Fixed #8500 -- Allowed overriding the default admin site instance.

2 files changed, 13 insertions, 2 deletions

diff --git a/django/contrib/admin/apps.py b/django/contrib/admin/apps.py
index df7d669ab0..36c157683d 100644
--- a/django/contrib/admin/apps.py
+++ b/django/contrib/admin/apps.py
@@ -7,6 +7,7 @@ from django.utils.translation import gettext_lazy as _
 class SimpleAdminConfig(AppConfig):
     """Simple AppConfig which does not do automatic discovery."""
 
+    default_site = 'django.contrib.admin.sites.AdminSite'
     name = 'django.contrib.admin'
     verbose_name = _("Administration")
 
diff --git a/django/contrib/admin/sites.py b/django/contrib/admin/sites.py
index a3871fb534..f7d0ac0fbc 100644
--- a/django/contrib/admin/sites.py
+++ b/django/contrib/admin/sites.py
@@ -9,6 +9,8 @@ from django.db.models.base import ModelBase
 from django.http import Http404, HttpResponseRedirect
 from django.template.response import TemplateResponse
 from django.urls import NoReverseMatch, reverse
+from django.utils.functional import LazyObject
+from django.utils.module_loading import import_string
 from django.utils.text import capfirst
 from django.utils.translation import gettext as _, gettext_lazy
 from django.views.decorators.cache import never_cache
@@ -518,6 +520,14 @@ class AdminSite:
         ], context)
 
 
+class DefaultAdminSite(LazyObject):
+    def _setup(self):
+        AdminSiteClass = import_string(apps.get_app_config('admin').default_site)
+        self._wrapped = AdminSiteClass()
+
+
 # This global object represents the default admin site, for the common case.
-# You can instantiate AdminSite in your own code to create a custom admin site.
-site = AdminSite()
+# You can provide your own AdminSite using the (Simple)AdminConfig.default_site
+# attribute. You can also instantiate AdminSite in your own code to create a
+# custom admin site.
+site = DefaultAdminSite()