An Error Occurs During the Horizon WebUI Login

Symptom

Failed to log in to the Horizon WebUI.

Key Process and Cause Analysis

The following log information is displayed in /var/log/httpd/openstack-dashboard-error_log:

 [wsgi:error] [pid 600967:tid 601105] [remote 192.255.5.10:13113] INFO openstack_auth.forms Login successful for user "admin" using domain "default", remote address 192.255.5.10.
 [wsgi:error] [pid 600967:tid 601105] [remote 192.255.5.10:13113] ERROR django.request Internal Server Error: /dashboard/auth/login/
......
 [wsgi:error] [pid 600967:tid 601105] [remote 192.255.5.10:13113] RuntimeError: Unable to create a new session key. It is likely that the cache is unavailable.

According to the logs, the login is successful, but the page is not properly displayed. The session cache is abnormal.

Conclusion and Solution

1. Check whether the following configuration in the /etc/openstack-dashboard/local_settings file is correct:

   OPENSTACK_HOST = "controller"  
   SESSION_ENGINE = 'django.contrib.sessions.backends.cache'  
   CACHES = {  
   'default': {
          'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
          'LOCATION': 'controller:11211',
         }  
   }

   controller is the hostname of the controller node.

2. Check whether the following configuration in the /etc/sysconfig/memcached file is correct:

   OPTIONS="-l 127.0.0.1,::1,controller"

   controller is the hostname of the controller node.

3. Restart the service.

   1	systemctl restart httpd.service memcached.service