1.介绍
http是现在服务中用的主流协议
restful
缓存 :
代理缓存-----proxy---类似于递归
旁挂式缓存-----类似于迭代
(递归:直接给出答案,不知道的被人去找答案)
(迭代:自己一级一级问)
缓存有过期机制和条件式请求
vanish具有代理式缓存
正向代理:代表客户端发请求 client
反向代理:代表服务器端 server
httpd既能做正向代理又能做反向代理
Nginx核心是代理,也可以缓存
squid : httpd
varnish : Nginx
Nginx用epoll做事件驱动
c10k:并发连接 connections 10k
c100k
vanish工作在客户端和服务器之间作反向代理,并且用作缓存
mysql关系型数据库
运维日常:
2.Web Page Cache:
squid --> varnish
程序的运行具有局部性特征:
时间局部性:一个数据被访问过之后,可能很快会被再次访问到
空间局部性:一个数据被访问时,其周边的数据也有可能被访问到
cache:命中
热区:局部性;(就像某宝推荐的商品有时效性和局部性)
时效性:
缓存空间耗尽:LRU,最近最少使用;
过期:缓存清理
缓存命中率:hit/(hit+miss) (命中次数/命中次数+未命中次数)
(0,1) 命中次数+为命中次数不一定等于总次数,有的不经过缓存访问
页面命中率:基于页面数量进行衡量
字节命中率: 基于页面的体积进行衡量
缓存与否:
私有数据:private,private cache;
公共数据:public,public or private cache;
Cache-related Headers Fields 缓存的区域性
The most important caching header fields are:
Expires:过期时间;
Expires:Thu, 22 Oct 2026 06:34:30 GMT
Cache-Control:max-age=
Etag
If-None-Match
Last-Modified
If-Modified-Since
Vary
Age
缓存有效性判断机制:
过期时间:Expires
HTTP\/1.0
Expires:过期
HTTP\/1.1
Cache-Control: maxage=
Cache-Control: s-maxage=
条件式请求:
Last-Modified/If-Modified-Since:基于文件的修改时间戳来判别;
Etag\/If-None-Match:基于文件的校验码来判别;
Expires:Thu, 13 Aug 2026 02:05:12 GMT
Cache-Control:max-age=315360000
ETag:"1ec5-502264e2ae4c0"
Last-Modified:Wed, 03 Sep 2014 10:00:27 GMT
缓存层级:
私有缓存:用户代理附带的本地缓存机制;
公共缓存:反向代理服务器的缓存功能;
User-Agent <--> private cache <--> public cache <--> public cache 2 <--> Original Server
请求报文用于通知缓存服务如何使用缓存响应请求:
(以下是请求报文可用的选项)
cache-request-directive =
"no-cache",
| "no-store"
| "max-age" "=" delta-seconds
| "max-stale" [ "=" delta-seconds ]
| "min-fresh" "=" delta-seconds
| "no-transform"
| "only-if-cached"
| cache-extension
响应报文用于通知缓存服务器如何存储上级服务器响应的内容:
(以下是响应报文可用的选项)
cache-response-directive =
"public"
| "private" [ "=" <"> 1#field-name <"> ]
| "no-cache" [ "=" <"> 1#field-name <"> ],可缓存,但响应给客户端之前 条件式请求进行缓存有效性验正;
| "no-store" ,不允许存储响应内容于缓存中;
| "no-transform"
| "must-revalidate"
| "proxy-revalidate"
| "max-age" "=" delta-seconds 定义最大缓存时长,过期时间
| "s-maxage" "=" delta-seconds 定义最大缓存时长,仅用于控制公共时长
| cache-extension
开源解决方案:
squid:
varnish:
varnish官方站点: http://www.varnish-cache.org/
Community
Enterprise
This is Varnish Cache, a high-performance HTTP accelerator.
varnish2.0,3.0处理过程
varnish4.0
varnish的程序环境:(我们只能缓存GET和HEAD请求)s
3.vanish程序架构:
vanish由manager和cacher进程组成,还有共享内存日志组件
Manager进程(主控进程)
Cacher进程,包含多种类型的线程:
accept, worker, expiry, ...
(cacher处理各种缓存事物,比如处理请求,管理缓存,清理过期缓存)
shared memory log:
( 共享内存日志:为了免得日志成为性能瓶颈,日志信息直接计入内存)
统计数据:计数器;
日志区域:日志记录;
varnishlog, varnishncsa, varnishstat...
