刚刚接触Varnish缓存，对静态资源进行缓存。目前问题，当浏览器Control+F5刷新页面，导致缓存失效、
参照：http://zhangxugg-163-com.iteye.com/blog/1075206 修改下Varnish配置
sub vcl_hit {
#if (req.http.Cache-Control ~ "no-cache") {
# if (! (req.http.Via || req.http.User-Agent ~ "bot|MSIE")) {
# set obj.ttl = 0s;
# return (restart);
# }
#}
return(deliver);
}