title: Dockerfile entrypoint failing in Jenkins pipeline
body: <p>How does the Jenkins <code>Dockerfile</code> agent work?</p>
  <p>I've defined my Dockerfile as</p>
  <pre><code>FROM hashicorp/terraform:latest
  ENTRYPOINT [&quot;terraform&quot;]
  </code></pre>
  <p>And my Jenkinsfile as</p>
  <pre><code>pipeline {
      agent { 
          dockerfile true
      }
      stages {
          stage('Example') {
              steps {
                  sh 'terraform version'
              }
          }
      }
      post { 
          always { 
              cleanWs()
          }
      }
  }
  </code></pre>
  <p>But I keep getting an error in the console output asking me to check my <code>ENTRYPOINT</code></p>
  <p>ErrorMessage:</p>
  <pre><code>ERROR: The container started but didn't run the expected command. Please double check your ENTRYPOINT does execute the command passed as docker run argument, as required by official docker images (see https://github.com/docker-library/official-images#consistency for entrypoint consistency requirements).
  Alternatively you can force image entrypoint to be disabled by adding option `--entrypoint=''`.
  </code></pre>
  <p>I've looked at the <a href="https://github.com/docker-library/official-images#consistency" rel="nofollow noreferrer">documentation</a> but I can't seem to make sense of it.</p>
  <p>What I expect to happen is that Jenkins will build the <code>hashicorp/terraform</code> image which I can then use as a build agent without having to install terraform on my server, but I seem to be doing something wrong.</p>
  <p>Does anyone understand how this works?</p>