templates/layout: Fallback to django auth when keycloak is not used

This restores the login link to use basic django authentication when
Keycloak is not used, for instance in the docker environment.

swh/web/templates/layout.html

@@ -129,6 +129,12 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
               {% else %}
                 <a href="{% url 'oidc-login' %}">login</a>
               {% endif %}
+            {% else %}
+              {% if request.path != logout_url %}
+                <a href="{% url 'login' %}?next={{ request.build_absolute_uri }}">login</a>
+              {% else %}
+                <a href="{% url 'login' %}">login</a>
+              {% endif %}
             {% endif %}
           </li>
         </ul>

swh/web/tests/test_templates.py

@@ -6,7 +6,7 @@
 import random
 
 from swh.web.common.utils import reverse
-from swh.web.config import STAGING_SERVER_NAMES
+from swh.web.config import STAGING_SERVER_NAMES, get_config
 from swh.web.tests.django_asserts import assert_contains, assert_not_contains
 from swh.web.tests.utils import check_http_get_response
 
@@ -23,3 +23,20 @@ def test_layout_with_staging_ribbon(client):
         client, url, status_code=200, server_name=random.choice(STAGING_SERVER_NAMES),
     )
     assert_contains(resp, "swh-corner-ribbon")
+
+
+def test_layout_with_oidc_auth_enabled(client):
+    url = reverse("swh-web-homepage")
+    resp = check_http_get_response(client, url, status_code=200)
+    assert_contains(resp, reverse("oidc-login"))
+
+
+def test_layout_without_oidc_auth_enabled(client, mocker):
+    config = get_config()
+    config["keycloak"]["server_url"] = ""
+    mock_get_config = mocker.patch("swh.web.common.utils.get_config")
+    mock_get_config.return_value = config
+
+    url = reverse("swh-web-homepage")
+    resp = check_http_get_response(client, url, status_code=200)
+    assert_contains(resp, reverse("login"))