Fix differing bootstrap uuids

When is_bootstrapped is consulted it was returning a false negative.
When the leader node is bootstrapped it sets the uuid via leader_set,
but during a leader-settings-changed hook when the non-leader should
be picking up the uuid it was checking relation data instead which will
be way behind the curve. This is a vestigial block of code
pre-leadership.

Leader settings get set much earlier than relation data. This change
consults leader_get rather than the relation. We also make sure the
mysqld.cnf file is rendered on a leader-settings-changed hook.

Change-Id: I95e56bd28152c934f413025a22dd6821b2ad8e94
Closes-Bug: #1738896

hooks/percona_hooks.py

@@ -730,8 +730,8 @@ def ha_relation_changed():
 def leader_settings_changed():
     '''Re-trigger install once leader has seeded passwords into install'''
     install_percona_xtradb_cluster()
-    # Notify any changes to data in leader storage
-    update_shared_db_rels()
+    # Need to render the template files
+    config_changed()
     log('leader-settings-changed', level='DEBUG')
     try:
         update_bootstrap_uuid()

hooks/percona_utils.py

@@ -76,6 +76,8 @@ SEEDED_MARKER = "{data_dir}/seeded"
 HOSTS_FILE = '/etc/hosts'
 DEFAULT_MYSQL_PORT = 3306
 
+WSREP_FILE = "/etc/mysql/percona-xtradb-cluster.conf.d/wsrep.cnf"
+
 # NOTE(ajkavanagh) - this is 'required' for the pause/resume code for
 # maintenance mode, but is currently not populated as the
 # charm_check_function() checks whether the unit is working properly.
@@ -407,23 +409,15 @@ def is_bootstrapped():
 
     @returns boolean
     """
-    uuids = []
-    rids = relation_ids('cluster') or []
-    for rid in rids:
-        units = related_units(rid)
-        units.append(local_unit())
-        for unit in units:
-            id = relation_get('bootstrap-uuid', unit=unit, rid=rid)
-            if id:
-                uuids.append(id)
-
-    if uuids:
-        if len(set(uuids)) > 1:
-            log("Found inconsistent bootstrap uuids - %s" % (uuids), WARNING)
 
+    # Is the leader bootstrapped?
+    # Leader settings happen long before relation settings.
+    if leader_get('bootstrap-uuid'):
+        log("Leader is bootstrapped uuid: {}".format(
+            leader_get('bootstrap-uuid')), WARNING)
         return True
-
-    return False
+    else:
+        return False
 
 
 def bootstrap_pxc():