allow/enable installation as alternate region

For those who want to deploy a new open-stack environment, it is easy - just use the ansible playbook and deploy it. \o/

I represent the use case of those who have a bit different requirement .. people who know and use the current ansible playbook to deploy new clusters, but are hired at companies that already have an existing openstack platfrom running ... and you have the task to carry it forward.

Due to various reasons - code changes, legacy, lack of documentation, hacked-to-death, you cannot upgrade the existing platform, and you do not want to "break" what is not broken -- take the risk of making changes to a running production platform

Installing a new platform means making a new business case, running two environments in parallel, and burden on the company for migration, new set of username and password , new billing <can insert a dozen more reasons here >

What would make our lives easier is the ability to deploy new clusters on an existing keystone .. so that the new deployment is registered as a new region. The only upgrade might be the keystone and register the new endpoints as region X.

This helps a lot because suddenly this opens up the possibility for anyone to just declare the old platform as EOL and have users move/migrate to the new platform. Since its multi region, you can also have one region on ubuntu and one on redhat/centos as well -- this opens up possibilities.

I cannot think of a way to get this started .. probably in the yaml file as

install_as_new_cluster = true
# install_as_new_cluster = false
# integrate_into_existing_keystone = true
# install_as_new_region_name = XXX
# keystone_db_user =
# keystone_db_pass =
# keystone_db_name =
# keystone_db_host =
# skip_horizon_install = true
# use_dedicated_horizon = true

## warning !! backup your keystone db as it might be upgraded to support the current release ##