Keystone cannot connect to mysql server in OpenStack

Issue

• Keystone is unable to start and shows the following in the logs:

ERROR keystone.common.wsgi [-] (OperationalError) (2003, "Can't connect to MySQL server on '10.10.73.6' (111)") None None
TRACE keystone.common.wsgi Traceback (most recent call last):
TRACE keystone.common.wsgi   File "/usr/lib/python2.6/site-packages/keystone/common/wsgi.py", line 238, in __call__
TRACE keystone.common.wsgi     result = method(context, **params)
TRACE keystone.common.wsgi   File "/usr/lib/python2.6/site-packages/keystone/token/controllers.py", line 94, in authenticate
TRACE keystone.common.wsgi     context, auth)
TRACE keystone.common.wsgi   File "/usr/lib/python2.6/site-packages/keystone/token/controllers.py", line 257, in _authenticate_local
TRACE keystone.common.wsgi     username, DEFAULT_DOMAIN_ID)
TRACE keystone.common.wsgi   File "/usr/lib/python2.6/site-packages/keystone/identity/core.py", line 177, in wrapper