[undersuit]

That sounds like a fixable problem. I'm pretty sure Erlang programmers could give some tips.

Why is worrying about a single web server going down more worrisome than some part of the Docker stack going down and causing the same issue?

[titpetric]

Actually, neither should be a problem if you have enough redundancy :) the hardest part of rolling your own infrastructure is testing mission critical systems (like databases) to be fault tolerant and at the same time reliable. Lots of great projects are out there that address some of these issues, but it takes a lot of attention to details (like transaction rates, ACID compliance, replication, etc.) to get it right. This is why a lot of developers which aren't in unicorn startups take advantage of technology which is available from giants like Amazon or Google, or specific problem-domain companies like CloudFlare for example. Netflix serves as a great example of a technology-driven company that is an inspiration to us, but there are so many others that really changed the way we approach problems - Tumblr, Etsy. But to stay on topic of netflix - I think their idea behind "chaos monkey" is great, and we're increasingly rolling out a (currently simple) docker swarm version of it - https://github.com/titpetric/docker-chaos-monkey - the best way to eliminate worry is to test failure scenarios. As docker chaos monkey is designed to unpredictably "kill off" containers, your system gets the benefit of design to handle failures. It's one of those problems that you have to have a passion for however - it's like testing software. You're only testing software for the functionality and failures which you can predict, and I'm pretty sure that any of us can't predict all the ways in which software (or distributed systems) can fail. As such, it's a never ending occupation. :)