title: how to trigger a jenkins pipeline stage when an authorized user make a comment on github pull request?
body: <p>I am familiar with <a href="https://wiki.jenkins-ci.org/display/JENKINS/GitHub+pull+request+builder+plugin" rel="nofollow noreferrer">Jenkins Pull Request Builder</a> and I had set up a freestyle job with it to build my project based on the comment that authorized user put. (For example <code>test in prod</code>) in the past.</p>
  
  <p>Now I am trying to use a Jenkins 2.0 with github organization plugin for one of my project.</p>
  
  <p>this is the scenario:</p>
  
  <ol>
  <li>A User is making a PR to master(or some other sensitive branch)</li>
  <li>A test is going to get run automatically.</li>
  <li>After the test past, an authorized user needs to go to the PR and put a comment <code>Deploy to test environment</code> and then  a jenkinsfile that was waiting for this input needs to get trigger.</li>
  </ol>
  
  <p>I just dont know how to do the step 3. how do I make jenkins pipeline job listen for comments in github repo pull requests? the Jenkins documentation is not really clear about the input from user part.</p>
  
  <p>I read <a href="https://stackoverflow.com/questions/36850485/how-to-trigger-a-jenkins-2-0-pipeline-job-from-a-github-pull-request">this</a> thread answer but the documentation about the Gates approval is really limited.</p>