I have a VM running Docker, which means that nothing else is running, but I'm having docker just exit. I actually tracked down the error, and it looks like some host or docker periodic command that sends the webserver a HUP signal. Upon seeing the HUP, it cycles the web server -- but bringing down the web server makes the container stop too. Help with why containers exit

Edit: Looking back, I don't think that the containers just exited; I think a memory or disk space crunch might have inspired a signal being sent to the main process, causing it to die. Why do I think this? Because I had these containers up for a few weeks without a repeat. Might be worth doing a circle-back at some point to check.