Tip

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3 - Basic

Run once

Cluster-specific operations must only be executed on ONE NODE AT A TIME!

Such operations include:

• Resource actions

• most Node actions

• Configuration changes

You can achieve this easily by either:

• use the ‘run_once: true’ parameter (dynamic)

  - hosts: linuxha
    gather_facts: false
    become: true
    tasks:
      - name: Run once per cluster
        ansibleguy.linuxha.raw:
          cmd: 'to execute'
        run_once: true
  

• add an inventory-group of ‘leader-nodes’ that will be used as execution targets (static but working for multi-cluster setup)

  inventory

  ---
  
  all:
    hosts:
      # cluster 1
      node1:
      node2:
      # cluster 2
      node3:
      node4:
    children:
      linuxha:
        hosts:
          node1:
          node2:
          node3:
          node4:
      linuxha_leader:
        hosts:
          node1:
          node3:
  

  playbook

  - hosts: linuxha_leader
    gather_facts: false
    become: true
    tasks:
      - name: Run once per cluster
        ansibleguy.linuxha.raw:
          cmd: 'to execute'