celery: log an error for some deprecated config settings

dburi was dropped from templates in d34a59bfcebb1 and is no longer supported
in Celery 4.

celery.send.task.error.emails will no longer be supported in Celery 4 and was
just removed from the .ini template .

The "serialier" typo was fixed in 8169770a4f2c. It might bite people if they
keep using the wrong spelling.

kallithea/lib/celerypylons/__init__.py

@@ -1,58 +1,72
 # -*- coding: utf-8 -*-
 
 """
 Kallithea wrapper of Celery
 
 The Celery configuration is in the Kallithea ini file but must be converted to an
 entirely different format before Celery can use it.
 
 We read the configuration from tg.config at module import time. This module can
 thus not be imported in global scope but must be imported on demand in function
 scope after tg.config has been initialized.
 
 To make sure that the config really has been initialized, we check one of the
 mandatory settings.
 """
 
+import logging
+
 import celery
 import tg
 
 
 class CeleryConfig(object):
     CELERY_IMPORTS = ['kallithea.lib.celerylib.tasks']
     CELERY_ACCEPT_CONTENT = ['json']
     CELERY_RESULT_SERIALIZER = 'json'
     CELERY_TASK_SERIALIZER = 'json'
 
 
+desupported = set([
+    'celery.result.dburi',
+    'celery.result.serialier',
+    'celery.send.task.error.emails',
+])
+
+
+log = logging.getLogger(__name__)
+
+
 def celery_config(config):
     """Return Celery config object populated from relevant settings in a config dict, such as tg.config"""
 
     celery_config = CeleryConfig()
 
     PREFIXES = """ADMINS BROKER CASSANDRA CELERYBEAT CELERYD CELERYMON CELERY EMAIL SERVER""".split()
     LIST_PARAMS = """CELERY_IMPORTS CELERY_ACCEPT_CONTENT""".split()
 
     for config_key, config_value in sorted(config.items()):
+        if config_key in desupported and config_value:
+            log.error('Celery configuration setting %r is no longer supported', config_key)
         celery_key = config_key.replace('.', '_').upper()
         if celery_key.split('_', 1)[0] not in PREFIXES:
             continue
         if not isinstance(config_value, str):
             continue
         if celery_key in LIST_PARAMS:
             celery_value = config_value.split()
         elif config_value.isdigit():
             celery_value = int(config_value)
         elif config_value.lower() in ['true', 'false']:
             celery_value = config_value.lower() == 'true'
         else:
             celery_value = config_value
         setattr(celery_config, celery_key, celery_value)
     return celery_config
 
 
 def make_app():
     """Create celery app from the TurboGears configuration file"""
     app = celery.Celery()
     app.config_from_object(celery_config(tg.config))
     return app