Nginx Load balance + Health check

.nginx

user root;
worker_processes auto;
worker_rlimit_nofile 1048576;
pid /run/nginx.pid;

events {
    worker_connections 1048576;
    use epoll;
    multi_accept on;
}

http {
    include /usr/local/nginx/conf/mime.types;
    default_type application/octet-stream;

    error_log /usr/local/nginx/logs/error.log debug;
    error_log /dev/stdout warn;

    lua_shared_dict healthcheck 1m;

    upstream casts {
        include upstream_servers.conf;
    }

    init_worker_by_lua_block {
        local hc = require "resty.upstream.healthcheck"
        local upstream = require "ngx.upstream";

        local upstreams = upstream.get_upstreams()
        local healthCheckArgs = {
            shm = "healthcheck",  -- defined by "lua_shared_dict"
            type = "http",
            interval = 5000,  -- Check every 5 sec
            timeout = 1000,   -- 1 sec is the timeout for network operations
            fall = 3,  -- # of successive failures before turning a peer down
            rise = 2,  -- # of successive successes before turning a peer up
            valid_statuses = {200, 302},
        }

        for ix, upstream_name in ipairs(upstreams) do
            ngx.log(ngx.INFO, 'Current upstream', upstream_name)

            local servers = upstream.get_servers(upstream_name)
            local totalServers = table.getn(servers)

            healthCheckArgs.upstream = upstream_name;
            healthCheckArgs.http_req = "GET /status HTTP/1.0\r\nHost: " .. upstream_name .. "\r\n\r\n";
            healthCheckArgs.concurrency = totalServers;

            local ok, err = hc.spawn_checker(healthCheckArgs)
            if not ok then
                ngx.log(ngx.WARN, "failed to spawn health checker: ", err)
                return
            end
        end
    }

    server {
        location / {
            proxy_pass http://shoutcast;
            proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_429 http_403 http_404;
        }

        location /status {
            access_log off;
            allow 127.0.0.1;
            deny all;

            default_type text/plain;
            content_by_lua_block {
            local hc = require "resty.upstream.healthcheck"
                ngx.say("Nginx Worker PID: ", ngx.worker.pid())
                ngx.print(hc.status_page())
            }
        }
    }
}

upstream_servers.conf

server 127.0.0.2:8004;
server 127.0.0.3:8006;
server 127.0.0.4:8005 backup;