Varnish跟Squid都是一款内容加速缓存服务器，我们可以使用它们来对我们的网页内容进行缓存，以此来从某个方面提高用户体验度，提升网站整体的抗压能力。

目前自建的CDN中，有很多都是基于Squid、Varnish等相关缓存软件，经过内部的二次开发实现了更好的内容加速及管理。

那今天我们一起来学习一下Varnish简单的搭建及日常的维护，深入的东西后期分享，跟大家一起来交流。这里直接上Shell脚本自动初始化并安装：

#!/bin/sh
#auto install varnish
#2014-07-28 by wugk
DIR=/usr/src
CODE=$?
VER=$1if  [ -z $1 ];thenecho "Usage:{$0 'Version' install |config |start|help } , Example $0 2.1.5 install}"exit
fiURL=https://repo.varnish-cache.org/source/varnish-${VER}.tar.gzfunction install()
{if  [ ! -d /usr/local/varnish -o ! -f /etc/init.d/varnishd ];thencd $DIR ;wget -c $URLif  [ $CODE == '0' ];thenecho "This varnish Files is Download Successed!"elseecho "This varnish Files is Download Failed!"fiuseradd  -s /sbin/noin varnishmkdir -p /data/varnish/{cache,}chown -R varnish.varnish /data/varnish/tar xzf varnish-${VER}.tar.gz ;cd varnish-${VER} ;/bin/sh autogen.sh  ;./configure --prefix=/usr/local/varnish --enable-dependency-tracking --enable-debugging-symbols --enable-developer-warnings -enable-extra-warnings &&make &&make install
elseecho "This Varnish is exists,Please exit..."sleep 1exit 0
fi
}function config()
{if  [ ! -d /usr/local/varnish/ -o -f /etc/init.d/varnishd ];thenecho "You can't config varnish ,Please ensure you varnish dir is or not exist..."exit 0elseecho "Varnish Already Success Install ,Please Config varnish ......"fimv /usr/local/varnish/etc/varnish/default.vcl /usr/local/varnish/etc/varnish/default.vcl.bakcat >>/usr/local/varnish/etc/varnish/default.vcl <<EOFbackend server_1
{
.host ="192.168.149.128";
.port = "8080";
.probe = {
.timeout = 5s;
.interval = 2s;
.window = 8;
.threshold = 5;
}
}
backend server_2
{
.host ="192.168.149.129";
.port = "8080";
.probe = {
.timeout = 5s;
.interval = 2s;
.window = 8;
.threshold = 5;
}
}
director rsver random {
{
.backend = server_1;
.weight = 6;
}
{
.backend = server_2;
.weight = 6;
}
}
acl purge {
"localhost";
"127.0.0.1";
}
sub vcl_recv
{if (req.http.host ~"^(.*).tdt.com"){     set req.backend =rsver; }  else{     error 200 "Nocahce for this domain"; }           if (req.request =="PURGE"){        if (!client.ip ~purge){           error 405"Not allowed.";        }else{return (pipe);}
}
if(req.http.x-forwarded-for)
{
set req.http.X-Forwarded-For =
req.http.X-Forwarded-For "," client.ip;
}
else
{
set req.http.X-Forwarded-For =client.ip;
}
if (req.request !="GET" && req.request != "HEAD")
{
return (pipe);
}
if (req.http.Expect)
{
return (pipe);
}
if (req.http.Authenticate|| req.http.Cookie)
{
return (pass);
}
if (req.http.Cache-Control~ "no-cache")
{
return (pass);
}
if(req.url ~"\.jsp" || req.url ~ "\.php" )
{
return (pass);
}
else
{
return (lookup);
}
}sub vcl_pipe
{
return (pipe);
}sub vcl_pass
{
return (pass);
}sub vcl_hash
{
set req.hash += req.url;
if (req.http.host)
{
set req.hash +=req.http.host;
