varnish如何存储缓存对象：

file: 单个文件；不支持持久机制；

malloc: 缓存在内存中；

persistent：基于文件的持久存储；（此方式不建议使用）

vcl：配置缓存系统的缓存机制；【线程中缓存功能的工作机制】

一、在vs2和vs3上安装http

写入文件，内容一个为on vs2，另一个为on vs3

[root@vs2 ~]# yum install http
[root@vs2 ~]# for i in {1..10}; do echo "web$i on vs2" > /var/www/html/test$i.html; done
[root@vs2 ~]# ls /var/www/html/
test10.html  test2.html  test4.html  test6.html  test8.html
test1.html   test3.html  test5.html  test7.html  test9.html
[root@vs2 ~]# systemctl start httpd.service

二、安装varnish（在centos7上安装4.0.3版本）

[root@vs1 ~]# yum install varnish

三、varnish主程序的配置文件

[root@vs1 ~]# vim /etc/varnish/varnish.params # Varnish environment configuration description. This was derived from
# the old style sysconfig/defaults settings# Set this to 1 to make systemd reload try to switch vcl without restart.
RELOAD_VCL=1# Main configuration file. You probably want to change it.
VARNISH_VCL_CONF=/etc/varnish/default.vcl    #读取vcl配置文件的位置# Default address and port to bind to. Blank address means all IPv4
# and IPv6 interfaces, otherwise specify a host name, an IPv4 dotted
# quad, or an IPv6 address in brackets.
# VARNISH_LISTEN_ADDRESS=192.168.1.5
VARNISH_LISTEN_PORT=6081    #监听的服务端口为6081# Admin interface listen address and port
VARNISH_ADMIN_LISTEN_ADDRESS=127.0.0.1    #监听的管理地址为本机
VARNISH_ADMIN_LISTEN_PORT=6082    #监听的管理端口为6082# Shared secret file for admin interface
VARNISH_SECRET_FILE=/etc/varnish/secret    #密钥文件位置# Backend storage specification, see Storage Types in the varnishd(5)
# man page for details.
VARNISH_STORAGE="file,/var/lib/varnish/varnish_storage.bin,1G"    #缓存以文件的方式的存储位置和大小
#VARNISH_STORAGE="malooc,256M"    #以内存方式缓存，缓存大小为256M# Default TTL used when the backend does not specify one
VARNISH_TTL=120    #联系后端服务器超时时长# User and group for the varnishd worker processes
VARNISH_USER=varnish    #主进程所使用的用户
VARNISH_GROUP=varnish    #主进程所使用的组# Other options, see the man page varnishd(1)    #进程选项，线程池的最大值最小值和超时时长
DAEMON_OPTS="-p thread_pool_min=5 -p thread_pool_max=500 -p thread_pool_timeout=300"

四、varnish的命令行管理工具

[root@vs1 ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082
help
help [<command>]    #获取帮助信息
ping [<timestamp>]    #测试服务器是否正常
auth <response>    #
quit                #退出
banner
status            #显示服务器状态信息
start            #启动子进程
stop            #停止子进程
vcl.load <configname> <filename>    #载入哪个文件为配置文件
vcl.inline <configname> <quoted_VCLstring>
vcl.use <configname>                #使用哪个vcl文件
vcl.discard <configname>            #删除哪个vcl文件
vcl.list                     #列出所有可用的vcl文件
param.show [-l] [<param>]            #显示运行时参数
param.set <param> <value>
panic.show                     #显示恐慌信息，显示进程或子进程上次挂掉的原因
panic.clear                                        #清除恐慌信息
storage.list                                        #显示缓存信息
vcl.show [-v] <configname>                        #显示vcl文件的详细信息，vcl编译前的样子
backend.list [<backend_expression>]                #显示后端服务器列表
backend.set_health <backend_expression> <state>    #手动上线下线后端服务器
ban <field> <operator> <arg> [&& <field> <oper> <arg>]...    #清理缓存中的缓存对象
ban.list                                             #显示定义的清理缓存规则

