title: Connect Jenkins to GCP container registry
body: <p>I'm trying to connect jenkins to container registry on GCP.
  I follow some examples but I'm blocked on a simple and stupid thing.</p>
  
  <p>I have this stage in my jenkins file :</p>
  
  <pre><code>    stage('Push image') {
        docker.withRegistry('https://eu.gcr.io', 'gcr:[my-credentials]') {
          app.push("${env.BUILD_NUMBER}")
          app.push("latest")
        }
  }
  </code></pre>
  
  <p>But I don't have any idea which credential put there... </p>
  
  <p>I try to create on GCP -> API&amp;Service -> Credentials -> Create Credential -> Service Account Key</p>
  
  <p>Download the json and add it to Jenkins, on piplene field I use: name of project, credential id, and so on, but it doesn't work.</p>