Ansible - 同一主机的多个/备用主机名

Question

假设我的主机具有多个 (DNS) 名称/IP，例如因为它们有多个 NIC，因此有到达它们的路由。

我想玩一本剧本，以防其中一条路线失败。由于我不知道哪一个有效，我想 ansible 尝试所有这些，然后只为该主机播放这本书一次。将所有主机的名称放入 list 并让它运行是很容易的，但是随后 playbook 将为每个主机名称执行一次。

问题:有没有办法指定备用主机名或告诉 ansible 仅在每个组的一台主机上运行 playbook？

Answer 1

可以实现

to run the playbook only on one host per group

请参阅下面的示例。

- hosts: jails-01                                                                            
  strategy: linear                                                                           
  vars:                                                                                      
    lock_file: /var/lock/my_ansible_hostname.lock                                                 
  tasks:                                                                                     
    - name: delete lock_file                                                                 
      file:                                                                                  
        path: "{{ lock_file }}"                                                              
        state: absent                                                                        
      run_once: true                                                                         
      delegate_to: localhost                                                                 
    - name: select host                                                                      
      shell: "echo {{ ansible_hostname }}  > {{ lock_file }}"                                
      args:                                                                                  
        creates: "{{ lock_file }}"                                                           
      delegate_to: localhost                                                                 
    - name: winner takes it all                                                              
      fail:                                                                                  
        msg: "Too late. Other thread is running. End of play."                               
      when: lookup('file', lock_file) != ansible_hostname                                    
    - name: go ahead                                                                         
      debug:                                                                                 
        msg: "{{ ansible_hostname }} goes ahead ... "


# ansible-playbook playbook.yml | grep msg
fatal: [test_01]: FAILED! => {"changed": false, "msg": "Too late. Other thread is running. End of play."}
fatal: [test_03]: FAILED! => {"changed": false, "msg": "Too late. Other thread is running. End of play."}
    "msg": "test_02 goes ahead ... "