I've once built a distributed scheduler to run PHP jobs over a cluster of several thousand machines, before Kubernetes was a thing. It's only a few thousand lines of code and perfectly matches the description of being terrible, hacked together, etc. It also rarely broke and the company still uses it to this day, 10 years later, with almost no adjustments. My ex-colleagues are also saying that wherever they go they miss that framework (even though it's technically open source). And yes, I'm Russian :).