Thankyou Willy. http-send-name-header works for my use case. @Norman - Yes, we are looking at replacing the usage of X- headers.
Thanks Sachin On Mon, Dec 17, 2018 at 2:18 AM Norman Branitsky < [email protected]> wrote: > Don't forget the "X-" header prefix is deprecated: > https://tools.ietf.org/html/rfc6648 > > Norman Branitsky > > On Dec 16, 2018, at 03:50, Willy Tarreau <[email protected]> wrote: > > Hi Sachin, > > On Sat, Dec 15, 2018 at 10:32:21PM +0530, Sachin Shetty wrote: > > Hi, > > > We have a tricky requirement to set a different header value in the request > > based on which server in a backend is picked. > > > backend pod0 > > ... > > server server1 server1:6180 check > > server server2 server2:6180 check > > server server3 server3:6180 check > > > so when request is forwarded to server1 - I want to inject an header > > "X-Some-Header: Server1", "X-Some-Header: Server2" for server 2 and so > > on. > > > You have this with "http-send-name-header", you need to pass it the > header field name and it will fill the value with the server's name. > It will even support redispatch by rewinding the stream and rewriting > the value (which made it very tricky and infamous for quite some time). > > If it possible to register some lua action that would inject the header > > based on the server selected before the request is forwarded to the > server. > > > In fact except for the directive above it's not possible to perform > changes after the server has been selected, because the server is > selected when trying to connect, which happens after the contents are > being forwarded, thus you can't perform any processing anymore. There > is quite some ugly code to support http-send-name-header and it cannot > be generalized at all. Just to give you an idea, think that a hash-based > LB algo (balance uri, balance hdr) could decide to use some contents > you're about to modify... So the contents have to be fixed before the > server is chosen. > > Cheers, > Willy > >
