Fix the vault pause/resume test

The pause/resume test paused the lead unit, but then checked
the first unit.  In an HA scenario, the lead unit may not be the
first unit.  This PR changes the test to check the lead unit after
the pause/resume test.

Depends On: https://github.com/openstack-charmers/zaza/pull/327

zaza/openstack/charm_tests/vault/tests.py

@@ -248,9 +248,11 @@ class VaultTest(BaseVaultTest):
         if 'pause' not in vault_actions or 'resume' not in vault_actions:
             raise unittest.SkipTest("The version of charm-vault tested does "
                                     "not have pause/resume actions")
+        # this pauses and resumes the LEAD unit
         with self.pause_resume(['vault']):
             logging.info("Testing pause resume")
-        self.assertTrue(self.clients[0].hvac_client.seal_status['sealed'])
+        lead_client = vault_utils.extract_lead_unit_client(self.clients)
+        self.assertTrue(lead_client.hvac_client.seal_status['sealed'])
 
 
 if __name__ == '__main__':

zaza/openstack/charm_tests/vault/utils.py

@@ -173,6 +173,37 @@ def get_clients(units=None, cacert=None):
     return clients
 
 
+def extract_lead_unit_client(
+        clients=None, application_name='vault', cacert=None):
+    """Find the lead unit client.
+
+    This returns the lead unit client from a list of clients.  If no clients
+    are passed, then the clients are resolved using the cacert (if needed) and
+    the application_name.  The client is then matched to the lead unit.  If
+    clients are passed, but no leader is found in them, then the function
+    raises a RuntimeError.
+
+    :param clients: List of CharmVaultClient
+    :type clients: List[CharmVaultClient]
+    :param application_name: The application name
+    :type application_name: str
+    :param cacert: Path to CA cert used for vaults api cert.
+    :type cacert: str
+    :returns: The leader client
+    :rtype: CharmVaultClient
+    :raises: RuntimeError if the lead unit cannot be found
+    """
+    if clients is None:
+        units = zaza.model.get_app_ips('vault')
+        clients = get_clients(units, cacert)
+    lead_ip = zaza.model.get_lead_unit_ip(application_name)
+    for client in clients:
+        if client.addr == lead_ip:
+            return client
+    raise RuntimeError("Leader client not found for application: {}"
+                       .format(application_name))
+
+
 def is_initialized(client):
     """Check if vault is initialized.