Dynamic resolver and proxy pass for nginx

gistfile1.txt

http {
  resolver 127.0.0.11 valid=1s;

  server {
    listen 80;
    set $foo "http://foo:80";
    set $bar "http://bar:80";

    location /foo/ {
      rewrite ^/foo/(.*) /$1 break;
      proxy_pass $foo;
    }
    location /bar/ {
      rewrite ^/bar/(.*) /$1 break;
      proxy_pass $bar;
    }
  }
}

// Wanting http://localhost:80/foo/controller => http://foo:80/controller
// Wanting http://localhost:80/bar/controller => http://bar:80/controller
// Observed (404) => http://localhost:80/controller