title: Verify the files as per commit in gitlab (Validation on file level)
body: <p>I have a config repository in git wherein each field I store different config parameters such as Boolean, email, text values.</p>
  <p>I want to understand if there is a way I can use gitlab QA tools to make sure none of my developers/users commit wrong values to such files.</p>
  <p>Eg: I have a file named applicationOnline and its value can be true or false. But if a user enters False or fales instead of false my application would break. Similarly, there are a few JSON which I would want to validate before commits.</p>
  <p>Please let me know how I can perform such validations before a code is committed in gitlab or point me to right documentation.</p>