On Fri, Jan 27, 2017 at 12:10 AM, sendmaildevnull <sendmaildevn...@gmail.com> wrote: > I'm trying generate a unique-id-header only if one is not already provided > in the request. If I provide the header in my request to haproxy I end up > with duplicate headers, one with auto generated header and another with the > user provided header. I attempted to use the technique mentioned here > (http://discourse.haproxy.org/t/unique-id-adding-only-if-header-not-present/67/2) > and listed below but it is not working for me. Basically, I'm unable to > check/get value for unique-id-header (e.g. req.hdr(TMP-X-Request-Id)). Any > ideas?
I have struggled with this one also, and I reached a simple (but suboptimal) solution: (A) Set an `X-HA-Request-Id` header if it doesn't already exist; (B) Configure `unique-id-*` as follows: unique-id-format %[req.hdr(X-HA-Request-Id)] unique-id-header X-HA-Request-Id-2 (I.e. in the end there are two exact headers sent to the backend, with equal values, either the original value of the `X-HA-Request-Id` header, or a random one.) BTW, I always set the request header (if it doesn't already hold a value) as a random token which would yield 128 bits of entropy, and doesn't provide any personal identifiable information. http-request set-header X-HA-Request-Id %[rand(4294967295)].%[rand(4294967295)].%[rand(4294967295)].%[rand(4294967295)] if ... Hope it helps, Ciprian. P.S.: It sure would be helpful to have some cryptographic transformation functions like the SHA2 family, HMAC-based functions, and a cryptographic random function. :)
