什么是varnish缓存代理？如何安装和配置？

varnish缓存代理

varnish 缓存是 web 应用加速器，同时也作为 http 反向缓存代理。你可以安装 varnish 在任何http 的前端，同时配置它缓存内容。与传统的 squid 相比，varnish 具有性能更高、速度更快、管理更加方便等诸多优点。

varnish 完整配置实例1、拓扑环境Varnish:192.168.31.250Web01:192.168.31.83Web02:192.168.31.141配置 web01、web02 做为后端服务器（过程略）确保 varnish 服务器能正常访问 web01、web02Varnish 缓存代理服务器配置：

安装 varnish
1、安装依赖关系的软件包（注：使用 centos 在线 yum 源）

[root@varnish ~]# yum -y install autoconf automake libedit-devel libtool ncurses-devel pcre-devel   pkgconfig python-docutils python-sphinx

2、安装 varnish
Varnish 的官方网址为 http://varnish-cache.org，可以在这里下载最新版本的软件。
下载地址：https://www.varnish-cache.org/content/varnish-cache-403
注意：Varnish 网站有时会被墙。
Git 下载：git clone https://github.com/varnish/Varnish-Cache /var/tmp/
解压，进入解压目录编译安装：

[root@varnish ~]# tar zxf varnish-4.0.3.tar.gz[root@varnish ~]# cd varnish-4.0.3/[root@varnish varnish-4.0.3]# export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig

注：
./autogen.sh
如果从 Git 库下载的安装包时才需要运行，用于生成 configure 编译文件。
配置：

[root@varnish varnish-4.0.3]# ./configure

注：不指定安装路径，默认是安装在/usr/local 目录下
编译、安装

[root@varnish varnish-4.0.3]# make && make install

复制 vcl 文件（在编译安装目录下），如果安装目录里没有 default.vcl 文件。
复制到安装目录的/usr/local/var/varnish/目录下（当然并无必需要求在哪个目录，因为正式
启动时还得指定这个文件的目录）
[root@varnish varnish-4.0.3]# cp etc/example.vcl /usr/local/var/varnish/default.vcl

配置default.vcl

[root@varnish varnish-4.0.3]#  vim /usr/loacl/var/varnish/default.vclvcl 4.0;import directors;import std;probe backend_healthcheck {    .url="/";    .interval = 5s;    .timeout = 1s;    .window = 5;    .threshold = 3;}backend web_app_01 {    .host = "192.168.164.10";   #要改    .port = "80";    .first_byte_timeout = 9s;    .connect_timeout = 3s;    .between_bytes_timeout = 1s;    .probe = backend_healthcheck;}backend web_app_02 {    .host = "192.168.164.20";  #要改    .port = "80";    .first_byte_timeout = 9s;    .connect_timeout = 3s;    .between_bytes_timeout = 1s;    .probe = backend_healthcheck;} acl purgers {    "127.0.0.1";    "localhost";    "192.168.164.0/24";           #添加网段} sub vcl_init {    new web = directors.round_robin();    web.add_backend(web_app_01);    web.add_backend(web_app_02);} sub vcl_recv {set req.backend_hint = web.backend();if (req.method == "PURGE") {    if (!client.ip ~ purgers) {    return (synth(405, "Not Allowed."));}return (purge);}if (req.method != "GET" &&req.method != "HEAD" &&req.method != "PUT" &&req.method != "POST" &&req.method != "TRACE" &&req.method != "OPTIONS" &&req.method != "PATCH" &&req.method != "DELETE") {return (pipe);}if (req.method != "GET" && req.method != "HEAD") {return (pass);} if (req.url ~ "\.(php|asp|aspx|jsp|do|ashx|shtml)($|\?)") {return (pass);}if (req.http.Authorization) {return (pass);}if (req.http.Accept-Encoding) {if (req.url ~"\.(bmp|png|gif|jpg|jpeg|ico|gz|tgz|bz2|tbz|zip|rar|mp3|mp4|ogg|swf|flv)$") {unset req.http.Accept-Encoding;} elseif (req.http.Accept-Encoding ~ "gzip") {set req.http.Accept-Encoding = "gzip";} elseif (req.http.Accept-Encoding ~ "deflate") {set req.http.Accept-Encoding = "deflate";} else {unset req.http.Accept-Encoding;}}if (req.url ~"\.(css|js|html|htm|bmp|png|gif|jpg|jpeg|ico|gz|tgz|bz2|tbz|zip|rar|mp3|mp4|ogg|swf|flv)($|\?)") {unset req.http.cookie;return (hash);}if (req.restarts == 0) {if (req.http.X-Forwarded-For) {set req.http.X-Forwarded-For = req.http.X-Forwarded-For + ", " + client.ip;} else {set req.http.X-Forwarded-For = client.ip;}}return (hash);}sub vcl_hash {hash_data(req.url);if (req.http.host) {hash_data(req.http.host);} else {hash_data(server.ip);}return (lookup);}sub vcl_hit {    if (req.method == "PURGE") {    return (synth(200, "Purged."));    }    return (deliver);}sub vcl_miss {if (req.method == "PURGE") {return (synth(404, "Purged."));}return (fetch);}sub vcl_deliver {if (obj.hits > 0) {set resp.http.X-Cache = "HIT";set resp.http.X-Cache-Hits = obj.hits;} else {set resp.http.X-Cache = "MISS";} unset resp.http.X-Powered-By;unset resp.http.Server;unset resp.http.X-Drupal-Cache;unset resp.http.Via;unset resp.http.Link;unset resp.http.X-Varnish;set resp.http.xx_restarts_count = req.restarts;set resp.http.xx_Age = resp.http.Age;set resp.http.hit_count = obj.hits;unset resp.http.Age;return (deliver);}sub vcl_pass {return (fetch);} sub vcl_backend_response {set beresp.grace = 5m;if (beresp.status == 499 || beresp.status == 404 || beresp.status == 502) {set beresp.uncacheable = true;} if (bereq.url ~ "\.(php|jsp)(\?|$)") {set beresp.uncacheable = true;} else { if (bereq.url ~ "\.(css|js|html|htm|bmp|png|gif|jpg|jpeg|ico)($|\?)") {set beresp.ttl = 15m;unset beresp.http.Set-Cookie;} elseif (bereq.url ~ "\.(gz|tgz|bz2|tbz|zip|rar|mp3|mp4|ogg|swf|flv)($|\?)") {set beresp.ttl = 30m;unset beresp.http.Set-Cookie;} else {set beresp.ttl = 10m;unset beresp.http.Set-Cookie;}}return (deliver);}sub vcl_purge {return (synth(200,"success"));}sub vcl_backend_error {if (beresp.status == 500 ||beresp.status == 501 ||beresp.status == 502 ||beresp.status == 503 ||beresp.status == 504) {return (retry);}}sub vcl_fini {return (ok); }

**启动 varnish**[root@varnish ~]# /usr/local/sbin/varnishd -f /usr/local/var/varnish/default.vcl -smalloc,200M -a 0.0.0.0:80[root@varnish ~]# netstat -anpt | grep 80