nginx.conf

user www-data;
worker_processes  1;
error_log  /var/log/nginx/error.log error;
pid        /var/run/nginx.pid;
events {
    worker_connections  61440;
}

http {
    access_log  off;

    lua_shared_dict ngx_stats 10m;
    lua_package_path '/etc/nginx/lua/?.lua;;';
    lua_package_cpath '/etc/nginx/lua/?.so;;';
    init_by_lua_file /etc/nginx/lua/stats/init.lua;

    proxy_cache_path /var/tmp/cache_http levels=1:1:1
        keys_zone=g_cache:64m
        max_size=1024m inactive=4h;

    server {
        listen 80;
        server_name example.com;
        set $stats_group "example.com";
        log_by_lua_file /etc/nginx/lua/stats/log.lua;
        location / {
            proxy_pass "http://127.0.0.1:8080";
            proxy_cache g_cache;
        }
        location = /status.json {
            default_type 'application/json';
            content_by_lua_file /etc/nginx/lua/stats/show.lua;
        }
    }
    server {
        listen 80;
        server_name  sub.example.com;
        set $stats_group "sub.example.com";
        log_by_lua_file /etc/nginx/lua/stats/log.lua;
        location / {
            proxy_pass "http://127.0.0.1:8081";
            proxy_cache g_cache;
        }
    }
    server {
        listen 80 default_server;
        server_name  _;
        log_by_lua_file /etc/nginx/lua/stats/log.lua;
        return 404;
    }
}