AnsibleByExample

Execute command on the Ansible host — Ansible localhost

Beginneransiblelocalhosttaskplugin
2024-01-012By Luca Berton

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  18. 18. Testing and Linting (Quality Gates)
  19. 19. Advanced Debugging Playbook Failures
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How to Execute command on the Ansible host?

When Ansible becomes part of your daily workflow it is natural you would like to automate also task in your local machine.

Execute command on the Ansible host options

  • connection plugin
  • delegate_to: localhost
  • local_action

There are three ways to execute modules and commands on the Ansible Controller host. The first and my favorite is using the connection plugin local and applying it to the Ansible Play level of your Playbook. The tricky was is to adjust some ansible variables about the python interpreter. I consider it the best way nowadays. The second way is using the delegate_to at the Task level. This has the advantage to delegate only one task to localhost but still needs only the implicit localhost scheme. The third way is using the local_action statement. I personally don't like it but it's one alternative as well at Task level, so same as the previous.

Playbook

How to Execute command on the Ansible host using connection: local method.

code

---
- name: localhost Playbook
  hosts: localhost
  vars:
    ansible_connection: local
    ansible_python_interpreter: "{{ ansible_playbook_python }}"
  tasks:
    - name: print hostname
      ansible.builtin.debug:
        msg: "{{ inventory_hostname }}"

execution

ansible-pilot $ ansible-playbook ansible\ statements/localhost.yml
[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit
localhost does not match 'all'
PLAY [localhost Playbook] *****************************************************************************
TASK [Gathering Facts] ****************************************************************************
ok: [localhost]
TASK [print hostname] *****************************************************************************
ok: [localhost] => {
    "msg": "localhost"
}
PLAY RECAP ****************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
ansible-pilot $

idempotency

ansible-pilot $ ansible-playbook ansible\ statements/localhost.yml
[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit
localhost does not match 'all'
PLAY [localhost Playbook] *****************************************************************************
TASK [Gathering Facts] ****************************************************************************
ok: [localhost]
TASK [print hostname] *****************************************************************************
ok: [localhost] => {
    "msg": "localhost"
}
PLAY RECAP ****************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
ansible-pilot $

Conclusion

Now you know how to Execute commands and tasks on the Ansible localhost. You know how to use it based on your use case.

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