upstream redmine {
        server 127.0.0.1:8000;
        server 127.0.0.1:8001;
        server 127.0.0.1:8002;
}

server {
        server_name redmine.DOMAIN.TLD;
        root /var/www/redmine/public;

        location / {
                try_files $uri @redmine;
        }

        location @redmine {
                proxy_set_header  X-Forwarded-For $remote_addr;
                proxy_pass http://redmine;
        }
}