Merge pull request #232 from zalando/bugfix/pg_rewind

Start readonly when holding leader lock

patroni/postgresql.py

@@ -729,14 +729,18 @@ class Postgresql(object):
             return True
 
         change_role = self.role == 'master'
-        self._need_rewind = self._need_rewind or change_role and self.can_rewind
+
+        if leader and leader.name == self.name:
+            self._need_rewind = False
+            member = None
+            if self.is_running():
+                return
+        else:
+            self._need_rewind = self._need_rewind or change_role and self.can_rewind
 
         if self._need_rewind:
             logger.info("set the rewind flag after demote")
 
-            if leader and leader.name == self.name:
-                return logger.info('Can not rewind from myself')
-
             if self.is_running():
                 stopped = self.stop()
                 self.set_role('unknown')

tests/test_postgresql.py

@@ -257,13 +257,13 @@ class TestPostgresql(unittest.TestCase):
         with patch.object(Postgresql, 'check_recovery_conf', Mock(return_value=True)):
             self.assertTrue(self.p.follow(None, None))  # nothing to do, recovery.conf has good primary_conninfo
 
+        self.p.follow(self.me, self.me)  # follow is called when the node is holding leader lock
+
         with patch.object(Postgresql, 'restart', Mock(return_value=False)):
             self.p.set_role('replica')
             self.p.follow(None, None)  # restart without rewind
             self.p.set_role('master')
 
-        self.p.follow(self.leader, self.me)  # Can not rewind from myself
-
         with patch.object(Postgresql, 'stop', Mock(return_value=False)):
             self.p.follow(self.leader, self.leader)  # failed to stop postgres