title: How to make configuration fields required in Viper?
body: <p>I use Viper <a href="https://github.com/spf13/viper" rel="noreferrer">https://github.com/spf13/viper</a> for managing project configurations in my GO app, and also for Unmarshaling configuration values to a struct.</p>
  <pre><code>var config c.Configuration // Configuration is my configuration struct
  
  err := viper.Unmarshal(&amp;config)
  </code></pre>
  <p>When I miss some configs in .yml config file it doesn't throw any error (as I had guessed) during Unmarshaling.</p>
  <p>So how can I force to have all configs implemented? I want to see errors if any field from struct doesn't have value in yaml.</p>