Nginx Load Balancing

nginx.conf

user  www-data;
worker_processes auto;

events {
    worker_connections  1024;
}

http {
    include       mime.types;
    default_type  text/html;

    log_format  loadbalancer  'Request "$request" - Upstream [Addr: $upstream_addr $upstream_http_name, Status: $upstream_status]';

    index   index.html index.htm index.php;
    charset utf-8;
    gzip    on;

    # upstream backend
    upstream backend {
        zone backend 64k;

        server backend1.dev:8081;
        server backend2.dev:8082;
        server backend3.dev:8083;

        server backup1.dev:8084 backup;
    }

    # load balancer
    server {
        listen      80;
        server_name lb.dev;

        access_log  /var/log/nginx/lb.access.log loadbalancer;

        proxy_next_upstream         error timeout http_500 http_502 http_503 http_504;
        proxy_next_upstream_timeout 2s;
        proxy_read_timeout          2s;
        proxy_connect_timeout       2s;

        location /upstream_conf {
            upstream_conf;
        }

        location = /status.html {
            root /usr/share/nginx/html;
        }

        location = /status {
            status;
        }

        location / {
            # Rewrite the 'Host' header to the value in the client request or primary server name
            proxy_set_header Host $host;

            proxy_pass http://backend;

            health_check interval=3s fails=1 passes=3 uri=/ping match=statusok;
        }

        # static
        location ~* \.(css|js|ico|png|gif|jpg|jpeg|svg|eot|ttf|woff|woff2)$ {
            access_log      off;
        }
    }

    match statusok {
        status 200;
    }

    # backend servers
    # simulate custom configs, take down/up, timeout, etc.

    server {
        listen       8081;
        server_name  backend1.dev;

        location ~ ^/(status|ping)$ {
            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }

        location / {
            root    /var/www/html;
            index   index.php;
            fastcgi_index index.php;

            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }
    }
    server {
        listen       8082;
        server_name  backend2.dev;

        location ~ ^/(status|ping)$ {
            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }

        location / {
            root    /var/www/html;
            index   index.php;
            fastcgi_index index.php;

            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }
    }
    server {
        listen       8083;
        server_name  backend3.dev;

        location ~ ^/(status|ping)$ {
            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }

        location / {
            root    /var/www/html;
            index   index.php;
            fastcgi_index index.php;

            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }
    }
    server {
        listen       8084;
        server_name  backup1.dev;

        location ~ ^/(status|ping)$ {
            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }

        location / {
            root    /var/www/html;
            index   index.php;
            fastcgi_index index.php;

            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        }
    }
}