server {
     listen 80;
     server_name localhost;
 
     #charset koi8-r;
 
     #access_LOG logs/host.access.log main;
 
     location / {
     root htML;
          index index.html index.htm;
     }
     location /lua {
          default_type text/plain;
          content_by_lua_file /opt/lua/bin/test.lua;
     }
     ........
}

local welcome = 'Hello World'
ngx.say(welcome)