Add support for writing PROXY protocol v2 to upstream

[ko.cloudflare.com@…]

With nginx 1.13.11, support for reading version 2 of the PROXY protocol (the binary variant) was added. However, nginx also allows to write the PROXY protocol to a TCP upstream with the "proxy_protocol on;" setting in a server block. However, it seems like this is always version 1. (Implemented as ngx_proxy_protocol_write in ngx_proxy_protocol.c.)

It would be great if version 2 would be supported as well. Maybe configurable by specifying an integer in the configuration "proxy_protocol 2;". Are there any plans to implement this?

[Maxim Dounin]

This was considered (and I believe there was a patch), yet there were no compelling reasons to add support was identified. As such, it was postponed till there will be some reasons identified (if at all).

The main reason for the client-side PROXY protocol version 2 support was Amazon NLB, which can only use PROXY protocol version 2.

[ko.cloudflare.com@…]

I guess the main reason would be that it's faster to parse, especially with IPv6 addresses. I can't find a patch in the mailing list archive.

[Maxim Dounin]

I guess the main reason would be that it's faster to parse, especially with IPv6 addresses.

In our practice, version 1 is actually much easier to parse. As for the speed, I haven't seen any numbers - likely because it's not something measurable compared to the connection consts.

I can't find a patch in the mailing list archive.

This was an internal patch, it wasn't in the mailing list.

[ko.cloudflare.com@…]

Fair enough. I also don't have any numbers at the moment and I guess I can live with v1 for the time being. I guess this can be closed. Thanks for your replies!