Missing a queue name upon receiving a task event

src/exporter.py

@@ -1,4 +1,5 @@
 # pylint: disable=protected-access,,attribute-defined-outside-init
+from functools import lru_cache
 import json
 import re
 import sys
@@ -7,7 +8,7 @@
 from typing import Callable, Optional
 
 from celery import Celery
-from celery.events.state import State  # type: ignore
+from celery.events.state import State, Task  # type: ignore
 from celery.utils import nodesplit  # type: ignore
 from celery.utils.time import utcoffset  # type: ignore
 from kombu.exceptions import ChannelError  # type: ignore
@@ -141,6 +142,27 @@ def scrape(self):
             self.track_timed_out_workers()
         self.track_queue_metrics()
 
+    @lru_cache(maxsize=32)
+    def find_queue_by_task(self, target: Task) -> str:
+        """Provider a queue name based on metadata coming from eiether a worker or a task being processed by it"""
+
+        try:
+            queue_name = None
+            # https://github.com/celery/celery/issues/5321
+            # task_info = self.app.control.inspect().query_task(task.id)
+            # As the received tasks are considered as active ones
+            task_set = self.app.control.inspect().registered().get(target.hostname)
+            task_info = [task for task in task_set if task['id'] == target.id].pop()
+            queue_name = task_info["delivery_info"]["routing_key"]
+        except TimeoutError as error:
+            # the broker doesn't respond
+            logger.error(f"Couldn't fetch the task info of {target.id}: {error.strerror}")
+        except IndexError as error:
+            # couldn't find the target task by id
+            # the dictionary path is missing
+            logger.warning(f"Couldn't find the target task by its id: {target.id}")
+        return queue_name
+
     def forget_worker(self, hostname):
         if hostname in self.worker_last_seen:
             self.celery_worker_up.labels(hostname=hostname).set(0)
@@ -263,7 +285,9 @@ def track_task_event(self, event):
         labels = {
             "name": task.name,
             "hostname": get_hostname(task.hostname),
-            "queue_name": getattr(task, "queue", "celery"),
+            # queue property should be available when a task is called with a passed queue name
+            # otherwise, we need to query its meta using the celery instance
+            "queue_name": getattr(task, "queue", self.find_queue_by_task(task) or "celery"),
         }
         if event["type"] == "task-sent" and self.generic_hostname_task_sent_metric:
             labels["hostname"] = "generic"