Add autoscaler information on stats inspect command (#4897)

* Add autoscaler info when returning inspect.stats()

* Add testing for autoscaler boot step info and fix flake8 warning

* Fix docstring

celery/worker/autoscale.py

@@ -57,6 +57,10 @@ class WorkerComponent(bootsteps.StartStopStep):
             w.autoscaler.keepalive, w.autoscaler.maybe_scale,
         )
 
+    def info(self, w):
+        """Return `Autoscaler` info."""
+        return {'autoscaler': w.autoscaler.info()}
+
 
 class Autoscaler(bgThread):
     """Background thread to autoscale pool workers."""

t/unit/worker/test_autoscale.py

@@ -59,6 +59,18 @@ class test_WorkerComponent:
         w.register_with_event_loop(parent, Mock(name='loop'))
         assert parent.consumer.on_task_message
 
+    def test_info_without_event_loop(self):
+        parent = Mock(name='parent')
+        parent.autoscale = True
+        parent.max_concurrency = '10'
+        parent.min_concurrency = '2'
+        parent.use_eventloop = False
+        w = autoscale.WorkerComponent(parent)
+        w.create(parent)
+        info = w.info(parent)
+        assert 'autoscaler' in info
+        assert parent.autoscaler_cls().info.called
+
 
 class test_Autoscaler: