nova-compute-drain.yml

---
- name: Drain a nova compute host of instances
  hosts: compute
  gather_facts: yes
  tags:
    - nova-compute-drain
  vars:
    venv: "{{ virtualenv_path }}/openstack"
    live_migration_fatal: true
  tasks:
    - name: Set up openstack cli virtualenv
      pip:
        virtualenv: "{{ venv }}"
        name:
          - python-openstackclient
        state: latest
        extra_args: "{% if pip_upper_constraints_file %}-c {{ pip_upper_constraints_file }}{% endif %}"
      run_once: true
      delegate_to: "{{ groups['controllers'][0] }}"

    - block:
        - name: Query instances
          command: >
            {{ venv }}/bin/openstack
            server list --host {{ ansible_facts.nodename }}
            --all-projects
            --status ACTIVE
            --format json
          register: instances

        - name: Live migrate instances
          command: >
            {{ venv }}/bin/openstack
            --os-compute-api-version 2.25
            server migrate
            {{ instance_uuid }}
            --live-migration
            --wait
          loop: "{{ instances.stdout | from_json }}"
          loop_control:
            label: "{{ instance_uuid }}"
          vars:
            instance_uuid: "{{ item.ID | default }}"
          register: result
          failed_when:
            - live_migration_fatal | bool
            - result is failed

        - name: Query instances
          command: >
            {{ venv }}/bin/openstack
            server list --host {{ ansible_facts.nodename }}
            --all-projects
            --status ACTIVE
            --format json
          register: instances

        - name: Fail if there are instances still on the host
          fail:
            msg: >
              Instances still on {{ inventory_hostname }}: {{ instances.stdout | from_json }}
          when:
            - live_migration_fatal | bool
            - instances.stdout | from_json | length > 0

      delegate_to: "{{ groups['controllers'][0] }}"
      environment: "{{ openstack_auth_env }}"
      when:
        - "'compute' in group_names"
        - groups['compute'] | length > 1
      vars:
        ansible_host: "{{ hostvars[groups['controllers'][0]].ansible_host }}"