配置接口:VCL
Varnish Configuration Language,
vcl complier --> c complier --> shared object
/etc/varnish/varnish.params:配置varnish服务进程的工作特性,例如监听的地址和端口,缓存机制;
/etc/varnish/default.vcl:配置各Child/Cache线程的缓存策略;
主程序:
/usr/sbin/varnishd
CLI interface:
/usr/bin/varnishadm
Shared Memory Log交互工具:
/usr/bin/varnishhist
/usr/bin/varnishlog
/usr/bin/varnishncsa
/usr/bin/varnishstat
/usr/bin/varnishtop
测试工具程序:
/usr/bin/varnishtest
VCL配置文件重载程序:
/usr/sbin/varnish_reload_vcl
Systemd Unit File:
/usr/lib/systemd/system/varnish.service
varnish服务
/usr/lib/systemd/system/varnishlog.service
/usr/lib/systemd/system/varnishncsa.service
日志持久的服务;
varnish的缓存存储机制( Storage Types):
-s [name=]type[,options]
· malloc[,size]
内存存储,[,size]用于定义空间大小;重启后所有缓存项失效;
· file[,path[,size[,granularity]]]
磁盘文件存储,黑盒;重启后所有缓存项失效;
· persistent,path,size
文件存储,黑盒;重启后所有缓存项有效;实验;暂不能用
varnish程序的选项:
程序选项:/etc/varnish/varnish.params文件
-a address[:port][,address[:port][...],默认为6081端口;
-T address[:port],默认为6082端口;
-s [name=]type[,options],定义缓存存储机制;
-u user
-g group
-f config:VCL配置文件;
-F:运行于前台;
...
运行时参数:/etc/varnish/varnish.params文件, DEAMON_OPTS
DAEMON_OPTS="-p thread_pool_min=5 -p thread_pool_max=500 -p thread_pool_timeout=300"
-p param=value:设定运行参数及其值; 可重复使用多次;
-r param[,param...]: 设定指定的参数为只读状态;
重载vcl配置文件:
~ ]# varnish_reload_vcl
# varnishadm(varnish客户端命令)
-S /etc/varnish/secret -T [ADDRESS:]PORT
help [<command>]
ping [<timestamp>]
auth <response>
quit
banner
status
start
stop
vcl.load <configname> <filename> 相当于varnish_relod_acl:加载ACL
vcl.inline <configname> <quoted_VCLstring>
vcl.use <configname>
vcl.discard <configname>
vcl.list
param.show [-l] [<param>]
param.set <param> <value>
panic.show
panic.clear
storage.list
vcl.show [-v] <configname>
backend.list [<backend_expression>]
backend.set_health <backend_expression> <state>
ban <field> <operator> <arg> [&& <field> <oper> <arg>]...
ban.list
配置文件相关:
vcl.list
vcl.load:装载,加载并编译;
vcl.use:激活;
vcl.discard:删除;
vcl.show [-v] <configname>:查看指定的配置文件的详细信息;
运行时参数:
param.show -l:显示列表;
param.show <PARAM>
param.set <PARAM> <VALUE>
缓存存储:
storage.list
后端服务器:
backend.list
VCL:
”域“专有类型的配置语言;
state engine:状态引擎;
VCL有多个状态引擎,状态之间存在相关性,但状态引擎彼此间互相隔离;每个状态引擎可使用return(x)指明关联至哪个下一级引擎;每个状态引擎对应于vcl文件中的一个配置段,即为subroutine
vcl_hash --> return(hit) --> vcl_hit
vcl_recv的默认配置:
sub vcl_recv {
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);
}
}
Client Side:
vcl_recv, vcl_pass, vcl_hit, vcl_miss, vcl_pipe, vcl_purge, vcl_synth, vcl_deliver
vcl_recv:
hash:vcl_hash
pass: vcl_pass
pipe: vcl_pipe
synth: vcl_synth
purge: vcl_hash --> vcl_purge
vcl_hash:
lookup:
hit: vcl_hit
miss: vcl_miss
pass, hit_for_pass: vcl_pass
purge: vcl_purge
Backend Side:
vcl_backend_fetch, vcl_backend_response, vcl_backend_error
两个特殊的引擎:
vcl_init:在处理任何请求之前要执行的vcl代码:主要用于初始化VMODs;
vcl_fini:所有的请求都已经结束,在vcl配置被丢弃时调用;主要用于清理VMODs;
vcl的语法格式:
(1) VCL files start with vcl 4.0;表明版本
(2) //, # and /* foo / for comments;//,#代表单行注释 / */代表多行注释
(3) Subroutines are declared with the sub keyword; 例如sub vcl_recv { ...};
每个子例程以sub关键字开头
(4) No loops, state-limited variables(受限于引擎的内建变量);不支持循环
(5) Terminating statements with a keyword for next action as argument of the return() function, i.e.: return(action);用于实现状态引擎转换;
(6) Domain-specific;
The VCL Finite State Machine
(1) Each request is processed separately;每个请求都是独立的
(2) Each request is independent from others at any given time;每个请求都与 其他的请求分离
(3) States are related, but isolated;状态是有关联的
(4) return(action); exits one state and instructs Varnish to proceed to the next state;return退出当前状态
(5) Built-in VCL code is always present and appended below your own VCL;
Built-in VCL 相当于默认vcl
三类主要语法:
sub subroutine {
...
