简述：Varnish是一款高性能的开源HTTP加速器，挪威最大的在线报纸 Verdens Gang 使用3台Varnish代替了原来的12台Squid，性能比以前更好。
系统环境：
CentOS release 5.5 (Final) 64-bit
所需软件：
varnish-2.1.4.tar.gz
Varnish官方网站：
http://www.varnish-cache.org/
安装前准备：
创建apache用户和组，以及Varnish缓存文件存放目录（/var/vcache）：
/usr/sbin/groupadd apache -g 48
/usr/sbin/useradd -u 48 -g apache apache
mkdir -p /var/vcache
chmod +w /var/vcache
chown -R apache:apache /var/vcache
创建Varnish日志目录（/var/logs/）：
mkdir -p /var/logschmod +w /var/logs
chown -R apache:apache /var/logs
安装：
wget http://repo.varnish-cache.org/source/varnish-2.1.4.tar.gztar zxvf varnish-2.1.4.tar.gz
cd varnish-2.1.4
./configure -prefix=/usr/local/varnish
make
make install
cd ..
配置：
默认配置文件样板：
/usr/local/varnish/etc/varnish/default.vcl
cd /usr/local/varnish/etc/varnish/
cp default.vcl elain_vcl.conf
vi elain_vcl.conf#############################
backend www {.host = “www.elain.org”;
.port = “80”;
}
sub vcl_recv {
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;
}
}
if (req.request != “GET” &&
req.request != “HEAD” &&
req.request != “PUT” &&
req.request != “POST” &&
req.request != “TRACE” &&
req.request != “OPTIONS” &&
req.request != “DELETE”) {
/ Non-RFC2616 or CONNECT which is weird. /
return (pipe);
}
if (req.request != “GET” && req.request != “HEAD”) {
/ We only deal with GET and HEAD by default /
return (pass);
}
if (req.http.Authorization || req.http.Cookie) {
/ Not cacheable by default /
return (pass);
}
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 (!obj.cacheable) {
return (pass);
}
return (deliver);
}
sub vcl_miss {
return (fetch);
}
sub vcl_fetch {
if (!beresp.cacheable) {
return (pass);
}
if (beresp.http.Set-Cookie) {
return (pass);
}
return (deliver);
}
sub vcl_deliver {
return (deliver);
}
sub vcl_error {
set obj.http.Content-Type = “text/html; charset=utf-8”;
synthetic {“
<?xml version=”1.0” encoding=”utf-8”?>
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
“} obj.status “ “ obj.response {“ Error “} obj.status “ “ obj.response {“
“} obj.response {“
Guru Meditation:
XID: “} req.xid {“
Varnish cache server
“};
return (deliver);
}
###################################
配置文件解释：
(1)、Varnish通过反向代理请求后端IP为1.0.0.121，端口为80的web服务器；
(2)、Varnish允许localhost、127.0.0.1、10.0.0.*三个来源IP通过PURGE方法清除缓存；
(3)、Varnish对域名为www.elain.org的请求进行处理，非www.elain.org域名的请求则返回“elain Cache Server”；
(4)、Varnish对HTTP协议中的GET、HEAD请求进行缓存，对POST请求透过，让其直接访问后端Web服务器。之所以这样配置，是因为POST请求一般是发送数据给服务器的，需要服务器接收、处理，所以不缓存；
(5)、Varnish对以.txt和.js结尾的URL缓存时间设置1小时，对其他的URL缓存时间设置为30天。
启动Varnish
ulimit -SHn 65535/usr/local/varnish/sbin/varnishd -f /usr/local/varnish/etc/varnish/elain_vcl.conf -a /var/vcache -s malloc,1G -u apache -g apache -T 127.0.0.1:2000 -a 0.0.0.0:8080
注：通常我们apache或nginx等 WEB 会使用8080端口，这样 我们就把上面的启动参数选项-a去掉，让其默认使用80端口（也就是在配置文件里的端口）
启动varnishncsa用来将Varnish访问日志写入日志文件：
/usr/local/varnish/bin/varnishncsa -n /var/vcache -w /var/logs/varnish.log &
停止Varnish
pkill varnish
配置开机自动启动Varnish
vi /etc/rc.local
在末尾增加以下内容：
ulimit -SHn 65535
/usr/local/varnish/sbin/varnishd -f /usr/local/varnish/etc/varnish/elain_vcl.conf -n /var/vcache -s malloc,1G -u apache -g apache -T 127.0.0.1:2000
/usr/local/varnish/bin/varnishncsa -n /var/vcache -w /var/logs/youvideo.log &
优化Linux内核参数
vi /etc/sysctl.conf
在末尾增加以下内容：
