Allow to switch from parallel to serial update.

We can encounter corner case pacemaker issues with parallel role
update. While we solve them, we need a way to disable parallel role
update.

Using a idiom mentionned in the ansible documentation[1] we start role
update by batch. When batch is 1, this is serial update, one role
after another.

This is the default.

[1] https://docs.ansible.com/ansible/latest/user_guide/playbooks_async.html

Change-Id: I03378557653d07113fa70782e5d22bf5e3e969b8
(cherry picked from commit 8d2027f1f1)
(cherry picked from commit a7704f6559)

defaults/main.yml

@@ -22,6 +22,7 @@ overcloud_upgrade: false
 undercloud_update: false
 overcloud_update: false
 overcloud_images_validate: false
+overcloud_batch_update: false
 
 # enable ffu upgrade
 ffu_undercloud_upgrade: false

tasks/update/overcloud_update_run.yml

@@ -2,26 +2,20 @@
 - name: import tasks from l3_agent_connectivity_check_start_script
   import_tasks: ../common/l3_agent_connectivity_check_start_script.yml
 
-- name: run overcloud minor update in each of the roles/hostgroups
-  async: 25200
-  poll: 0
-  shell: |
-        set -o pipefail
-        bash {{ overcloud_update_run_script_base }}-{{ item }}.sh 2>&1 {{ timestamper_cmd }} > \
-          {{ working_dir }}/overcloud_update_run_{{ item }}.log
-  loop: "{{ oc_roles|default(['all']) }}"
-  register: overcloud_update_nodes
-  ignore_errors: true
+- name: Are we running in parallel or serially ?
+  debug:
+    msg: "{{ (overcloud_batch_update|bool) | ternary('Running in parallel', 'Running serially') }}"
+
+- name: generate roles list from inventory file
+  import_tasks: ../common/load_roles_from_inventory.yaml
+  when: not oc_roles
+
+- name: Run update.
+  vars:
+    oc_current_role: "{{ item }}"
+  include_tasks: overcloud_update_run_role.yml
+  loop: "{{ oc_roles|default(['all'])|batch((overcloud_batch_update|bool) | ternary(100, 1))|list }}"
 
-- name: was the overcloud minor update successful?
-  async_status:
-    jid: "{{ async_result_item.ansible_job_id }}"
-  loop: "{{ overcloud_update_nodes.results }}"
-  loop_control:
-    loop_var: "async_result_item"
-  register: async_poll_results
-  until: async_poll_results.finished
-  retries: 25200
 
 - name: import tasks from l3_agent_connectivity_check_stop_script
   import_tasks: ../common/l3_agent_connectivity_check_stop_script.yml

tasks/update/overcloud_update_run_role.yml

@@ -0,0 +1,23 @@
+---
+- name: run overcloud minor update in each of the roles/hostgroups
+  async: 25200
+  poll: 0
+  shell: |
+        set -o pipefail
+        bash {{ overcloud_update_run_script_base }}-{{ oc_running_role }}.sh 2>&1 {{ timestamper_cmd }} > \
+          {{ working_dir }}/overcloud_update_run_{{ oc_running_role }}.log
+  loop: "{{ oc_current_role }}"
+  loop_control:
+    loop_var: "oc_running_role"
+  register: overcloud_update_nodes
+  ignore_errors: true
+
+- name: was the overcloud minor update successful?
+  async_status:
+    jid: "{{ async_result_item.ansible_job_id }}"
+  loop: "{{ overcloud_update_nodes.results }}"
+  loop_control:
+    loop_var: "async_result_item"
+  register: async_poll_results
+  until: async_poll_results.finished
+  retries: 25200