Cluster singleton pattern

Continuing the series on distributed Elixir, let’s talk about how to safely run a single instance of a process in a cluster. Well, as safe as we can make it. There's also an incredible cluster related murder mystery story if you continue reading! But first, if you haven’t read Chris Keathley’s The dangers of the Single Global Process you should probably do that before you continue, to tackle the caveats of trying to run a single global process. If you’re into that kind of reading, also take a look at To spawn, or not to spawn? by Saša Jurić. I’ll just let those articles explain how to think about trying to run a single global process, and the risks that that brings. There are times when a single global process is genuinely the best path forward though, or to be perfectly honest, where it’s the lesser evil. As long as you’re aware of the trade offs you’re making, there's no reason why you can’t make them. Running a single global process in a single node environment is straightforward…