}
if CONDITION {
...
} else {
...
}
return(), hash_data()
VCL Built-in Functions and Keywords
函数:
regsub(str, regex, sub)
regsuball(str, regex, sub)
ban(boolean expression)
hash_data(input)
synthetic(str)
Keywords:
call subroutine, return(action),new,set,unset
操作符:
==, !=, ~, >, >=, <, <=
逻辑操作符:&&, ||, !
变量赋值:=
举例:obj.hits是内建变量,用于保存某缓存项的从缓存中命中的次数;
if (obj.hits>0) {
set resp.http.X-Cache = "HIT via "(固定字符串) + server.ip;
} else {
set resp.http.X-Cache = "MISS from "(未能命中) + server.ip;
}
常用变量:
bereq., req.:
bereq.http.HEADERS
bereq.request:请求方法;
bereq.url:请求的url;
bereq.proto:请求的协议版本;
bereq.backend:指明要调用的后端主机;
req.http.Cookie:客户端的请求报文中Cookie首部的值;
req.http.User-Agent ~ "chrome"
beresp., resp.:
beresp.http.HEADERS
beresp.status:响应的状态码;
reresp.proto:协议版本;
beresp.backend.name:BE主机的主机名;
beresp.ttl:BE主机响应的内容的余下的可缓存时长;
obj.*
obj.hits:此对象从缓存中命中的次数;
obj.ttl:对象的ttl值,缓存过期
server.*
server.ip:varnish主机的IP;
server.hostname:varnish主机的Hostname
;
client.*
client.ip:发请求至varnish主机的客户端IP;
用户自定义:
set
unset
示例1:强制对某类资源的请求不检查缓存:
vcl_recv {
if (req.url ~ "(?i)^/(login|admin)") { (?i)表示忽略大小写,后面是匹配URI,
不包括主机名和端口
return(pass);
}
}
vcl.show test2 查看内容
vcl.use test2
示例2:对于特定类型的资源,例如公开的图片等,取消其私有标识,并强行设定其可以由varnish缓存的时长; 定义在vcl_backend_response中;
(并不是所有的cookie都不可以被缓存下来,可以剥离cookie)
if (beresp.http.cache-control !~ "s-maxage") {
if (bereq.url ~ "(?i).(jpg|jpeg|png|gif|css|js)$") {
unset beresp.http.Set-Cookie;
set beresp.ttl = 3600s;
}
}
示例3:定义在vcl_recv中;
if (req.restarts == 0) { 请求的重启次数为0
if (req.http.X-Fowarded-For) { 如果请求报文中有forwarded-for
set req.http.X-Forwarded-For = req.http.X-Forwarded-For + "," + client.ip;
} else {
set req.http.X-Forwarded-For = client.ip;
}
}
后端主机# vim /etc/httpd/conf/htttpd.conf
purge:手动修剪指定的缓存项
ban:一类的缓存项
(1) 能执行purge操作
sub vcl_purge {
return (synth(200,"Purged"));
}
(2) 何时执行purge操作
sub vcl_recv {
if (req.method == "PURGE") {
return(purge);
}
...
}
添加此类请求的访问控制法则:
acl purgers {
"127.0.0.0"/8;
"10.1.0.0"/16;
}
sub vcl_recv {
if (req.method == "PURGE") {
if (!client.ip ~ purgers) {
return(synth(405,"Purging not allowed for " + client.ip));
}
return(purge);
}
...
}
Banning:
(1) varnishadm:
ban <field> <operator> <arg>
示例:
ban req.url ~ ^/javascripts
(2) 在配置文件中定义,使用ban()函数;
示例:
if (req.method == "BAN") {
ban("req.http.host == " + req.http.host + " && req.url == " + req.url);
# Throw a synthetic page so the request won't go to the backend.
return(synth(200, "Ban added"));
}
ban req.http.host==www.ilinux.io && req.url==/test1.html
如何设定使用多个后端主机:
backend default {每添加一个后端主机就写一个backend,default代表一个主机名
.host = "172.16.100.6";真正主机的地址
.port = "80";真正主机的端口
}
backend appsrv {
.host = "172.16.100.7";
.port = "80";
}
sub vcl_recv {
if (req.url ~ "(?i).php$") {
set req.backend_hint = appsrv;
} else {
set req.backend_hint = default;
}
...
