Implement debug logging in Cowboy the same way the ssl does

[essen]

See http://blog.erlang.org/ssl-logging-in-otp-22/ for a full description.

One could enable debug logging in Cowboy to see all the packets transmitted and what Cowboy thinks of them, something like that. Could make some client issues obvious in particular.

[essen]

Also nghttp -v has some pretty good debug logging. Maybe do something similar.

[fredr]

This would be very useful for debugging http2 frames, especially when the service is behind a proxy, and you need to debug frames sent between the backend and the proxy

[jordanfranssen]

My organization would be particularly interested in logging HTTP headers.

This article gives the guidelines we desire to meet: https://www.stigviewer.com/stig/application_security_and_development/2017-12-18/finding/V-69375

[essen]

@jordanfranssen This ticket in particular is about debug logging. It's not meant to be used in production.

If I had to implement HTTP headers logging from scratch I would use cowboy_metrics_h because it keeps track of everything: https://ninenines.eu/docs/en/cowboy/2.8/manual/cowboy_metrics_h/ but since rabbitmq-management already has some access logging maybe you're looking into adding the information to these logs instead.

If you are not familiar with Erlang I am available for consulting or development. I am the author of Cowboy and also work with the RabbitMQ team on a regular basis, so I'm sure I can arrange something depending on your needs. I've done a lot of work on rabbitmq-management. You can find more information about the services I provide and a contact email at https://ninenines.eu/services/