browbeat/ansible/browbeat/adjustment-nova-scheduler.yml

---
#
# Playbook to adjust Nova Scheduler settings to avoid over-scheduling hosts
# with greater memory in uneven memory environments.
#
# Versions tested: Newton, Ocata, Pike
#
# Examples:
# ansible-playbook -i hosts browbeat/adjustment-nova-scheduler.yml -e 'max_instances_per_host=350'
# ansible-playbook -i hosts browbeat/adjustment-nova-scheduler.yml -e 'max_instances_per_host=350 ram_weight_multiplier=0'
# ansible-playbook -i hosts browbeat/adjustment-nova-scheduler.yml -e 'max_instances_per_host=350 ram_weight_multiplier=0 enabled_filters="NumInstancesFilter,RetryFilter,ComputeFilter"'
# ansible-playbook -i hosts browbeat/adjustment-nova-scheduler.yml -e 'max_instances_per_host=350 ram_weight_multiplier=0 enabled_filters="NumInstancesFilter,RetryFilter,ComputeFilter" host_subset_size=4'
#
# In order for new settings to take affect, you need to restart the Nova services
# by adding variable restart_nova=true into the extra vars.
#
# ansible-playbook -i hosts browbeat/adjustment-nova-scheduler.yml -e 'max_instances_per_host=350 ram_weight_multiplier=0 enabled_filters="NumInstancesFilter,RetryFilter,ComputeFilter" host_subset_size=4 restart_nova=true'
#
# * Note not setting a variable does not change that configuration item then. Setting no variables
#   and running the playbook sets all configuration items to defaults (Ocata)
#
# ansible-playbook -i hosts browbeat/adjustment-nova-scheduler.yml
#

- hosts: controller
  remote_user: "{{ host_remote_user }}"
  gather_facts: false
  vars_files:
    - ../install/group_vars/all.yml
  vars:
    restart_nova: false
    # Create initial blank configuration list
    nova_configuration: []
    # Defaults
    default_max_instances_per_host: 50
    default_ram_weight_multiplier: 1.0
    default_enabled_filters: "RetryFilter,AvailabilityZoneFilter,ComputeFilter,ComputeCapabilitiesFilter,ImagePropertiesFilter,ServerGroupAntiAffinityFilter,ServerGroupAffinityFilter"
    default_host_subset_size: 1
    # Each configuration item needs to be a list so it can be merged
    max_instances_per_host_item: []
    ram_weight_multiplier_item: []
    enabled_filters_item: []
    host_subset_size_item: []

  pre_tasks:
    - name: Get OSP Version
      slurp:
        src: "/etc/rhosp-release"
      register: osp_version
      become: true

    - name: (Newton, Ocata) Set Config File based on OpenStack Version
      set_fact:
        nova_config_file: /etc/nova/nova.conf
      when: "('Newton' in osp_version['content'] | b64decode or 'Ocata' in osp_version['content'] | b64decode)"

    - name: (Pike) Set Config File based on OpenStack Version
      set_fact:
        nova_config_file: /var/lib/config-data/puppet-generated/nova/etc/nova/nova.conf
      when: "'Pike' in osp_version['content'] | b64decode"

    - name: Set default max_instances_per_host, ram_weight_multiplier, enabled_filters, and host_subset_size
      set_fact:
        nova_configuration:
          - section: filter_scheduler
            option: max_instances_per_host
            value: "{{default_max_instances_per_host}}"
          - section: filter_scheduler
            option: ram_weight_multiplier
            value: "{{default_ram_weight_multiplier}}"
          - section: filter_scheduler
            option: enabled_filters
            value: "{{default_enabled_filters}}"
          - section: filter_scheduler
            option: host_subset_size
            value: "{{default_host_subset_size}}"
      when: max_instances_per_host is undefined and ram_weight_multiplier is undefined and enabled_filters is undefined and host_subset_size is undefined

    - name: Set max_instances_per_host configuration for Nova
      set_fact:
        max_instances_per_host_item:
          - section: filter_scheduler
            option: max_instances_per_host
            value: "{{max_instances_per_host}}"
      when: max_instances_per_host is defined

    - name: Set ram_weight_multiplier configuration for Nova
      set_fact:
        ram_weight_multiplier_item:
          - section: filter_scheduler
            option: ram_weight_multiplier
            value: "{{ram_weight_multiplier}}"
      when: ram_weight_multiplier is defined

    - name: Set enabled_filters configuration for Nova
      set_fact:
        enabled_filters_item:
          - section: filter_scheduler
            option: enabled_filters
            value: "{{enabled_filters}}"
      when: enabled_filters is defined

    - name: Set host_subset_size configuration for Nova
      set_fact:
        host_subset_size_item:
          - section: filter_scheduler
            option: host_subset_size
            value: "{{host_subset_size}}"
      when: host_subset_size is defined

    - name: Merge configuration items
      set_fact:
        nova_configuration: "{{nova_configuration + max_instances_per_host_item + ram_weight_multiplier_item + enabled_filters_item + host_subset_size_item }}"

  roles:
    - nova-config

  post_tasks:
    - name: (Newton, Ocata) Restart Nova Services
      become: true
      service:
        name: "{{ item }}"
        state: restarted
      with_items:
        - openstack-nova-scheduler
        - openstack-nova-api
        - openstack-nova-conductor
        - openstack-nova-novncproxy
        - openstack-nova-consoleauth
        - httpd
      when: "('Newton' in osp_version['content'] | b64decode or 'Ocata' in osp_version['content'] | b64decode) and (restart_nova)"

    - name: (Pike) Restart Nova Scheduler Container
      become: true
      command: "docker restart {{item}}"
      with_items:
        - nova_scheduler
      when: "('Pike' in osp_version['content'] | b64decode) and (restart_nova)"