title: Set up environment variable ionic 3
body: <p>I try many way to set up environment variables in ionic3:  </p>
  
  <blockquote>
    <p><a href="https://b-nova.com/ionic2/2017/04/01/environment-config-managenemt-ionic2.html" rel="nofollow noreferrer">ENVIRONMENT VARIABLES IN IONIC 2</a><br>
    <a href="https://www.williamghelfi.com/blog/2017/06/22/ionic-environments-webpack/" rel="nofollow noreferrer">How to set up environment specific configurations with Ionic and Webpack</a><br>
    <a href="http://roblouie.com/article/296/ionic-2-environment-variables-the-best-way/" rel="nofollow noreferrer">Ionic 2 Environment Variables: The Best Way</a></p>
  </blockquote>
  
  <p>But each solution failed on my project.<br>
  The <code>process.env.IONIC_ENV</code> is always equal to <code>dev</code> even if I do <code>ionic serve --prod</code> or something else.<br>
  I don't understand why... Am I doing something wrong or forget to do something? And by the way which of this solution is the more flexible?</p>