高性能缓存服务器Varnish架构配置

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    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：

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#!/bin/sh #auto install varnish #2014-07-28 by wugk DIR=/usr/src CODE=$? VER=$1 if  [ -z $1 ];then     echo "Usage:{$0 'Version' install |config |start|help } , Example $0 2.1.5 install}"     exit fi URL=https://repo.varnish-cache.org/source/varnish-${VER}.tar.gz function install() { if  [ ! -d /usr/local/varnish -o ! -f /etc/init.d/varnishd ];then     cd $DIR ;wget -c $URL     if  [ $CODE == '0' ];then         echo "This varnish Files is Download Successed!"     else         echo "This varnish Files is Download Failed!"     fi     useradd  -s /sbin/noin varnish     mkdir -p /data/varnish/{cache,}     chown -R varnish.varnish /data/varnish/     tar xzf varnish-${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 else     echo "This Varnish is exists,Please exit..."     sleep 1     exit 0 fi } function config() {     if  [ ! -d /usr/local/varnish/ -o -f /etc/init.d/varnishd ];then               echo "You can't config varnish ,Please ensure you varnish dir is or not exist..."         exit 0     else                   echo "Varnish Already Success Install ,Please Config varnish ......"     fi     mv /usr/local/varnish/etc/varnish/default.vcl /usr/local/varnish/etc/varnish/default.vcl.bak     cat >>/usr/local/varnish/etc/varnish/default.vcl <<EOF backend 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); } EOF if [ $? == 0 ];then     echo '----------------------------------'     sleep 2     echo "This Varinsh Config Success !!!" else     echo "This Varinsh Config Failed,Please Check Conf!" fi } function start() { if  [ ! -d /usr/local/varnish -o -f /etc/init.d/varnishd ];then     echo "You can't config varnish ,Please ensure you varnish dir is or not exist..."     exit 0 else     count=`ps -ef |grep varnishd|grep -v grep |wc -l`     if [ $count -eq 0 ];then         echo "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.pid         if [ $? == 0 ];then             echo "Start varnish ...OK"         fi     else         echo "Warning,This Varnish Service is exist."     fi fi } case $2 in     install)     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

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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：

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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。