title: Node-config won't use variables from custom-environment-variables.json in Heroku
body: <p>I'm using the node-config module for mongo connection strings and jwt keys.</p>
  
  <p>For example:</p>
  
  <pre><code>if(!config.get('jwtPrivateKey')){
      throw new Error('FATAL ERROR: jwtPrivateKey is not defined');
  </code></pre>
  
  <p>My <code>custom-environment-variables.json</code> file looks like:</p>
  
  <pre><code>{
      "jwtPrivateKey": "video-app_jwtPrivateKey",
      "db": "video-app_db"
  }
  </code></pre>
  
  <p><code>default.json</code></p>
  
  <pre><code>{
      "db": "default db",
      "jwtPrivateKey": "default key"
  }
  </code></pre>
  
  <p><code>production.json</code></p>
  
  <pre><code>{
      "db": "production db",
      "jwtPrivateKey": "production key"
  }
  </code></pre>
  
  <p>long story short - although the environment variables are set in heroku, node-config doesn't look at the values set in <code>custom-environment-variables.json</code>. I can alter the NODE_ENV and get the relevant json file's hardcoded values, but the environment variables are never used, which seems to contradict the docs</p>