add_header X-Cache $upstream_cache_status;
http://zyan.cc/nginx_cache/2/1/
http://linux.it.net.cn/e/server/nginx/2015/0314/13930.html
http://www.dnzsb.com/article-3943-1.html
1）./configure: error: ngx_http_lua_module requires the Lua library.
解决方法：
yum install -y lua-devel
sudo apt-get install libluajit-5.1-dev
http://stackoverflow.com/questio … h-lua-on-rpm-system
