title: Kubernetes: extract environment variables from a file when pod kicked off
body: <p>I'd like to know whether I'm able to propagate environment variables from a file.</p>
  
  <p>Guess I have a file like this:</p>
  
  <pre><code>ENV_VARIABLE_USERNAME=username
  ENV_VARIABLE_PASSWORD=password
  </code></pre>
  
  <p>I'd like when I pod kicks off, this content file is propagated as environment variables.</p>
  
  <p>Is it possible?</p>