OpenStack DevStack No such file or directory: '/etc/oslo/matchmaker_ring.json'

Context
========
Enabled "ZeroMQ"
http://fosshelp.blogspot.in/2014/05/how-to-openstack-devstack-setup-with.html
http://fosshelp.blogspot.com/2014/05/openstack-devstack-responseerror.html

1)
Getting error from following services
n-cond
n-crt
n-net
n-sch
n-cauth
h-eng

---- Error ----

2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup     _get_matchmaker().register(topic, CONF.rpc_zmq_host)
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup   File "/opt/stack/nova/nova/openstack/common/rpc/impl_zmq.py", line 817, in _get_matchmaker
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup     matchmaker = importutils.import_object(mm, *args, **kwargs)
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup   File "/opt/stack/nova/nova/openstack/common/importutils.py", line 40, in import_object
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup     return import_class(import_str)(*args, **kwargs)
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup   File "/opt/stack/nova/nova/openstack/common/rpc/matchmaker_ring.py", line 106, in __init__
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup     self.add_binding(mm.FanoutBinding(), FanoutRingExchange(ring))
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup   File "/opt/stack/nova/nova/openstack/common/rpc/matchmaker_ring.py", line 88, in __init__
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup     super(FanoutRingExchange, self).__init__(ring)
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup   File "/opt/stack/nova/nova/openstack/common/rpc/matchmaker_ring.py", line 57, in __init__
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup     fh = open(CONF.matchmaker_ring.ringfile, 'r')
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup IOError: [Errno 2] No such file or directory: '/etc/oslo/matchmaker_ring.json'
2014-05-30 18:59:11.648 TRACE nova.openstack.common.threadgroup

Fix
=====

Notes:
-----------
*
http://ewindisch.github.io/nova/ <=== IMP
The MatchMaker is pluggable and may also be used to enforce sending messages through a BROKER.
MatchMakerRing - loads a static hash table from a JSON file, cycles hosts per bare topic to create a directed topic.
The MatchMaker ring is a JSON file containing a hash where each key is a base topic and the values are arrays.
http://ewindisch.github.io/nova/#cmnt7 <=== IMP

a)
#sudo mkdir /etc/oslo
#sudo touch /etc/oslo/matchmaker_ring.json

b)
b1)
* Open /etc/oslo/matchmaker_ring.json and add following json string
    {
        "conductor":"conductor"
    }

b2)
Goto screen and check/restart "n-cond" services. Now "n-cond" service should start without any issue.

c)
Do the same for all other services where we getting this error of ZeroMQ

d)
Example of /etc/oslo/matchmaker_ring.json
    {
        "conductor":["controller","compute1","compute2","compute2"],
        "console":["controller","compute1","compute2","compute2"],
        "consoleauth":["controller","compute1","compute2","compute2"],
        "compute":["controller","compute1","compute2","compute2"],
        "cert":["controller","compute1","compute2","compute2"],
        "scheduler":["controller","compute1","compute2","compute3"],
        "metering": ["ceilometer1"],
        "notifications-info": ["ceilometer1"],
        "notifications-error": ["ceilometer1"]
    }