title: Docker-in-Docker with Gitlab Shared runner for building and pushing docker images to registry
body: <p>Been trying to set-up Gitlab CI which can build a docker image, and came across that DinD was enabled initially only for separate runners and <a href="https://about.gitlab.com/2016/05/23/gitlab-container-registry/" rel="noreferrer">Blog Post</a> suggest it would be enabled soon for shared runners, </p>
  
  <p>Running DinD requires enabling privileged mode in runners, which is set as a flag while registering runner, but couldn't find an equivalent mechanism for Shared Runners</p>