Pacemaker role for Ansible

This role configures Pacemaker cluster by dumping the configuration (CIB), adjusting the XML, and reloading it. The role is idempotent, and supports check mode.

It has been redesigned to configure individual elements (cluster defaults, resources, groups, constraints, etc) rather than the whole state of the cluster and all the services. This allows you to focus on specific resources, without interfering with the rest.

Requirements

This role has been written for and tested in Scientific Linux 7. It might also work in other distros, please share your experience.

Tasks

Use tasks_from Ansible directive to specify what you want to configure.

Boolean values in properties (parsed by Pacemaker itself) don't have to be quoted. However, resource agents may expect Boolean-like arguments as integers, strings, etc. Such values must be quoted.

tasks_from: main

Set up nodes, configure cluster properties, and resource defaults.

pcmk_cluster_name

Name of the cluster (optional).

Default: hacluster.

pcmk_password

The plaintext password for the cluster user (optional). If omitted, will be derived from ansible_machine_id of the first host in the play batch. This password is only used in the initial authentication of the nodes.

Default: ansible_machine_id | to_uuid

pcmk_user

The system user to authenticate PCS nodes with (optional). PCS will authenticate all nodes with each other.

Default: hacluster

pcmk_cluster_options

Dictionary with cluster-wide options (optional).

pcmk_votequorum

Dictionary with votequorum options (optional). See votequorum(5). Boolean values accepted.

pcmk_resource_defaults

Dictionary of resource defaults (optional).

tasks_from: resource

Configure a simple resource.

pcmk_resource

Dictionary describing a simple (primitive) resource. Contains the following members:

• id: resource identifier; mandatory for simple resources;
• class, provider, and type: resource agent descriptors; provider may be omitted, e.g. when type is service;
• options: optional dictionary of resource-specific attributes, e.g. address and netmask for IPaddr2;
• op: optional list of operations; each operation is a dictionary with required name and interval members, and optional arbitrary members;
• meta: optional dictionary of meta-attributes.

tasks_from: group

Configure a resource group.

pcmk_group

Dictionary with two members:

• id is the group identifier
• resources is a dictionary where keys are resource IDs, and values have the same format as pcmk_resource (except for id of the resources being optional).

tasks_from: constraint

Configure a constraint.

pcmk_constraint

Dictionary defining a single constraint. The following members are required:

• type: one of: location, colocation, or order;
• score: constraint score (signed integer, INFINITY, or -INFINITY).

Depending on the value of type, the following members are also required:

• location requires rsc and node;
• colocation requires rsc and with-rsc;
• order requires first and then;

The dictionary may contain other members, e.g. symmetrical.

Example playbooks

Active-active chrooted BIND DNS server

---
- name: Configure DNS cluster
  hosts: dns-servers
  tasks:

    - name: Set up cluster
      include_role:
        name: devgateway.pacemaker
      vars:
        pcmk_password: hunter2
        pcmk_cluster_name: named
        pcmk_cluster_options:
          stonith-enabled: false

    - name: Configure IP address resource
      include_role:
        name: devgateway.pacemaker
        tasks_from: resource
      vars:
        pcmk_resource:
          id: dns-ip
          class: ocf
          provider: heartbeat
          type: IPaddr2
          options:
            ip: 10.0.0.1
            cidr_netmask: 8
          op:
            - name: monitor
              interval: 5s

    - name: Configure cloned BIND resource
      include_role:
        name: devgateway.pacemaker
        tasks_from: advanced-resource
      vars:
        pcmk_resource:
          type: clone
          id: dns-clone
          resources:
            named:
              class: service
              type: named-chroot
              op:
                - name: monitor
                  interval: 5s

    - name: Set up constraints
      include_role:
        name: devgateway.pacemaker
        tasks_from: constraint
      vars:
        pcmk_constraint:
          type: order
          first: dns-ip
          then: dns-clone

Active-active Squid proxy

---
- name: Configure Squid cluster
  hosts: proxy-servers
  tasks:

    - name: Set up cluster
      include_role:
        name: devgateway.pacemaker
      vars:
        pcmk_password: hunter2
        pcmk_cluster_name: squid
        pcmk_cluster_options:
          stonith-enabled: false

    - name: Configure IP address resource
      include_role:
        name: devgateway.pacemaker
        tasks_from: resource
      vars:
        pcmk_resource:
          id: squid-ip
          class: ocf
          provider: heartbeat
          type: IPaddr2
          options:
            ip: 192.168.0.200
            cidr_netmask: 24
          op:
            - name: monitor
              interval: 5s

