When I woke up this morning, the app had crashed because the mysql connection was closed!
I'm not sure, why that caused a _crash_? Or why pm2 didn't pick up on it, and said the process was still online? (Maybe the process was running, but the server had stopped?) Those could be good to investigate?…
…but better than diving too far into the details, is to just address the high-level problem: if the app goes down for unexpected reasons, I want it back up!! lol
In this change, we add `monit`, a solid system for monitoring processes (including checking for behavior, like responding to net requests), and configure it to watch the app process and the nginx process.
To test, you can run `pm2 stop impress-2020`, or `systemctl stop nginx`, to see that Monit brings them back up within seconds!
This does add some potential surprise if you're _trying_ to take the processes down. The easiest way is to send the stop command through monit, like `monit stop nginx`. This will disable monitoring until you start it again through monit, I think? (You can also disable/enable monitoring as a direct command, regardless of app state.)
You can see how, instead of the default experience where certbot edits your config for you, I've referenced the certificates in the config in the first place, and set up certbot to just generate them!
Also, I learned about certbot non-interactive mode! At first I wrote this with the Ansible `expect` module lol :p
