Override hosts variable of Ansible playbook from the command line

Question

This is a fragment of a playbook that I\'m using (server.yml):

- name: Determine Remote User
  hosts: web
  gather_facts: false
  roles:
    - {         


        

Answer 1

I changed mine to default to no host and have a check to catch it. That way the user or cron is forced to provide a single host or group etc. I like the logic from the comment from @wallydrag. The empty_group contains no hosts in the inventory.

- hosts: "{{ variable_host | default('empty_group') }}"

Then add the check in tasks:

   tasks:
   - name: Fail script if required variable_host parameter is missing
     fail:
       msg: "You have to add the --extra-vars='variable_host='"
     when: (variable_host is not defined) or (variable_host == "")