Configure DB addresses for each service

To enable partitioning of DB traffic by-service, each service needs to
use a custom connection string. Defaulting the service address to a
common galera_address makes things continue to work by default.

While the galera_address could be overridden on a container or host
basis this requires repeating that behavior across each infra node in
the inventory. Providing service-specific connection address variables
simplifies the management somewhat for large deployments and may reduce
error rates.

The service install playbooks now default the service-specific variables
instead of galera_address to the internal lb vip from inventory to
maintain the ease-of-use currently available.

Any value for a service-specific variable set in user_variables.yml will
override the value in the playbook's vars to provide selective
customization as needed.

Change-Id: I4c98bf906a0c1cb11ddd41277a855dce22ff646a
Closes-Bug: 1462529

README.rst

@@ -24,4 +24,4 @@ This role will install the following:
       roles:
         - { role: "os_nova", tags: [ "os-nova" ] }
       vars:
-        galera_address: "{{ internal_lb_vip_address }}"
+        nova_galera_address: "{{ internal_lb_vip_address }}"

tasks/nova_db_setup.yml

@@ -17,7 +17,7 @@
   mysql_db:
     login_user: "{{ galera_root_user }}"
     login_password: "{{ galera_root_password }}"
-    login_host: "{{ galera_address }}"
+    login_host: "{{ nova_galera_address }}"
     name: "{{ nova_galera_database }}"
     state: "present"
   tags:
@@ -27,7 +27,7 @@
   mysql_user:
     login_user: "{{ galera_root_user }}"
     login_password: "{{ galera_root_password }}"
-    login_host: "{{ galera_address }}"
+    login_host: "{{ nova_galera_address }}"
     name: "{{ nova_galera_user }}"
     password: "{{ nova_container_mysql_password }}"
     host: "{{ item }}"

templates/nova.conf.j2

@@ -176,7 +176,7 @@ check_revocations_for_cached = False
 
 {% if inventory_hostname not in groups['nova_compute'] %}
 [database]
-connection = mysql://{{ nova_galera_user }}:{{ nova_container_mysql_password }}@{{ galera_address }}/{{ nova_galera_database }}?charset=utf8
+connection = mysql://{{ nova_galera_user }}:{{ nova_container_mysql_password }}@{{ nova_galera_address }}/{{ nova_galera_database }}?charset=utf8
 max_overflow = {{ nova_db_max_overflow }}
 max_pool_size = {{ nova_db_max_pool_size }}
 pool_timeout = {{ nova_db_pool_timeout }}