm_related(self, _storage_backend, mock_config):