Conditionally include Redis connection information

Redis is only used when cache is enabled or RQ tasking is used. In other
cases, the connection is not needed. We've changed the Foreman installer
to only install Redis if needed, just to stop wasting resources[1].
However, this leads to warnings.

This PR changes the status view to only include Redis if it's used.

[1]: theforeman/puppet-pulpcore@7a5543b

closes #9070
https://pulp.plan.io/issues/9070

CHANGES/9070.bugfix

@@ -0,0 +1,2 @@
+Set Redis connection information in status to null unless it's used. Redis is
+needed for RQ tasking or content caching.

pulpcore/app/serializers/status.py

@@ -74,6 +74,9 @@ class StatusSerializer(serializers.Serializer):
         help_text=_("Database connection information")
     )
 
-    redis_connection = RedisConnectionSerializer(help_text=_("Redis connection information"))
+    redis_connection = RedisConnectionSerializer(
+        required=False,
+        help_text=_("Redis connection information"),
+    )
 
     storage = StorageSerializer(required=False, help_text=_("Storage information"))

pulpcore/app/views/status.py

@@ -57,7 +57,11 @@ def get(self, request):
         for app in pulp_plugin_configs():
             versions.append({"component": app.label, "version": app.version})
 
-        redis_status = {"connected": self._get_redis_conn_status()}
+        if settings.CACHE_ENABLED or not settings.USE_NEW_WORKER_TYPE:
+            redis_status = {"connected": self._get_redis_conn_status()}
+        else:
+            redis_status = None
+
         db_status = {"connected": self._get_db_conn_status()}
 
         try:

pulpcore/tests/functional/api/test_status.py

@@ -1,6 +1,7 @@
 """Test the status page."""
 import unittest
 
+from django.test import override_settings
 from jsonschema import validate
 from pulp_smash import api, cli, config, utils
 from pulp_smash.pulp3.constants import STATUS_PATH
@@ -91,10 +92,20 @@ def verify_get_response(self, status):
         """
         validate(status, self.status_response)
         self.assertTrue(status["database_connection"]["connected"])
+        self.assertIsNotNone(status["redis_connection"])
         self.assertTrue(status["redis_connection"]["connected"])
         self.assertNotEqual(status["online_workers"], [])
         self.assertNotEqual(status["versions"], [])
         if self.storage == "pulpcore.app.models.storage.FileSystem":
             self.assertIsNotNone(status["storage"])
         else:
             self.assertIsNone(status["storage"])
+
+    @override_settings(CACHE_ENABLED=False, USE_NEW_WORKER_TYPE=True)
+    def verify_get_response_without_redis(self, status):
+        """Verify the response to an HTTP GET call when Redis is not used.
+
+        Verify that redis_connection is null
+        """
+        validate(status, self.status_response)
+        self.assertIsNone(status["redis_connection"])