    - name: Configure cloned BIND resource
      include_role:
        name: devgateway.pacemaker
        tasks_from: advanced-resource
      vars:
        pcmk_resource:
          id: squid
            type: clone
            resources:
              squid-service:
                class: service
                type: squid
                op:
                  - name: monitor
                    interval: 5s

    - name: Set up constraints
      include_role:
        name: devgateway.pacemaker
        tasks_from: constraint
      vars:
        pcmk_constraint:
          type: order
          first: squid-ip
          then: squid

Nginx, web application, and master-slave Postgres

The cluster runs two Postgres nodes with synchronous replication. Wherever master is, a virtual IP address is running, where NAT is pointing at. Nginx and the webapp are running at the same node, but not the other, in order to save resources. Based on the example from Clusterlabs wiki.

---
- hosts:
    - alpha
    - bravo
  tasks:

    - name: Set up Pacemaker with Postgres master/slave
      include_role:
        name: devgateway.pacemaker
      vars:
        pcmk_pretty_xml: true
        pcmk_cluster_name: example
        pcmk_password: hunter2
        pcmk_cluster_options:
          no-quorum-policy: ignore
          stonith-enabled: false
        pcmk_resource_defaults:
          resource-stickiness: INFINITY
          migration-threshold: 1

    - name: Configure simple resources
      include_role:
        name: devgateway.pacemaker
        tasks_from: resource
      loop_control:
        loop_var: pcmk_resource
      loop:
        - id: coolapp
          class: service
          type: coolapp
        - id: nginx
          class: service
          type: nginx
        - id: virtual-ip
          class: ocf
          provider: heartbeat
          type: IPaddr2
          options:
            ip: 10.0.0.23
          meta:
            migration-threshold: 0
          op:
            - name: start
              timeout: 60s
              interval: 0s
              on-fail: restart
            - name: monitor
              timeout: 60s
              interval: 10s
              on-fail: restart
            - name: stop
              timeout: 60s
              interval: 0s
              on-fail: restart

    - name: Configure master-slave Postgres
      include_role:
        name: devgateway.pacemaker
        tasks_from: advanced-resource
      vars:
        pcmk_resource:
          id: postgres
          type: master
          meta:
            master-max: 1
            master-node-max: 1
            clone-max: 2
            clone-node-max: 1
            notify: true
          resources:
            postgres-replica-set:
              class: ocf
              provider: heartbeat
              type: pgsql
              options:
                pgctl: /usr/pgsql-9.4/bin/pg_ctl
                psql: /usr/pgsql-9.4/bin/psql
                pgdata: /var/lib/pgsql/9.4/data
                rep_mode: sync
                node_list: "{{ ansible_play_batch | join(' ') }}"
                restore_command: cp /var/lib/pgsql/9.4/archive/%f %p
                master_ip: 10.0.0.23
                restart_on_promote: "true"
                repuser: replication
              op:
                - name: start
                  timeout: 60s
                  interval: 0s
                  on-fail: restart
                - name: monitor
                  timeout: 60s
                  interval: 4s
                  on-fail: restart
                - name: monitor
                  timeout: 60s
                  interval: 3s
                  on-fail: restart
                  role: Master
                - name: promote
                  timeout: 60s
                  interval: 0s
                  on-fail: restart
                - name: demote
                  timeout: 60s
                  interval: 0s
                  on-fail: stop
                - name: stop
                  timeout: 60s
                  interval: 0s
                  on-fail: block
                - name: notify
                  timeout: 60s
                  interval: 0s

    - name: Set up constraints
      include_role:
        name: devgateway.pacemaker
        tasks_from: constraint
      loop_control:
        loop_var: pcmk_constraint
      loop:
        - type: colocation
          rsc: virtual-ip
          with-rsc: postgres
          with-rsc-role: Master
          score: INFINITY
        - type: colocation
          rsc: nginx
          with-rsc: virtual-ip
          score: INFINITY
        - type: colocation
          rsc: coolapp
          with-rsc: virtual-ip
          score: INFINITY
        - type: order
          first: postgres
          first-action: promote
          then: virtual-ip
          then-action: start
          symmetrical: false
          score: INFINITY
        - type: order
          first: postgres
          first-action: demote
          then: virtual-ip
          then-action: stop
          symmetrical: false
          score: 0

See also

• The official Pacemaker documentation

Copyright

Copyright 2015-2019, Development Gateway. Licensed under GPL v3+.