Make tyrant backend load without TT_HOST/TT_PORT config set (delays the ImproperlyConfigured until backend initialization)

celery/backends/tyrant.py

@@ -15,24 +15,27 @@ try:
 except ImportError:
     import pickle
 
-TT_HOST = getattr(settings, "TT_HOST", None)
-TT_PORT = getattr(settings, "TT_PORT", None)
-
-if not TT_HOST or not TT_PORT:
-    raise ImproperlyConfigured(
-            "To use the Tokyo Tyrant backend, you have to "
-            "set the TT_HOST and TT_PORT settings in your settings.py")
-else:
-    def get_server():
-        return pytyrant.PyTyrant.open(TT_HOST, TT_PORT)
     
 
 class Backend(BaseBackend):
     """Tokyo Cabinet based task backend store."""
+    tyrant_host = None
+    tyrant_port = None
 
     def __init__(self, *args, **kwargs):
+        self.tyrant_host = kwargs.get("tyrant_host", 
+                            getattr(settings, "TT_HOST", self.tyrant_host))
+        self.tyrant_port = kwargs.get("tyrant_port",
+                            getattr(settings, "TT_PORT", self.tyrant_port))
+        if not self.tyrant_host or not self.tyrant_port:
+            raise ImproperlyConfigured(
+                "To use the Tokyo Tyrant backend, you have to "
+                "set the TT_HOST and TT_PORT settings in your settings.py")
         super(Backend, self).__init__(*args, **kwargs)
         self._cache = {}
+    
+    def get_server(self):
+        return pytyrant.PyTyrant.open(self.tyrant_host, self.tyrant_port)
 
     def _cache_key(self, task_id):
         return "celery-task-meta-%s" % task_id
@@ -41,7 +44,7 @@ class Backend(BaseBackend):
         """Store task result and status."""
         result = self.prepare_result(result)
         meta = {"status": status, "result": pickle.dumps(result)}
-        get_server()[self._cache_key(task_id)] = serialize(meta)
+        self.get_server()[self._cache_key(task_id)] = serialize(meta)
 
     def get_status(self, task_id):
         """Get the status for a task."""
@@ -58,7 +61,7 @@ class Backend(BaseBackend):
     def _get_task_meta_for(self, task_id):
         if task_id in self._cache:
             return self._cache[task_id]
-        meta = get_server().get(self._cache_key(task_id))
+        meta = self.get_server().get(self._cache_key(task_id))
         if not meta:
             return {"status": "PENDING", "result": None}
         meta = deserialize(meta)