}
else
{
set req.hash +=server.ip;
}return (hash);
}sub vcl_hit
{
if (req.request =="PURGE")
{
set obj.ttl = 0s;
error 200"Purged.";
}
if (!obj.cacheable)
{
return (pass);
}
return (deliver);
}sub vcl_miss
{
if (req.request =="PURGE")
{
error 404 "Not incache.";
}
if (req.http.user-agent ~"spider")
{
error 503 "Notpresently in cache";
}return (fetch);
}
sub vcl_fetch
{
if (req.request =="GET" && req.url ~ "\.(txt|js)$")
{
set beresp.ttl = 3600s;
}
else
{
set beresp.ttl = 30d;
}
if (!beresp.cacheable)
{
return (pass);
}
if (beresp.http.Set-Cookie)
{
return (pass);
}
return (deliver);
}
sub vcl_deliver {if (obj.hits > 0) {set resp.http.X-Cache= "HIT FROM TDTWS Cache Center";} else {set resp.http.X-Cache= "MISS FROM TDTWS Cache Center";}
return (deliver);
}EOFif [ $? == 0 ];thenecho '----------------------------------'sleep 2echo "This Varinsh Config Success !!!"
elseecho "This Varinsh Config Failed,Please Check Conf!"
fi}function start()
{
if  [ ! -d /usr/local/varnish -o -f /etc/init.d/varnishd ];thenecho "You can't config varnish ,Please ensure you varnish dir is or not exist..."exit 0elsecount=`ps -ef |grep varnishd|grep -v grep |wc -l`if [ $count -eq 0 ];thenecho "Varnish Already Success Install ,Now start varnish...."cat <<EOF------------------------------------------------------Start Varnish to listen 0.0.0.0:80.The Varnish load balancer server1(192.168.149.128 8080).The Varnish load balancer server1(192.168.149.129 8080).The Varnish Mgr address to listen 0.0.0.0:8001.The Varnish Cache DIR /data/varnish/cache .
EOF/usr/local/varnish/sbin/varnishd -n /data/varnish/cache -f /usr/local/varnish/etc/varnish/default.vcl -a 0.0.0.0:80 -s file,/data/varnish/varnish_cache.data,16G  -p user=varnish -p group=varnish -p default_ttl=14400 -p thread_pool_max=8000 -p send_timeout=20 -w 5,51200,30 -T 0.0.0.0:8001  -P /usr/local/varnish/var/varnish.pidif [ $? == 0 ];thenecho "Start varnish ...OK"fielseecho "Warning,This Varnish Service is exist."fi
fi
}case $2 ininstall)install;;config)config;;start )start;;*    )echo "Usage:{ Usage $0 version install |config |start|help }";;
esac

Varnish简单测试如下图：

1.第一张图，第一次访问没有命中，去后端服务器取数据，同时在本地缓存一份：（MISS）

2.第二张图，第二次访问，缓存服务器存在，则直接从缓存中返回：（HIT）

实际线上环境中，如果用户访问我们的网站，使用Ctrl+F5刷新，我们的缓存就会失效，因为我们配置文件里面是这么配置的，匹配浏览器头信息：

Pragma    no-cache

Cache-Control    no-cache

if (req.http.Cache-Control~ "no-cache")
{
return (pass);
}

只有注释掉这段代码或者设置只允许某个特定的IP，用户通过浏览器按Crtl+F5才不会把缓存给清除。

下面是针对某个特定的IP地址允许刷新：

acl   local {"192.168.149.128"
}
sub vcl_hit {if (!obj.cacheable) {return (pass); }if (client.ip ~ local && req.http.Pragma ~ "no-cache") {set obj.ttl = 0s;return (pass);}return (deliver);
}

由于时间的原因，文章就暂时写到这里，更多深入的东西继续分享，文章引用煮酒哥的配置，非常感谢。欢迎大家一起讨论。

http://yuhongchun.blog.51cto.com/1604432/1293169

http://zyan.cc/post/313/