Allow custom pager support in patronictl edit-config (#1696)

Fixes #1695

patroni/ctl.py

@@ -7,7 +7,6 @@ import codecs
 import datetime
 import dateutil.parser
 import dateutil.tz
-import cdiff
 import copy
 import difflib
 import io
@@ -34,6 +33,10 @@ from patroni.request import PatroniRequest
 from patroni.version import __version__
 from prettytable import ALL, FRAME, PrettyTable
 from six.moves.urllib_parse import urlparse
+try:
+    from ydiff import markup_to_pager, PatchStream
+except ImportError:  # pragma: no cover
+    from cdiff import markup_to_pager, PatchStream
 
 CONFIG_DIR_PATH = click.get_app_dir('patroni')
 CONFIG_FILE_PATH = os.path.join(CONFIG_DIR_PATH, 'patronictl.yaml')
@@ -1086,7 +1089,14 @@ def show_diff(before_editing, after_editing):
             side_by_side = False
             width = 80
             tab_width = 8
-        cdiff.markup_to_pager(cdiff.PatchStream(buf), opts)
+            wrap = True
+            if find_executable('less'):
+                pager = None
+            else:
+                pager = 'more.com' if sys.platform == 'win32' else 'more'
+            pager_options = None
+
+        markup_to_pager(PatchStream(buf), opts)
     else:
         for line in unified_diff:
             click.echo(line.rstrip('\n'))

requirements.txt

@@ -10,4 +10,4 @@ prettytable>=0.7
 python-dateutil
 pysyncobj>=0.3.5
 psutil>=2.0.0
-cdiff
+ydiff>=1.2.0

tests/test_ctl.py

@@ -561,7 +561,7 @@ class TestCtl(unittest.TestCase):
         self.assertRaises(PatroniCtlException, apply_config_changes, before_editing, config, ['a'])
 
     @patch('sys.stdout.isatty', return_value=False)
-    @patch('cdiff.markup_to_pager')
+    @patch('patroni.ctl.markup_to_pager')
     def test_show_diff(self, mock_markup_to_pager, mock_isatty):
         show_diff("foo:\n  bar: 1\n", "foo:\n  bar: 2\n")
         mock_markup_to_pager.assert_not_called()
@@ -570,6 +570,9 @@ class TestCtl(unittest.TestCase):
         show_diff("foo:\n  bar: 1\n", "foo:\n  bar: 2\n")
         mock_markup_to_pager.assert_called_once()
 
+        with patch('patroni.ctl.find_executable', Mock(return_value=None)):
+            show_diff("foo:\n  bar: 1\n", "foo:\n  bar: 2\n")
+
         # Test that unicode handling doesn't fail with an exception
         show_diff(b"foo:\n  bar: \xc3\xb6\xc3\xb6\n".decode('utf-8'),
                   b"foo:\n  bar: \xc3\xbc\xc3\xbc\n".decode('utf-8'))