OpenStack nova APi start error, could not bind to 0.0.0.0 address all ready in use

Openstack-nova-api doesn’t start, this error is  from the services boot priority in many times.

# service openstack-nova-api start

2015-03-03 15:05:06.402 3313 ERROR nova.wsgi [-] Could not bind to
0.0.0.0:8775
2015-03-03 15:05:06.402 3313 CRITICAL nova [-] error: [Errno 98] Address
already in use

# service openstack-nova-api status

openstack-nova-api dead but pid file exists*

This Error happens because openstack-nova-api and openstack-nova-metadata-api use the same ports.
You can start nova-api stopping metadata-api service and starting nova-api before, then start again metadata-api service.
# service openstack-nova-metadata-api stop
# service openstack-nova-api start
# service openstack-nova-metadata-api

This should fix your issue. After this you can set up boot order to this processes

# update-rc.d openstack-nova-api defaults <order>

Example: If openstack-nova-metadata-api got an order boot of S90openstack-nova-metadata-api, you should use update-rc to set nova-api start before nova-metadata-api

# update-rc.d openstack-nova-api defaults 90

This will set the priority of nova-api with the priority of nova-metadata-api, wich means that nova-api will run before metadata-api.