feat!: Remove django-admin default login (#29876)

* feat!: Remove django-admin default login

cms/djangoapps/contentstore/tests/test_admin.py

@@ -0,0 +1,32 @@
+"""
+Tests that verify that the admin view loads.
+
+This is not inside a django app because it is a global property of the system.
+"""
+import ddt
+from django.test import TestCase
+from django.urls import reverse
+from edx_toggles.toggles.testutils import override_waffle_flag
+
+from openedx.core.djangoapps.user_authn.config.waffle import ADMIN_AUTH_REDIRECT_TO_LMS
+
+
+@ddt.ddt
+class TestAdminView(TestCase):
+    """
+    Tests of the admin view.
+    """
+    @override_waffle_flag(ADMIN_AUTH_REDIRECT_TO_LMS, True)
+    @ddt.data('/admin/', '/admin/login', reverse('admin:login'))
+    def test_admin_login_redirect(self, admin_url):
+        """Admin login will redirect towards the site login page."""
+        response = self.client.get(admin_url, follow=True)
+        assert any('/login/edx-oauth2/?next=' in r[0] for r in response.redirect_chain)
+
+    def test_admin_login_default(self):
+        """Without flag Admin login will redirect towards the admin default login page."""
+        response = self.client.get('/admin/', follow=True)
+        assert response.status_code == 200
+        self.assertIn('/admin/login/?next=/admin/', response.redirect_chain[0])
+        assert len(response.redirect_chain) == 1
+        assert response.template_name == ['admin/login.html']

cms/djangoapps/contentstore/views/public.py

@@ -7,12 +7,17 @@ from django.conf import settings
 from django.shortcuts import redirect
 from urllib.parse import quote_plus  # lint-amnesty, pylint: disable=wrong-import-order
 from waffle.decorators import waffle_switch
+from django.contrib import admin
 
 from common.djangoapps.edxmako.shortcuts import render_to_response
+from openedx.core.djangoapps.user_authn.config.waffle import ADMIN_AUTH_REDIRECT_TO_LMS
 
 from ..config import waffle
 
-__all__ = ['register_redirect_to_lms', 'login_redirect_to_lms', 'howitworks', 'accessibility']
+__all__ = [
+    'register_redirect_to_lms', 'login_redirect_to_lms', 'howitworks', 'accessibility',
+    'redirect_to_lms_login_for_admin',
+]
 
 
 def register_redirect_to_lms(request):
@@ -39,6 +44,16 @@ def login_redirect_to_lms(request):
     return redirect(login_url)
 
 
+def redirect_to_lms_login_for_admin(request):
+    """
+    This view redirect the admin/login url to the site's login page.
+    """
+    if ADMIN_AUTH_REDIRECT_TO_LMS.is_enabled():
+        return redirect('/login?next=/admin')
+    else:
+        return admin.site.login(request)
+
+
 def _build_next_param(request):
     """ Returns the next param to be used with login or register. """
     next_url = request.GET.get('next')