Made the adress of the database dynamic

With dynamic, i mean that it is retreived from the database host

roles/keystone/templates/keystone.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Openstack Keystone Container
+After=docker.service
+Requires=docker.service
+
+[Service]
+TimeoutStartSec=0
+Restart=always
+ExecStartPre=-/usr/bin/docker stop %n
+ExecStartPre=-/usr/bin/docker rm %n
+ExecStart=/usr/bin/docker run --name %n \
+  --add-host=mariadb:{{ hostvars[groups['databases'][0]]['ansible_default_ipv4']['address'] }} \
+  -p 5001:5000 -p 35357:35357 \
+  -v /srv/keystone/fernet-keys:/etc/keystone/fernet-keys \
+  hpc/keystone
+
+[Install]
+WantedBy=multi-user.target