Error handling in HTTP middlewares

[arthurpers86]

I’m building a simple HTTP middleware that only produces logs for monitoring purposes. I don’t want it to interfere with the requests in any way — every request should pass through the middleware and reach the application.

I’m not a Go expert, and my question is: what happens if something breaks in my plugin and the error isn’t properly handled? Will it stop the request from reaching the downstream handler? I want to make sure that the requests always go through, no matter what.

Here’s how my plugin is integrated in the Caddyfile:

		handle @web {
			route {
				my_monitoring_plugin
				reverse_proxy /* http://web:80
			}
		}

[francislavoie]

If you return an error in your handler, then the error routes will be invoked. So you can just log and suppress the error instead of returning it I guess. If a panic happens though (index out of bounds access or something like that) then the request basically dies. But those are rare because Go is a compiled language and the vast majority of things that go wrong are errors rather than panics.