title: Creating a docker image by merging 2 images
body: <p>Is there a way to merge 2 docker images into a single one? I want to setup a gitlab-ci server. For this, I need to setup a runner able to build a maven project on Java 8. There are actually an image to setup a <a href="https://hub.docker.com/r/sameersbn/gitlab-ci-runner/" rel="nofollow">generic gitlab-ci runner</a> and another one that has <a href="https://hub.docker.com/_/maven/" rel="nofollow">maven and Java 8</a> support. If I could combine both of these images, I could easily achive my goal.</p>