the steps I took:</p>
<ol style="list-style-type: decimal">
<li>Construct a <code>Dockerfile</code> in a folder with any other files or dependencies, such as cron</li>
<li>Use <code><a href="../reference/docker_build.html">docker_build()</a></code> or <a href="https://cloud.google.com/container-builder/docs/concepts/creating-build-triggers">Google Container build triggers</a> to build and save your custom Docker image</li>
<li>Launch a VM using the <code>dynamic_image</code> argument to load from the custom