title: Ansible playbook doesn't pickup host variables
body: <p>I am trying to run a playbook which execute against variables stored in the host_vars. This is the solution layout:</p>
  
  <ul>
  <li><strong><em>/host_vars/f5-test</em></strong></li>
  <li><strong><em>/inventory/hosts</em></strong></li>
  <li><strong><em>/playbook.yml</em></strong></li>
  </ul>
  
  <p>The content of the files are as follows:</p>
  
  <p><strong>/inventory/host:</strong></p>
  
  <pre><code>[f5-test]
  localhost
  </code></pre>
  
  <p><strong>/host_vars/hosts</strong></p>
  
  <pre><code>f5_user:user
  f5_password:password
  f5_server:server
  </code></pre>
  
  <p><strong>/playbook.yml</strong></p>
  
  <pre><code>- name: Playbook
    hosts: f5-test
    gather_facts: no
    gather_subset: no
  
    tasks:
      - name: Taks_01
        tags: "bigip-node"
        bigip_node:
          server: "{{f5_server}}"
          user: "{{f5_user}}"
          password: "{{f5_password}}"
          state: "present"
          partition: "Common"
          host: "10.20.30.40"
          name: "F5_Node"
          session_state: "enabled"
          description: "description"
        delegate_to: localhost
  </code></pre>
  
  <p>However when we execute the following command:</p>
  
  <p><strong><em>sudo ansible-playbook playbook.yml -i inventory/hosts -vvvv</em></strong></p>
  
  <p>I get the following error:</p>
  
  <pre><code>task path: /home/dev/ansible/playbook.yml:9
  fatal: [localhost]: FAILED! =&gt; {
      "failed": true,
      "msg": "the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: 'f5_server' is undefined\n\nThe error appears to have been in '/home/dev/ansible/playbook.yml': line 9, column 7, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n  tasks:\n    - name: Task_01\n      ^ here\n"
  }
  </code></pre>
  
  <p>Any idea why it is not being picked up? I set up my project in the same structure found in the F5 ansible example, which can be found <a href="https://github.com/F5Networks/f5-ansible/tree/devel/examples" rel="nofollow noreferrer">here</a>.</p>
  
  <p>Thanks!</p>