Dump frontend config JSON with an indent

Fixes gh-7857

IPython/config/manager.py

@@ -1,99 +1,99 b''
 """Manager to read and modify config data in JSON files.
 """
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 import errno
 import io
 import json
 import os
 
 from IPython.config import LoggingConfigurable
 from IPython.utils.path import locate_profile
 from IPython.utils.py3compat import PY3
 from IPython.utils.traitlets import Unicode
 
 
 def recursive_update(target, new):
     """Recursively update one dictionary using another.
 
     None values will delete their keys.
     """
     for k, v in new.items():
         if isinstance(v, dict):
             if k not in target:
                 target[k] = {}
             recursive_update(target[k], v)
             if not target[k]:
                 # Prune empty subdicts
                 del target[k]
 
         elif v is None:
             target.pop(k, None)
 
         else:
             target[k] = v
 
 
 class BaseJSONConfigManager(LoggingConfigurable):
     """General config manager 
     
     Deals with persisting/storing config in a json file
     in IPython profile
     """
 
     profile_dir = Unicode()
     def _profile_dir_default(self):
         return locate_profile()
 
     @property
     def config_dir(self):
         return self._config_dir()
 
     def _config_dir(self):
         return self.profile_dir
 
     def ensure_config_dir_exists(self):
         try:
             os.mkdir(self.config_dir, 0o755)
         except OSError as e:
             if e.errno != errno.EEXIST:
                 raise
 
     def file_name(self, section_name):
         return os.path.join(self.config_dir, section_name+'.json')
 
     def get(self, section_name):
         """Retrieve the config data for the specified section.
 
         Returns the data as a dictionary, or an empty dictionary if the file
         doesn't exist.
         """
         filename = self.file_name(section_name)
         if os.path.isfile(filename):
             with io.open(filename, encoding='utf-8') as f:
                 return json.load(f)
         else:
             return {}
 
     def set(self, section_name, data):
         """Store the given config data.
         """
         filename = self.file_name(section_name)
         self.ensure_config_dir_exists()
 
         if PY3:
             f = io.open(filename, 'w', encoding='utf-8')
         else:
             f = open(filename, 'wb')
         with f:
-            json.dump(data, f)
+            json.dump(data, f, indent=2)
 
     def update(self, section_name, new_data):
         """Modify the config section by recursively updating it with new_data.
 
         Returns the modified config data as a dictionary.
         """
         data = self.get(section_name)
         recursive_update(data, new_data)
         self.set(section_name, data)
         return data

IPython/html/services/config/manager.py

@@ -1,14 +1,14 b''
 """Manager to read and modify frontend config data in JSON files.
 """
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import os
 
 from IPython.config.manager import BaseJSONConfigManager
 
 class ConfigManager(BaseJSONConfigManager):
-    """Config Manager use for storin Javascript side config"""
+    """Config Manager used for storing notebook frontend config"""
 
     def _config_dir(self):
         return os.path.join(self.profile_dir, 'nbconfig')