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