title: Horizon Access - Unable to create a new session key. It is likely that the cache is unavailable
body: <p>I tried to access Horizon as recommended <a href="https://microstack.run/docs/" rel="nofollow noreferrer">here</a>, through the IP <code>10.20.20.1</code> and <code>admin</code> user, and received the following runtime error:</p>
  <pre><code>Request Method: | POST
  -- | --
  http://10.20.20.1/auth/login/
  2.0.13
  RuntimeError
  Unable to create a new session key. It is likely that the cache is unavailable.
  /snap/microstack/196/lib/python3.6/site-packages/django/contrib/sessions/backends/cache.py in create, line 51
  /snap/microstack/196/bin/uwsgi
  3.6.9
  ['.',  '',  '/snap/microstack/196/usr/lib/python36.zip',  '/snap/microstack/196/usr/lib/python3.6',  
  '/snap/microstack/196/usr/lib/python3.6/lib-dynload',  '/snap/microstack/196/usr/lib/python3/dist-packages',  
  '/snap/microstack/196/lib/python3.6/site-packages',  '/snap/microstack/196/lib/python3.6/site-packages/openstack_dashboard']
  Mon, 17 Aug 2020 12:42:48 +0000
  </code></pre>
  <p>The expected result would be a successful login.</p>