gistfile1.txt

        upstream thumborbe {
            server thumbor.myhost.com:8090 ;
            server thumbor.myhost.com:8091 ;
            server thumbor.myhost.com:8092 ;
            server thumbor.myhost.com:8093 ;
            server thumbor.myhost.com:8094 ;
            server thumbor.myhost.com:8095 ;
        }

        location ~* "^/(..)(..)(.){24}/.*(jpg|jpeg|gif|png)(#.*)?$" {
            root        /path/to/your/thumbor/generated/images/$1/$2;
            expires     1M;

            error_page  404 = @fetch;
        }

        location @fetch {
            internal;
            proxy_pass http://thumborbe$request_uri;
        }