From:
https://docs.hpcloud.com/commercial/GA1/1.1commerical.services-identity-configure-v3.html

To switch Horizon from Keystone v2 to Keystone v3:

  1. In each controller node, navigate to the local_settings.py file located in /opt/stack/venvs/openstack/lib/python2.7/site-packages/openstack_dashboard/local/local_settings.py

  2. Edit the file as follows:

a. Set the OpenStack API version to version 3:

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2
3
OPENSTACK_API_VERSIONS = {
"identity": 3,
}

b. Enable multi-domain support:

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OPENSTACK_KEYSTONE_MULTIDOMAIN_SUPPORT = True

c. Point to Keystone V3 endpoint:

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OPENSTACK_KEYSTONE_URL = "http://%s:5000/v3" % OPENSTACK_HOST

The Keystone v3 endpoint is in the format: http://:/v3 and is the same host/port as the v2 endpoint. The local_settings.py file will have the endpoint for v2 by default.

  1. Restart the apache server in each controller nodes:
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sudo service apache2 restart