Mithril Monitoring and Shutdown on Absence of node.socket

[conraddit]

Presently, if the Mithril app stops running, there is no way to identify that it stopped other than looking at syslog. Given the importance of the app, it'd be great if there were a TCP port that remains open while the app is running, simply for monitoring purposes, so that we can nmap to it every few seconds to determine that it's running.

Additionally, I believe that it could be helpful if the Mithril app were to automatically exit on the absence of Cardano Node's node.socket is missing. I.e., if Cardano Node stop, Mithril would detect that node.socket was missing and would also stop. Ogmios and Kupo do this.

Combined, we'd have means to externally verify that Mithril was running and in the event of an outage with Cardano Node, Mithril would also go offline, giving us almost immediate feedback to troubleshoot.