It's definitely nice when it does but it's also a whole lot of complexity to add to the code. You have to re-create all structures relying on configs, reconnect if needed, clear all previous ones, but only after any ongoing processing of requests received before the reload signal finishes.
Some go half-way, like HAProxy where it does spawn a new process but that process just binds with SO_REUSEPORT and signal old one to close the socket and finish all remaining connections. So you effectively get hitless reload, it's just that old process is the one finishing in-flight requests
Yeah, it def adds complexity but if you want it used in real world applications, it’s a must-have. With only env vars, it’s an impossibility to ever have (without supporting infrastructure and processes), which was the point I was trying to make.
Hardly. "Real world applications" need to tolerate single node failure anyway so reload functionality doesn't add all that much. Some system daemons, sure, them not working for a second can be disruptive so it is worthy endeavor there, but the amount of added complexity is nontrivial and the added complexity scales with apps' own complexity.
It's a bit different for desktop apps, as restarting app every time you change some config options would be far bigger PITA than some server app.
Unless you’re working for a tech company, it’s running on a single server (and it’s worth pointing out that most companies aren’t tech companies). That’s what I meant by “real world”, AKA, outside the tech bubble.
Some go half-way, like HAProxy where it does spawn a new process but that process just binds with SO_REUSEPORT and signal old one to close the socket and finish all remaining connections. So you effectively get hitless reload, it's just that old process is the one finishing in-flight requests