Phoenix.PubSub in an umbrella app -- Phoenix in Action 1.4

[al2o3cr]

Past me FTW

Application start up fail cause by unclear reason: failed to start child: ChatWeb.Endpoint

The problem is the applications key - if it’s not supplied at all, you get the built-in behavior where all of the applications listed in deps are started automatically. If you supply a value, the runtime assumes you know what you are doing and ONLY starts those applications - so things like ranch which aren’t listed don’t get started, and you get the error you’re seeing. A good writeup about the difference between applications and extra_applications from a while back.