feat(utils): New is_database_replica_setup utility (#100)

* Tell whether any database replica is setup

* Cache

Author: emyller

src/common/core/utils.py

@@ -4,7 +4,7 @@
 import random
 from functools import lru_cache
 from itertools import cycle
-from typing import Iterator, Literal, NotRequired, TypedDict, TypeVar
+from typing import Iterator, Literal, NotRequired, TypedDict, TypeVar, get_args
 
 from django.conf import settings
 from django.contrib.auth import get_user_model
@@ -130,6 +130,14 @@ def get_file_contents(file_path: str) -> str | None:
         return None
 
 
+@lru_cache()
+def is_database_replica_setup() -> bool:
+    """Checks if any database replica is set up"""
+    return any(
+        name for name in connections if name.startswith(get_args(ReplicaNamePrefix))
+    )
+
+
 def using_database_replica(
     manager: ManagerType,
     replica_prefix: ReplicaNamePrefix = "replica_",

tests/unit/common/core/test_utils.py

@@ -15,6 +15,7 @@
     get_version_info,
     get_versions_from_manifest,
     has_email_provider,
+    is_database_replica_setup,
     is_enterprise,
     is_oss,
     is_saas,
@@ -204,6 +205,37 @@ def test_get_version__invalid_file_contents__returns_unknown(
     assert result == "unknown"
 
 
+@pytest.mark.parametrize(
+    ["database_names", "expected"],
+    [
+        ({"default"}, False),
+        ({"default", "another_database_with_'replica'_in_its_name"}, False),
+        ({"default", "task_processor"}, False),
+        ({"default", "replica_1"}, True),
+        ({"default", "replica_1", "replica_2"}, True),
+        ({"default", "cross_region_replica_1"}, True),
+        ({"default", "replica_1", "cross_region_replica_1"}, True),
+    ],
+)
+def test_is_database_replica_setup__tells_whether_any_replica_is_present(
+    database_names: list[str],
+    expected: bool,
+    mocker: MockerFixture,
+) -> None:
+    # Given
+    is_database_replica_setup.cache_clear()
+    mocker.patch(
+        "common.core.utils.connections",
+        {name: connections["default"] for name in database_names},
+    )
+
+    # When
+    result = is_database_replica_setup()
+
+    # Then
+    assert result is expected
+
+
 @pytest.mark.django_db(databases="__all__")
 def test_using_database_replica__no_replicas__points_to_default(
     django_assert_num_queries: DjangoAssertNumQueries,