Nginx thumbor configuration

thumbor.conf

upstream thumbor  {
server 127.0.0.1:8090;
server 127.0.0.1:8091;
server 127.0.0.1:8092;
server 127.0.0.1:8093;
}

server {
    listen       80;
    server_name  thumbor.domain.com;
    client_max_body_size 50M;
    access_log  /var/log/nginx/thumbor-access.log;
    error_log  /var/log/nginx/thumbor-error.log;


    location ~* "^/(..)(..)(.+)?$" {
        root        /thumbor/path/result_storage/v2/$1/$2;
        expires     1M;
        error_page  404 = @fetch;
    }

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

Hey ! I'm trying to do a simple thumbor setup , my thumbor dir is /home/thumbor
And nginx config is

upstream thumbor  {
    server 127.0.0.1:8000;
    server 127.0.0.1:8001;
    server 127.0.0.1:8002;
    server 127.0.0.1:8003;
}

server {
    listen       80;
    server_name  cdn.domain.org;
    client_max_body_size 10M;

    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header HOST $http_host;
        proxy_set_header X-NginX-Proxy true;

        proxy_pass http://thumbor$request_uri;
        proxy_redirect off;
    }
}

And I'm running into no upstream found nginx error. Can't find a fix around that , any help would be appreciated . Thanks