随着网站访问人数越来越多，承受的并发和压力也越来越高，这时候我们需要对网站和架构进行优化，今天我们来讨论使用Squid对架构进行优化，缓存网站。网上对squid描述的文章也有成千上万，我这里简单记录一下实践的步骤。
一、实施环境
- 系统版本：CentOSx86_64 5.8
- Squid版本：squid-2.6
- Nginx版本：nginx-1.4.2
二、正式安装
安装之前我们需要对系统进行优化，主要优化系统内核相关参数，仅供参考：
#sysctl.conf config 2014-03-26
net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
net.ipv4.tcp_max_tw_buckets = 10000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.netdev_max_backlog = 262144
net.core.somaxconn = 262144
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 1
net.ipv4.tcp_syn_retries = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
net.ipv4.tcp_keepalive_time = 15
net.ipv4.ip_local_port_range = 1024 65535
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接下来上自动安装Squid脚本，里面分别配置了两个虚拟主机域名，前端有LVS，LVS均衡后端多组squid集群，根据命中率去调整squid集群的数量，Squid后端均衡Nginx或者Apache。（完整的架构LVS+Keepalived+Squid+Nginx+Resin/Tomcat/PHP+MySQL集群）
简单逻辑图如下：
直接上脚本：
#!/bin/sh
#Auto make install squid server
#Author wugk 2014-03-26
SQUID_CNF=/etc/squid/squid.conf
CACHE_DIR=(
/data/cache1
/data/cache2
)
#Install squid shell
yum install -y squid
#config squid.conf
cat >>$SQUID_CNF <<EOF
#global config squid.conf 2014-03-26
http_port 80 accel vhost vport
cache_peer 192.168.149.128 parent 80 0 originserver name=wugk1
cache_peer 192.168.149.129 parent 80 0 originserver name=wugk2
cache_peer_domain wugk1 www.wugk1.com
cache_peer_domain wugk2 www.wugk2.com
visible_hostname localhost
forwarded_for off
via off
cache_vary on
#acl config
acl manager proto cache_object
acl localhost src 127.0.0.1/32
acl to_localhost dst 127.0.0.0/8 0.0.0.0/32
acl localnet src 10.0.0.0/8 # RFC1918 possible internal network
acl localnet src 172.16.0.0/12 # RFC1918 possible internal network
acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
acl SSL_ports port 443
acl Safe_ports port 80 8080 # http
acl Safe_ports port 21 # ftp
acl Safe_ports port 443 # https
acl all src 0.0.0.0/0
acl CONNECT method CONNECT
http_access allow manager localhost
http_access deny manager
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
http_access allow localnet
http_access allow localhost
http_access allow all
acl PURGE method PURGE
http_access allow PURGE localhost
http_access deny PURGE
#squid config 2014-03-25
cache_dir aufs /data/cache1 10240 16 256
cache_dir aufs /data/cache2 10240 16 256
cache_mem 4000 MB
maximum_object_size 8 MB
maximum_object_size_in_memory 256 KB
hierarchy_stoplist cgi-bin ?
coredump_dir /var/spool/squid
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
refresh_pattern \.(jpg|png|gif|mp3|xml|html|htm|css|js) 1440 50% 2880 ignore-reload
refresh_pattern . 0 20% 4320
EOF
#config cache_dir
mkdir -p ${CACHE_DIR[@]} ;chown -R squid:squid ${CACHE_DIR[@]}
#restart squid server
/etc/init.d/squid restart
if
[ "$?" == "0" ];then
echo "The Squid Server Install Successfully !!"
else
echo "The Squid Server Install Failed !!,Please Check Log......"
fi
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***测试，前端LVS截图（注LVS此处不配置了，博客有专门的安装方法）
通过浏览器查看head头，缓存命中情况截图如下：
通过命令
squidclient -p 80 mgr:info |egrep "(Request Hit Ratios|Byte Hit Ratios)"
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查看缓存命中率如下：
三、批量清空缓存
使用Shell脚本批量清空squid缓存脚本auto_clean_cache.sh
#!/bin/sh
DIR=/data/cache/
Command=/usr/sbin/squidclient
if
[ "$1" = "" ];then
echo "Usage:{$0 "\$1" ,Example exec $0 forum.php}"
exit
fi
grep -r -a $1 ${DIR} | strings | grep "http:"|grep -v "=" >list.txt
count=`cat list.txt|wc -l`
if
[ "$count" -eq "0" ];then
echo -e "---------------------------------\nThe $1 cache already update,Please exit ......"
exit
fi
while read line
do
$Command -m PURGE -p 80 "$line" >>/dev/null
if [ $? -eq 0 ];then
echo -e "----------------------------------\nThe $line cache update successfully!"
fi
done < list.txt
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脚本执行：
[root@node2 ~]# sh auto_clean_cache.sh forum.php
----------------------------------
The http://www.wugk2.com/forum.php cache update successfully!
[root@node2 ~]#
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更多squid优化及深入配置后期更新。
