title: Can I set remote_user in host_vars or group_vars?
body: <p>I'm starting to write my first serious playbook in ansible.</p>
  
  <p>Something I'd like to do is to specify different <code>remote_user</code> values per host. I'm able to set <code>remote_user</code> in ansible.cfg, through the CLI <code>-u</code> option and even in play variables, like so:</p>
  
  <pre><code>---
  - name: install dependencies
    hosts: all
    sudo: yes
    vars:
      remote_user: username
  </code></pre>
  
  <p>But setting the var at the host or group level (which makes the most sense for my approach) won't work. For instance, having this file as <code>group_vars/all</code> gets me an "Authentication failure" fatal error:</p>
  
  <pre><code>---
  remote_user: username
  </code></pre>
  
  <p>What am I missing?</p>