[nova] AuthToken is marked invalid in memcache

Issue is related to nova in case of using REST (that includes Horizon): it's impossible to use auth-token several times.

Logs:

Nov 13 06:58:49 controller-1461 nova keystoneclient.middleware.auth_token DEBUG Token validation failure.
Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/keystoneclient/middleware/auth_token.py", line 684, in _validate_u
ser_token
    cached = self._cache_get(token_id)
  File "/usr/lib/python2.6/site-packages/keystoneclient/middleware/auth_token.py", line 898, in _cache_get
    raise InvalidUserToken('Token authorization failed')
InvalidUserToken: Token authorization failed
Nov 13 06:58:49 controller-1461 nova keystoneclient.middleware.auth_token DEBUG Marking token 211b590c4ba94d62a3981fbf91e934dc as unauthorized in memcache

Issue was fixed after the following was added to [keystone_authtoken] section in nova.conf to all controller's nodes:

token_cache_time=300 -> I think it may be skipped because it's default value
memcache_security_strategy=ENCRYPT
memcache_secret_key=hjhs445

memcache_secret_key is the same on all controllers.