net.ipv4.tcp_fin_timeout = 30net.ipv4.tcp_keepalive_time = 300
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.ip_local_port_range = 5000 65000
sysctl -p
管理Varnish：
1、查看Varnish服务器连接数与命中率：
/usr/local/varnish/bin/varnishstat
2、通过Varnish管理端口进行管理：
用help看看可以使用哪些Varnish命令：
/usr/local/varnish/bin/varnishadm -T 127.0.0.1:2000 help
[root@postfix varnish]# /usr/local/varnish/bin/varnishadm -T 127.0.0.1:2000 help
help [command]
ping [timestamp]
auth response
quit
banner
status
start
stop
stats
vcl.load
vcl.inline
vcl.use
vcl.discard
vcl.list
vcl.show
param.show [-l] []
param.set
purge.url
purge
purge.list
3、通过Varnish管理端口，使用正则表达式批量清除缓存：
(1)、例：清除类似http://www.elain.org/tmp/aa.html的URL地址）：
/usr/local/varnish/bin/varnishadm -T 127.0.0.1:2000 url.purge /tmp/
(2)、例：清除类似http://www.elain.org/dl 的URL地址：
/usr/local/varnish/bin/varnishadm -T 127.0.0.1:2000 url.purge w*$
(3)、例：清除所有缓存：
/usr/local/varnish/bin/varnishadm -T 127.0.0.1:2000 url.purge *$
每天0点运行，按天切割Varnish日志，生成一个压缩文件，同时删除上个月旧日志的脚本（/var/logs/cutlog.sh）：
/var/logs/cutlog.sh文件内容如下：
#!/bin/sh
This script run at 00:00
date=$(date -d “yesterday” +”%Y-%m-%d”)
pkill -9 varnishncsa
mv /var/logs/youvideo.log /var/logs/${date}.log
/usr/local/varnish/bin/varnishncsa -n /var/vcache -w /var/logs/youvideo.log &
mkdir -p /var/logs/youvideo/
gzip -c /var/logs/${date}.log > /var/logs/youvideo/${date}.log.gz
rm -f /var/logs/${date}.log
rm -f /var/logs/youvideo/$(date -d “-1 month” +”%Y-%m*”).log.gz
设置在每天00:00定时执行：
crontab -e
0 0 * /bin/sh /var/logs/cutlog.sh
配置实例：
#Example 1 - manipulating headers
#Lets say we want to remove the cookie for all objects in the /static directory of our web server::
sub vcl_recv {
if (req.url ~ “^/images”) {
unset req.http.cookie;
}
}
Now, when the request is handled to the backend server there will be no cookie header. The interesting line is the one with the if-statement. It matches the URL, taken from the request object, and matches it against the regular expression. Note the match operator. If it matches the Cookie: header of the request is unset (deleted).
#Example 2 - manipulating beresp
#Here we override the TTL of a object comming from the backend if it matches certain criteria::
sub vcl_fetch {
if (beresp.url ~ “.(png|gif|jpg)$”) {
unset beresp.http.set-cookie;
set beresp.ttl = 3600;
}
}
#Example 3 - ACLs¶
#You create a named access control list with the acl keyword. You can match the IP address of the client against an ACL with the match operator.:
Who is allowed to purge….
acl local {
“localhost”;
“10.0.0.0.0”/24; / and everyone on the local network /
! “10.0.0.0.23”; / except for the dialin router /
}
sub vcl_recv {
if (req.request == “PURGE”) {
if (client.ip ~ local) {
return(lookup);
}
}
}
sub vcl_hit {
if (req.request == “PURGE”) {
set obj.ttl = 0s;
error 200 “Purged.”;
}
}
sub vcl_miss {
if (req.request == “PURGE”) {
error 404 “Not in cache.”;
}
}
补充几条相关命令
查看Varnish状态
/usr/local/varnish/bin/varnishstat -n /var/vcache/
查看访问最多的Referer
/usr/local/varnish/bin/varnishtop -n /var/vcache/ -i rxheader -I Referer
查看访问最多的URL
/usr/local/varnish/bin/varnishtop -n /var/vcache/ -i rxurl
官方文档：
http://www.varnish-cache.org/docs/2.1/
FAQ:
1、安装出错
configure: error: Package requirements (libpcre) were not met:
No package ‘libpcre’ found
答：yum install pcre-devel -y