.. _multi-regions:

======================================
Multiple Regions Deployment with Kolla
======================================

This section describes how to perform a basic multiple regions deployment
with Kolla. A basic multiple regions deployment consists of separate
OpenStack installation in two or more regions (RegionOne, RegionTwo, ...)
with a shared Keystone and Horizon. The rest of this documentation assumes
Keystone and Horizon are deployed in RegionOne, and other regions have
access to the admin endpoint (i.e., ``kolla_internal_fqdn``) of RegionOne.
It also assumes that the operator knows the name of all OpenStack regions
in advance, and considers as many Kolla deployments as there are regions.

There are specifications of multiple regions deployment at:
`<http://docs.openstack.org/arch-design/multi-site-architecture.html>`__
and
`<https://wiki.openstack.org/wiki/Heat/Blueprints/Multi_Region_Support_for_Heat>`__.

Deployment of the first region with Keystone and Horizon
========================================================

Deployment of the first region results in a typical Kolla deployment
whenever, it is an *all-in-one* or *multinode* deployment (see
:doc:`quickstart`). It only requires slight modifications in the
``/etc/kolla/globals.yml`` configuration file. First of all, ensure that
Keystone and Horizon are enabled:

::

   enable_keystone: "yes"
   enable_horizon: "yes"

Then, change the value of ``multiple_regions_names`` to add names of other
regions. In this example, we consider two regions. The current one,
formerly knows as RegionOne, that is hided behind
``openstack_region_name`` variable, and the RegionTwo:

::

   openstack_region_name: "RegionOne"
   multiple_regions_names:
       - "{{ openstack_region_name }}"
       - "RegionTwo"

.. note:: Kolla uses these variables to create necessary endpoints into
          Keystone so that services of other regions can access it. Kolla
          also updates the Horizon ``local_settings`` to support multiple
          regions.

Finally, note the value of ``kolla_internal_fqdn`` and run
``kolla-ansible``. The ``kolla_internal_fqdn`` value will be used by other
regions to contact Keystone. For the sake of this example, we assume the
value of ``kolla_internal_fqdn`` is ``10.10.10.254``.

Deployment of other regions
===========================

Deployment of other regions follows an usual Kolla deployment except that
OpenStack services connect to the RegionOne's Keystone. This implies to
update the ``/etc/kolla/globals.yml`` configuration file to tell Kolla how
to reach Keystone. In the following, ``kolla_internal_fqdn_r1`` refers to
the value of ``kolla_internal_fqdn`` in RegionOne:

::

   kolla_internal_fqdn_r1: 10.10.10.254

   keystone_admin_url: "{{ admin_protocol }}://{{ kolla_internal_fqdn_r1 }}:{{ keystone_admin_port }}/v3"
   keystone_internal_url: "{{ internal_protocol }}://{{ kolla_internal_fqdn_r1 }}:{{ keystone_public_port }}/v3"

   openstack_auth:
       auth_url: "{{ admin_protocol }}://{{ kolla_internal_fqdn_r1 }}:{{ keystone_admin_port }}"
       username: "admin"
       password: "{{ keystone_admin_password }}"
       project_name: "admin"

Configuration files of nova/neutron/glance... have to be updated to
contact RegionOne's Keystone. Fortunately, Kolla offers to override all
configuration files at the same time thanks to the
``node_custom_config`` variable (see :ref:`service-config`). This
implies to create a ``global.conf`` file with the following content:

::

   [keystone_authtoken]
   auth_uri = {{ keystone_internal_url }}
   auth_url = {{ keystone_admin_url }}

The Placement API section inside the nova configuration file also has
to be updated to contact RegionOne's Keystone. So create, in the same
directory, a ``nova.conf`` file with below content:

::

   [placement]
   auth_url = {{ keystone_admin_url }}

And link the directory that contains these files into the
``/etc/kolla/globals.yml``:

::

   node_custom_config: path/to/the/directory/of/global&nova_conf/

Also, change the name of the current region. For instance, RegionTwo:

::

   openstack_region_name: "RegionTwo"

Finally, disable the deployment of Keystone and Horizon that are
unnecessary in this region and run ``kolla-ansible``:

::

   enable_keystone: "no"
   enable_horizon: "no"

The configuration is the same for any other region.