ANSIBLE: RUN PLAY ONLY ON REACHABLE HOST

During one of my Ansible trainings in Singapore one candidate asked me, is there some way that we execute the play only on reachable hosts. She also insisted that the playbook should show no errors. Showing errors would report the Job as failed in Ansible Tower. So, finally we came out with a solution and it worked really well.

Our First play would be to check reachable hosts, and create a new group of the reachable hosts.

- name: check reachable hosts
  hosts: all
  gather_facts: no
  tasks:
    - command: ping -c1 {{ inventory_hostname }}
      delegate_to: localhost
      register: ping_result
      ignore_errors: yes
    - group_by: key=reachable
      when: ping_result|success

• We use command module to ping a host and delegate the task to localhost
• using group_by module, if the host is reachable we add it to a new group called reachable

Next play would be the one that you want to run only on reachable hosts.

- name: your actual play
  hosts: reachable
  gather_facts: yes
  tasks:
    - debug: msg="this is {{ ansible_hostname }}"

happy ;)

This playbook is also available on GitHub

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