From 707398789403293aaedc1d78ddc4a164611366c7 Mon Sep 17 00:00:00 2001
From: Jimmy McCrory <jimmy.mccrory@gmail.com>
Date: Thu, 22 Feb 2018 08:55:06 -0800
Subject: [PATCH] Rearrange cell mapping tasks

Existing instances can be mapped to a newly created cell immediately
after the cell is created and by the same conductor host that created
the cell.

After a new compute host is built, it will need to mapped to a cell
through the 'discover_hosts' command of nova-manage. This command will
still need to be run against a host that has direct database access, but
the command is able to handle mapping of all compute hosts that do not
currently belong to the cell so it only needs to be run once per play.

There can be a short delay in the time between a compute service
starting and becoming available to be discovered and mapped but, for
most deployments, compute host discovery will be handled automatically
as a periodic task.

Conflicts:
>------tasks/main.yml

Change-Id: I4f7328e1aff79eb94f278999b97fbad8f44c6a3e
Closes-Bug: 1749037
Related-Bug: 1729661
Related-Bug: 1752540
(cherry picked from commit 6321cf90304023c20dc6abb87e2fa20107b7051d)
---
 tasks/main.yml               | 13 +++++--------
 tasks/nova_db_post_setup.yml | 20 ++------------------
 tasks/nova_db_setup.yml      | 15 +++++++++++++++
 3 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/tasks/main.yml b/tasks/main.yml
index 3b282c13..04e9f0e7 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -133,15 +133,12 @@
 # because the compute hosts do not have access to
 # the database connection string and therefore
 # cannot run nova-manage.
-# Also, we delegate this to a random host in the
-# conductor group in order to spread the load of
-# multiple forks across the group members.
 - include: nova_db_post_setup.yml
-  delegate_to: "{{ conductor_host }}"
-  with_random_choice: "{{ groups['nova_conductor'] }}"
-  loop_control:
-    loop_var: conductor_host
+  delegate_to: "{{ random_conductor }}"
+  run_once: true
   when:
-    - "'nova_compute' in group_names"
+    - "nova_services['nova-compute']['group'] in group_names"
+  vars:
+    random_conductor: "{{ groups[nova_services['nova-conductor']['group']] | random }}"
   tags:
     - nova-config
diff --git a/tasks/nova_db_post_setup.yml b/tasks/nova_db_post_setup.yml
index d6d4289c..758b4a4c 100644
--- a/tasks/nova_db_post_setup.yml
+++ b/tasks/nova_db_post_setup.yml
@@ -15,9 +15,8 @@
 
 - name: Set the delegated task facts
   set_fact:
-    _db_nova_bin: "{{ hostvars[conductor_host]['nova_bin'] | default(nova_bin) }}"
-    _db_nova_system_user_name: "{{ hostvars[conductor_host]['nova_system_user_name'] | default(nova_system_user_name) }}"
-    _db_nova_cell1_name: "{{ hostvars[conductor_host]['nova_cell1_name'] | default(nova_cell1_name) }}"
+    _db_nova_bin: "{{ hostvars[random_conductor]['nova_bin'] | default(nova_bin) }}"
+    _db_nova_system_user_name: "{{ hostvars[random_conductor]['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
@@ -25,18 +24,3 @@
   become: yes
   become_user: "{{ _db_nova_system_user_name }}"
   changed_when: false
-
-# When upgrading we need to map existing instances to the new cell1
-# To do this we need the cell UUID.
-- name: Get UUID of new Nova Cell
-  shell: "{{ _db_nova_bin }}/nova-manage cell_v2 list_cells | grep ' {{ _db_nova_cell1_name }} '"
-  become: yes
-  become_user: "{{ _db_nova_system_user_name }}"
-  register: cell1_uuid
-  changed_when: false
-
-- name: Map instances to new Cell1
-  command: "{{ _db_nova_bin }}/nova-manage cell_v2 map_instances --cell_uuid {{ cell1_uuid['stdout'].split()[3] }}"
-  become: yes
-  become_user: "{{ _db_nova_system_user_name }}"
-  changed_when: false
diff --git a/tasks/nova_db_setup.yml b/tasks/nova_db_setup.yml
index 5a342747..105345b9 100644
--- a/tasks/nova_db_setup.yml
+++ b/tasks/nova_db_setup.yml
@@ -73,3 +73,18 @@
   when:
     - not data_migrations | skipped
     - data_migrations | succeeded
+
+# When upgrading we need to map existing instances to the new cell1
+# To do this we need the cell UUID.
+- name: Get UUID of new Nova Cell
+  shell: "{{ nova_bin }}/nova-manage cell_v2 list_cells | grep ' {{ nova_cell1_name }} '"
+  become: yes
+  become_user: "{{ nova_system_user_name }}"
+  register: cell1_uuid
+  changed_when: false
+
+- name: Map instances to new Cell1
+  command: "{{ nova_bin }}/nova-manage cell_v2 map_instances --cell_uuid {{ cell1_uuid['stdout'].split()[3] }}"
+  become: yes
+  become_user: "{{ nova_system_user_name }}"
+  changed_when: false