setup: allow custom conductor host

This patch allows using a custom conductor host to do all the
deployment and setup steps when installing a brand new compute
node such as adding cell mappings, etc.

Change-Id: I61fc92d17d32e367ac133000d06bc83358735312

defaults/main.yml

@@ -32,6 +32,10 @@ debug: False
 nova_service_setup_host: "{{ openstack_service_setup_host | default('localhost') }}"
 nova_service_setup_host_python_interpreter: "{{ openstack_service_setup_host_python_interpreter | default((nova_service_setup_host == 'localhost') | ternary(ansible_playbook_python, ansible_python['executable'])) }}"
 
+# Set the host which will run compute initialization tasks such as checking
+# for a compute node to be up and running cell discovery.
+nova_conductor_setup_host: "{{ groups[nova_services['nova-conductor']['group']][0] }}"
+
 # Set the package install state for distribution and pip packages
 # Options are 'present' and 'latest'
 nova_package_state: "latest"

tasks/main.yml

@@ -197,12 +197,11 @@
 # where we want to isolate the clouds.yaml configuration,
 # rather than have it implemented on all compute nodes.
 - import_tasks: nova_compute_wait.yml
-  delegate_to: "{{ first_conductor }}"
+  delegate_to: "{{ nova_conductor_setup_host }}"
   when:
     - "nova_services['nova-compute']['group'] in group_names"
     - "nova_discover_hosts_in_cells_interval | int < 1"
   vars:
-    first_conductor: "{{ groups[nova_services['nova-conductor']['group']][0] }}"
     compute_host_to_wait_for: "{{ ansible_nodename }}"
   tags:
     - nova-config
@@ -212,11 +211,9 @@
 # the database connection string and therefore
 # cannot run nova-manage.
 - import_tasks: nova_db_post_setup.yml
-  delegate_to: "{{ first_conductor }}"
+  delegate_to: "{{ nova_conductor_setup_host }}"
   run_once: true
   when:
     - "nova_services['nova-compute']['group'] in group_names"
-  vars:
-    first_conductor: "{{ groups[nova_services['nova-conductor']['group']][0] }}"
   tags:
     - nova-config

tasks/nova_compute_wait.yml

@@ -19,7 +19,7 @@
 
 - name: Set the delegated task facts
   set_fact:
-    _wait_nova_bin: "{{ hostvars[first_conductor]['nova_bin'] | default(nova_bin) }}"
+    _wait_nova_bin: "{{ hostvars[nova_conductor_setup_host]['nova_bin'] | default(nova_bin) }}"
 
 - block:
     - name: Wait for the nova-compute service to initialize

tasks/nova_db_post_setup.yml

@@ -15,8 +15,8 @@
 
 - name: Set the delegated task facts
   set_fact:
-    _db_nova_bin: "{{ hostvars[first_conductor]['nova_bin'] | default(nova_bin) }}"
-    _db_nova_system_user_name: "{{ hostvars[first_conductor]['nova_system_user_name'] | default(nova_system_user_name) }}"
+    _db_nova_bin: "{{ hostvars[nova_conductor_setup_host]['nova_bin'] | default(nova_bin) }}"
+    _db_nova_system_user_name: "{{ hostvars[nova_conductor_setup_host]['nova_system_user_name'] | default(nova_system_user_name) }}"
 
 # This needs to be done after Compute hosts are added.
 - name: Perform a cell_v2 discover