[DOCS] Describe the role of use_proxy_proto: true in Envoy sample config 👺👺👺

[paoloantinori]

Hi there.
In a quest to make Limitador working on OpenShift, I have spent some good hours trying to understand what I was doing wrong in adapting the kubernetes example.

It turned out that the source of the issue was use_proxy_proto: true !!!

I've searched in your repo and I have found a reference to that in the kind setup script: https://github.com/3scale-labs/limitador/blob/ace7dd773300b8ab76d95a528380dd3cf53a531e/limitador-server/script/kind-setup.sh

My suggestion would be to mention it's role explicitly in the docs with the correct setting required.

FWIW, this is the output from curl when the flag is set to true:

curl: (52) Empty reply from server

[davidor]

The instructions that we have in https://github.com/3scale-labs/limitador/tree/master/limitador-server/kubernetes describe how to deploy on AWS via an ELB. In that case, use_proxy_proto needs to be set to true as specified in the Envoy docs:

use_proxy_proto

(BoolValue) Whether the listener should expect a PROXY protocol V1 header on new connections. If this option is enabled, the listener will assume that that remote address of the connection is the one specified in the header. Some load balancers including the AWS ELB support this option. If the option is absent or set to false, Envoy will use the physical peer address of the connection as the remote address.

That's why it's set to true in the templates, but in the script that uses Kind is set to false.

I agree that this should be documented in the README linked above.