<p>For example if a kubernetes cronjob runs and saves a file to disk, will it save on one of the containers my application is running on or will it save on a separate cronjob pod and then be destroyed?</p>

Sleepyhead.
<p>Kubernetes <code>CronJob</code> or <code>CJ</code> creates a <code>Job</code> which in turn creates a <code>Pod</code> with a container inside. Containers by nature are ephemeral in nature, meaning that any file/logs generated inside are tied to its life-cycle. As long as the container lives, those files/logs will live. They will disappear when a container terminates.</p>
<p>In short, each <code>CronJob</code> will create it's own file. If you want to persistent them permanently, attach a <code>PersistentVolume</code> (<code>PV</code>) with the <code>CronJob</code>.</p>
