Sticky Session with an assignable backend

Oddur Snær Magnússon oddur at
Wed Oct 24 19:50:44 CEST 2012

Unfortunately its 'a REST APi which does not support cookies. 

I'm attempting to get it working as a proof of concept using this vmod	arnish/libvmod-var 

I might extend it to support a hashtable for efficient lookups. 

-----Original Message-----
From: Lasse Karstensen [mailto:lasse.karstensen at] 
Sent: Tuesday, October 23, 2012 11:19 AM
To: Oddur Snær Magnússon
Cc: varnish-misc at
Subject: Re: Sticky Session with an assignable backend

Oddur Snær Magnússon:
> I have a problem where I need to be able to do "sticky session" based on some identity, but be able to tell varnish which identity belongs to which backend.
> In my case, I have a value in the request header(oauth token) which should always go to the same backend. I begin by sending the request to a random backend, and if the users session does not live on that backend I get X-Accel-Redirect header back telling me which backend that request should go to.  I can easily do that part using a restart and send the request to the correct one.
> But  from then on I want to remember that that specific identity should always go to that given backend.

Given that the HTTP client supports it, I'd just put the backend information into a client side cookie. 

Send a set-cookie in deliver, and extract/remove it in recv on the next request.

Lasse Karstensen
Varnish Software AS

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