<p>Should I worry about leaving my container dirty? For example if I create files every time it's run, should I delete these files at the end of the job?</p>

throwaway919
<p>Every file you create will be deleted when the job finishes unless you mount a persistent volume, that way you can share data between subsequent runs of the same job.</p>
<p>So, you shouldn't worry to delete the files you created unless they are bigger than ~40GB</p>
<hr />
<p>Additional resources:</p>
<ul>
<li><em><a href="https://kubernetes.io/docs/concepts/storage/volumes/" rel="nofollow noreferrer">Kubernetes.io: Docs: Concepts: Storage: Volumes</a></em></li>
</ul>
<blockquote>
<p>On-disk files in a container are ephemeral, which presents some problems for non-trivial applications when running in containers. <strong>One problem is the loss of files when a container crashes. The kubelet restarts the container but with a clean state.</strong> (this applies to newly created <code>Jobs</code> too).</p>
</blockquote>
<ul>
<li><em><a href="https://kubernetes.io/docs/concepts/workloads/controllers/job/" rel="nofollow noreferrer">Kubernetes.io: Docs: Concepts: Workloads: Controllers: Job</a></em></li>
</ul>
<blockquote>
<p>A Job creates one or more <strong>Pods</strong> and will continue to retry execution of the Pods until a specified number of them successfully terminate.</p>
</blockquote>
