Use explicit flag to detect database in container during tests

Author: Photonios

.circleci/config.yml

@@ -45,6 +45,7 @@ commands:
           command: tox --listenvs | grep ^py<< parameters.pyversion >> | circleci tests split | xargs -n 1 tox -e
           environment:
             DATABASE_URL: 'postgres://psqlextra:psqlextra@localhost:5432/psqlextra'
+            DATABASE_IN_CONTAINER: 'true'
 
 jobs:
   test-python36:

settings.py

@@ -43,3 +43,5 @@ def _parse_db_url(url: str):
 
 USE_TZ = True
 TIME_ZONE = 'UTC'
+
+DATABASE_IN_CONTAINER = os.environ.get('DATABASE_IN_CONTAINER') == 'true'

tests/conftest.py

@@ -34,10 +34,6 @@ def django_db_setup(django_db_setup, django_db_blocker):
 
     with django_db_blocker.unblock():
         qn = connection.ops.quote_name
-
-        db_user = settings.DATABASES[connection.alias]["USER"]
-        db_hostname = settings.DATABASES[connection.alias]["HOST"]
-
         with tempfile.TemporaryDirectory() as temp_dir:
             with connection.cursor() as cursor:
                 # If the database is remote, like in a CI environment, make
@@ -46,14 +42,7 @@ def django_db_setup(django_db_setup, django_db_blocker):
                 #
                 # Note that this only typically works in CI environments
                 # where we have utter control to execute arbitary commands.
-                if db_user or (
-                    db_hostname
-                    and db_hostname
-                    not in (
-                        "127.0.0.1",
-                        "localhost",
-                    )
-                ):
+                if settings.DATABASE_IN_CONTAINER:
                     cursor.execute(
                         f"COPY (select 1) TO PROGRAM 'mkdir --mode=777 -p {temp_dir}'"
                     )