title: Ansible: want to apply variables to a group of inventories
body: <p>I have some inventories defined, containing software version numbers defined in variables.</p>
  
  <p>I'd like to share the same version numbers between my prod and UAT inventories in order to guarantee that a prod release matches what was tested in UAT.</p>
  
  <p>Is is possible to share variables between some inventories and not others (I suppose this might mean conceptually "grouping" inventories)?</p>
  
  <p>Example of my current setup</p>
  
  <p>Content of <code>/prod/group_vars/all</code>:</p>
  
  <blockquote>
  <pre><code>   my-app-verion: 1.0.0
  </code></pre>
  </blockquote>
  
  <p>Content of <code>/uat/group_vars/all</code>:</p>
  
  <blockquote>
  <pre><code>   my-app-verion: 1.0.0
  </code></pre>
  </blockquote>
  
  <p>Content of <code>/dev/group_vars/all</code>:</p>
  
  <blockquote>
  <pre><code>   my-app-verion: LATEST
  </code></pre>
  </blockquote>
  
  <p>I would like to have one file that's shared by the <code>prod</code> and <code>uat</code> inventories and contains</p>
  
  <blockquote>
  <pre><code>    my-app-verion: 1.0.0
  </code></pre>
  </blockquote>