varnish的访问日志

[root@vs1 ~]# varnishlog
[root@vs1 ~]# varnishtop

varnish的统计信息

[root@vs1 ~]# varnishstat

五、vcl配置文件的说明

http://book.varnish-software.com/4.0/chapters/VCL_Basics.html

http://book.varnish-software.com/4.0/_p_w_picpaths/simplified_fsm.svg

vcl_recv    接收请求
cacheable    判断是否为可缓存对象
incache        判断hash后的结果是否存在
vcl_hash    可缓存对象hash计算
vcl_hit    缓存中命中
vcl_miss    缓存中未命中
vcl_fetch    获取后端内容
vcl_deliver    构建缓存发送
vcl_pipe        客户端请求的方法不是常见方法时，直接交给后端服务器处理
vcl_pass        不检查缓存直接从后端服务器取
vcl_error    varnish直接返回错误响应

六、vcl配置文件

[root@vs1 ~]# cp /etc/varnish/default.vcl /etc/varnish/test.vcl
[root@vs1 ~]# vim /etc/varnish/test.vcl
# This is an example VCL file for Varnish.
#
# It does not do anything by default, delegating control to the
# builtin VCL. The builtin VCL is called when there is no explicit
# return statement.
#
# See the VCL chapters in the Users Guide at https://www.varnish-cache.org/docs/
# and http://varnish-cache.org/trac/wiki/VCLExamples for more examples.# Marker to tell the VCL compiler that this VCL has been adapted to the
# new 4.0 format.
vcl 4.0;# Default backend definition. Set this to point to your content server.
backend vs2 {    #定义后端主机vs2.host = "172.16.24.102";.port = "80";.probe = {    #对后端主机的test1进行进行健康状态检测.url = "/test1.html";}
}
backend vs3 {.host = "172.16.24.104";.port = "80";.probe = {.url = "/test1.html";}
}
#import directors;    #加载directors模块，在负载均衡轮询时要用到
#sub vcl_init {        #轮询方式的负载均衡
#    new mycluster = directors.round_robin();
#    mycluster.add_backend(vs2);
#    mycluster.add_backend(vs3);
#}sub vcl_recv {# Happens before we check if we have this in cache already.## Typically you clean up the request here, removing cookies you don't need,# rewriting the request, etc.#url中开头带有login或者admin的直接从后端主机取结果不缓存if (req.url ~ "(?i)^/login" || req.url ~ "(?i)^/admin") {  return(pass);}#url以jpg,png,gif结尾的直接发给vs2，其他的都发给vs3if (req.url ~ "(?i)\.(jpg|png|gif)$") {set req.backend_hint = vs2;} else {set req.backend_hint = vs3;}#    set req.backend_hint = mycluster.backend();    #负载均衡集群#如果客户端请求为PRI返回405，如果请求的为非GET,HEAD,PUT,POST,TRACE,OPTIONS,DELETE都直接发给后端主机处理if (req.method == "PRI") {/* We do not support SPDY or HTTP/2.0 */return (synth(405));}if (req.method != "GET" &&req.method != "HEAD" &&req.method != "PUT" &&req.method != "POST" &&req.method != "TRACE" &&req.method != "OPTIONS" &&req.method != "DELETE") {/* Non-RFC2616 or CONNECT which is weird. */return (pipe);}if (req.method != "GET" && req.method != "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 (hash);
}sub vcl_backend_response {# Happens after we have read the response headers from the backend.## Here you clean the response headers, removing silly Set-Cookie headers# and other mistakes your backend does.
}sub vcl_deliver {# Happens when we have all the pieces we need, and are about to send the# response to the client.## You can do accounting or modifying the final object here.#如果缓存能命中就在返回值中插入HIT,未命中则插入MISSif (obj.hits>0) {set resp.http.X-Cache = "HIT";} else {set resp.http.X-Cache = "MISS";}
}[root@vs1 ~]# varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082
vcl.load test2 test.vcl
200
VCL compiled.
vcl.use test2
200
VCL 'test2' now active

七、测试

在vs2上上传一张dog.jpg，在vs3上不上传任何图片