Add a missing call to restore_configuration_files.

I accidentially removed the call when moving the backup functions
to the external script. It is intended to save the configuration,
so that at the restore phase one can just copy backup files.
Its primary intention was to save configuration files in the WAL-E
case (WAL-E just omits everything with .conf), but it is also
useful in the pg_basebackup case, which omits all symlinks, leaving
the cluster with .conf files symlinked in the broken state.

patroni/postgresql.py

@@ -485,19 +485,23 @@ recovery_target_timeline = 'latest'
 
     def save_configuration_files(self):
         """
-            copy postgresql.conf to postgresql.conf.backup to preserve it in the WAL-e backup.
-            see http://comments.gmane.org/gmane.comp.db.postgresql.wal-e/239
+            copy postgresql.conf to postgresql.conf.backup to be able to retrive configuration files
+            - originally stored as symlinks, those are normally skipped by pg_basebackup
+            - in case of WAL-E basebackup (see http://comments.gmane.org/gmane.comp.db.postgresql.wal-e/239)
         """
-        for f in self.configuration_to_save:
-            shutil.copy(f, f + '.backup')
+        try:
+            for f in self.configuration_to_save:
+                os.path.isfile(f) and shutil.copy(f, f + '.backup')
+        except:
+            logger.exception('unable to create backup copies of configuration files')
 
     def restore_configuration_files(self):
         """ restore a previously saved postgresql.conf """
         try:
             for f in self.configuration_to_save:
-                shutil.copy(f + '.backup', f)
+                not os.path.isfile(f) and os.path.isfile(f+'.backup') and shutil.copy(f + '.backup', f)
         except:
-            logger.exception('unable to restore configuration from WAL-E backup')
+            logger.exception('unable to restore configuration files from backup')
 
     def promote(self):
         if self.role == 'master':
@@ -585,6 +589,7 @@ recovery_target_timeline = 'latest'
                 raise PostgresException("Could not bootstrap master PostgreSQL")
         else:
             if self.sync_from_leader(current_leader):
+                self.restore_configuration_files()
                 self.write_recovery_conf(current_leader)
                 ret = self.start()
         return ret

tests/test_postgresql.py

@@ -19,6 +19,11 @@ from test_ha import false
 import subprocess
 
 
+def is_file_raise_on_backup(*args, **kwargs):
+    if args[0].endswith('.backup'):
+        raise Exception("foo")
+
+
 class MockCursor:
 
     def __init__(self, connection):
@@ -429,3 +434,15 @@ class TestPostgresql(unittest.TestCase):
         self.p.cleanup_archive_status()
         mock_unlink.assert_not_called()
         mock_remove.assert_not_called()
+
+    @patch('os.path.isfile', MagicMock(return_value=True))
+    @patch('shutil.copy', side_effect=Exception)
+    def test_save_configuration_files(self, mock_copy):
+        shutil.copy = mock_copy
+        self.p.save_configuration_files()
+
+    @patch('os.path.isfile', MagicMock(side_effect=is_file_raise_on_backup))
+    @patch('shutil.copy', side_effect=Exception)
+    def test_restore_configuration_files(self, mock_copy):
+        shutil.copy = mock_copy
+        self.p.restore_configuration_files()