load_balancer.conf

#
# Proxy / load balancer for public API.
#

# Hosts we will load balance between. Doesn't matter
# which ports you use, however remote servers in the
# pool should also be proxied to filter requests, to
# only allow connections from this load balancer for
# example. 
upstream server_pool {
    server localhost:port;
    server 002.xxx.yyy.zzz;
    server 003.xxx.yyy.zzz;
    server 004.xxx.yyy.zzz:port;
    server 005.xxx.yyy.zzz;
}

# Incoming requests will be served on port 80, but 
# could be any unused port you like. Using port 80
# insures widespread access through most firewalls
# and makes for a  cleaner connection string like:
#          wss://baxters-sports.net/ws
server {
    listen 80;
    server_name _;
    root /var/www/html/;

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    keepalive_requests 100000;

    # Default location match - will drop all connections
    # immediately without responding if websocket location 
    # below fails to match.
    location / {
        return 444;
    }

    # Matches websocket URL address 
        location ~ ^/ws$ {
        limit_req zone=ws burst=5;

        proxy_http_version 1.1;
        proxy_connect_timeout 2;
        proxy_pass http://server_pool;

        proxy_set_header Host $host;
        proxy_set_header Connection "upgrade";
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

        proxy_next_upstream error timeout invalid_header http_500;
    }
}