Add set-src-dest-host role

The role will find out the available hosts and set
compute.migration_source_host and compute.migration_dest_host
options in tempest.conf if tempest_set_src_dest_host is set to
True.

Change-Id: Ic01970b100a7bb30d9c78229204c7de67681108c

playbooks/devstack-tempest.yaml

@@ -20,6 +20,11 @@
       include_role:
         name: acl-devstack-files
 
+    - name: Set source and destination host
+      include_role:
+        name: set-src-dest-host
+      when: tempest_set_src_dest_host is defined and tempest_set_src_dest_host | bool
+
     - name: Run tempest cleanup init-saved-state
       include_role:
         name: tempest-cleanup

roles/set-src-dest-host/defaults/main.yaml

@@ -0,0 +1 @@
+devstack_base_dir: /opt/stack

roles/set-src-dest-host/tasks/main.yaml

@@ -0,0 +1,29 @@
+- name: Find out hostnames
+  set_fact:
+      devstack_hostnames: "{{ devstack_hostnames|default([]) + [hostvars[zj_item]['ansible_hostname'] | default('unknown')] }}"
+  loop: "{{ query('inventory_hostnames', 'all,!localhost') }}"
+  loop_control:
+    loop_var: zj_item
+  ignore_errors: yes  # noqa ignore-errors
+
+- name: Found hostnames
+  debug:
+    msg: |
+      # Available hosts
+      {{ devstack_hostnames }}
+
+- name: Set migration_source_host in tempest.conf
+  become: true
+  community.general.ini_file:
+    path: "{{ devstack_base_dir }}/tempest/etc/tempest.conf"
+    section: compute
+    option: migration_source_host
+    value: "{{ devstack_hostnames[0] }}"
+
+- name: Set migration_dest_host in tempest.conf
+  become: true
+  community.general.ini_file:
+    path: "{{ devstack_base_dir }}/tempest/etc/tempest.conf"
+    section: compute
+    option: migration_dest_host
+    value: "{{ devstack_hostnames[1] }}"

zuul.d/integrated-gate.yaml

@@ -263,6 +263,7 @@
       # requests to services and can cause more oom issues. To avoid the
       # oom issue, setting the concurrency to 4 in this job.
       tempest_concurrency: 4
+      tempest_set_src_dest_host: true
       devstack_localrc:
         USE_PYTHON3: true
       devstack_plugins: