I’m getting an http status code 431 on reverse proxy requests that should be going to a mock server that we control. According to the mock server logs, it never receives the requests. Debug Caddy logs show that Caddy is returning a 431 status despite having the server configured with max_header_bytes set to a very large size.
Is the 431 status coming from a Go library dependency? Is there a way to increase headers to allow for very large cookies on reverse proxy requests? We own all of the domains that are the target of the proxying.
4. Error messages and/or full log output:
On any reverse proxy upstream request, I get a 431 Request Header Fields Too Large status, that goes away if I delete some of the cookies.
5. What I already tried:
I’ve tried various values for the max_header_bytes setting on the server, but none of them have had an effect. The largest size I specified on the server config was: