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:192.168.31.250
Web01:192.168.31.83
Web02:192.168.31.141
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、web02
Varnish 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）

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[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.vcl

vcl 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 -s
malloc,200M -a 0.0.0.0:80
[root@varnish ~]# netstat -anpt | grep 80