Switching backends based on a cookie

[saltyflorida]

Is it possible to switch backend clusters of servers based on a cookie?

I would like to set a cookie named "env" and do something like this:

        if ($http_cookie ~* "env=testing(;|$)") {
            proxy_pass http://backend_testing;
        }
        if ($http_cookie ~* "env=staging(;|$)") {
            proxy_pass http://backend_staging;
        }
        if ($http_cookie ~* "env=production(;|$)") {
            proxy_pass http://backend_production;
        }

However the "proxy_pass" directive is not allowed inside an "if". Is there another way I can approach this?

Thanks,
Eliot

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,46979,46979#msg-46979