[#2429] config_option_show action.

Sysadmins can call this action with a key (eg. 'ckan.site_title') to
retrieve a config value. The value is returned either from the
system_info table of the database, or secondly, from the config object
as defined in the ini file. Only config options in the schema
whitelisted as editable will be returned. Non-editable options, or non
existing options, will return a ValidationError.

ckan/logic/action/get.py

@@ -3361,3 +3361,43 @@ def help_show(context, data_dict):
         raise NotFound('Action function not found')
 
     return function.__doc__
+
+
+def config_option_show(context, data_dict):
+    '''Show the current value of a particular configuration option.
+
+    Only return config options that can be updated with the
+    `config_option_update` action.
+
+    :param id: The configuration option key
+    :type id: string
+
+    :returns: The value of the config option from either the system_info table
+        or ini file.
+    :rtype: string
+
+    :raises: :class:`ckan.logic.ValidationError`: if config option is not in
+        the schema (whitelisted as editable).
+    '''
+
+    model = context['model']
+
+    _check_access('config_option_show', context, data_dict)
+
+    key = _get_or_bust(data_dict, 'key')
+
+    schema = ckan.logic.schema.default_show_configuration_schema()
+
+    # Only return whitelisted keys
+    if key not in schema:
+        raise ValidationError(
+            'Configuration option \'{0}\' can not be shown'.format(key))
+
+    # return the value from system_info or config
+    default_value = config.get(key, None)
+    if key in schema.keys():
+        value = model.get_system_info(key, default=default_value)
+    else:
+        value = default_value
+
+    return value

ckan/logic/auth/get.py

@@ -309,3 +309,8 @@ def request_reset(context, data_dict):
 
 def help_show(context, data_dict):
     return {'success': True}
+
+
+def config_option_show(context, data_dict):
+    '''Show configuration option. Only sysadmins.'''
+    return {'success': False}

ckan/logic/schema.py

@@ -679,3 +679,8 @@ def default_update_configuration_schema():
         validators.insert(0, ignore_missing)
 
     return schema
+
+
+def default_show_configuration_schema():
+    schema = default_update_configuration_schema()
+    return schema

ckan/tests/config/test_environment.py

@@ -55,7 +55,7 @@ def test_update_config_env_vars(self):
                                'my-site')
 
     def test_update_config_db_url_precidence(self):
-        '''CKAN_SQLALCHEMY_URL in the env takes precidence over CKAN_DB'''
+        '''CKAN_SQLALCHEMY_URL in the env takes precedence over CKAN_DB'''
         os.environ.setdefault('CKAN_DB', 'postgresql://mydeprectatesqlurl/')
         os.environ.setdefault('CKAN_SQLALCHEMY_URL',
                               'postgresql://mynewsqlurl/')

ckan/tests/logic/action/test_get.py

@@ -2,7 +2,6 @@
 
 import ckan.logic as logic
 import ckan.plugins as p
-import ckan.lib.search as search
 import ckan.tests.helpers as helpers
 import ckan.tests.factories as factories
 
@@ -1487,6 +1486,37 @@ def test_help_show_not_found(self):
             helpers.call_action, 'help_show', name=function_name)
 
 
+class TestConfigOptionShow(helpers.FunctionalTestBase):
+
+    @helpers.change_config('ckan.site_title', 'My Test CKAN')
+    def test_config_option_show_in_config_not_in_db(self):
+        '''config_option_show returns value from config when value on in
+        system_info table.'''
+
+        title = helpers.call_action('config_option_show',
+                                    key='ckan.site_title')
+        nose.tools.assert_equal(title, 'My Test CKAN')
+
+    @helpers.change_config('ckan.site_title', 'My Test CKAN')
+    def test_config_option_show_in_config_and_in_db(self):
+        '''config_option_show returns value from db when value is in both
+        config and system_info table.'''
+
+        factories.SystemInfo(key='ckan.site_title', value='Site Title in DB')
+
+        title = helpers.call_action('config_option_show',
+                                    key='ckan.site_title')
+        nose.tools.assert_equal(title, 'Site Title in DB')
+
+    @helpers.change_config('ckan.not.editable', 'My non editable option')
+    def test_config_option_show_not_whitelisted_key(self):
+        '''config_option_show raises exception if key is not a whitelisted
+        config option.'''
+
+        nose.tools.assert_raises(logic.ValidationError, helpers.call_action,
+                                 'config_option_show', key='ckan.not.editable')
+
+
 def remove_pseudo_users(user_list):
     pseudo_users = set(('logged_in', 'visitor'))
     user_list[:] = [user for user in user_list