}
Director:
varnish module;
使用前需要导入:
import directors;
varnish两种调度算法轮询和随机
示例:
import directors; # load the directors
backend server1 {
.host =
.port =
}
backend server2 {
.host =
.port =
}
sub vcl_init {
new GROUP_NAME = directors.round_robin();
GROUP_NAME.add_backend(server1);
GROUP_NAME.add_backend(server2);
}
sub vcl_recv {
# send all traffic to the bar director:
set req.backend_hint = GROUP_NAME.backend();组名
}
会话保存的三种方式:
会话绑定 基于原IP绑定,基于应用层绑定
session复制
session服务器
基于cookie的session sticky:
sub vcl_init {
new h = directors.hash();
h.add_backend(one, 1); // backend 'one' with weight '1'
h.add_backend(two, 1); // backend 'two' with weight '1'
}
sub vcl_recv {
// pick a backend based on the cookie header of the client
set req.backend_hint = h.backend(req.http.cookie);
}
BE Health Check:
backend BE_NAME {
.host =
.port =
.probe = {
.url=
.timeout=
.interval=
.window=
.threshold=
}
}
.probe:定义健康状态检测方法;
.url:检测时要请求的URL,默认为”/";
.request:发出的具体请求;
.request =
"GET /.healthtest.html HTTP/1.1"
"Host: www.magedu.com"
"Connection: close"
.window:基于最近的多少次检查来判断其健康状态;
.threshold:最近.window中定义的这么次检查中至有.threshhold定义的次数是成功;
.interval:检测频度;每个多长时间检查一次
.timeout:超时时长;
.expected_response:期望的响应码,默认为200;
健康状态检测的配置方式:
(1) probe PB_NAME { }
backend NAME = {
.probe = PB_NAME;
...
}
(2) backend NAME {
.probe = {
...
}
}
示例:
probe check {
.url = "/.healthcheck.html";
.window = 5;
.threshold = 4;
.interval = 2s;
.timeout = 1s;
}
backend default {
.host = "10.1.0.68";
.port = "80";
.probe = check;
}
backend appsrv {
.host = "10.1.0.69";
.port = "80";
.probe = check;
}
手动设定BE主机的状态:
sick:管理down;
healthy:管理up;
auto:probe auto;
设置后端的主机属性:
backend BE_NAME {
...
.connect_timeout = 0.5s;
.first_byte_timeout = 20s;
.between_bytes_timeout = 5s;两个字节之间传送的间隔,如果超时也认为down
.max_connections = 50;
}
varnish的运行时参数:
线程模型:
cache-worker
cache-main
ban lurker
acceptor:
epoll/kqueue:
...
线程相关的参数:使用线程池机制管理线程;
在线程池内部,其每一个请求由一个线程来处理; 其worker线程的最大数决定了varnish的并发响应能力;
每个参数都要使用-p来引导
thread_pools:Number of worker thread pools. 最好小于或等于CPU核心数量;
thread_pool_max:每线程池的最大线程数;
thread_pool_min:The minimum number of worker threads in each pool. 额外意义为“最大空闲线程数”;
最大并发连接数 = thread_pools * thread_pool_max
thread_pool_timeout:Thread idle threshold. Threads in excess of thread_pool_min, which have been idle for at least this long, will be destroyed.
thread_pool_add_delay:Wait at least this long after creating a thread.添加线程延迟一段时间,使用默认值就好
thread_pool_destroy_delay:Wait this long after destroying a thread.
Timer相关的参数:
send_timeout:Send timeout for client connections. If the HTTP response hasn't been transmitted in this many seconds the session is closed.
timeout_idle:Idle timeout for client connections.
timeout_req: Max time to receive clients request headers, measured from first non-white-space character to double CRNL.
cli_timeout:Timeout for the childs replies to CLI requests from the mgt_param.
设置方式:
vcl.param
param.set
永久有效的方法:
varnish.params
DEAMON_OPTS="-p PARAM1=VALUE -p PARAM2=VALUE"
varnish运行时参数,重启缓存将失效
varnish日志区域:
shared memory log
计数器
日志信息
1、varnishstat - Varnish Cache statistics
-1 表示只显示一批就结束
-1 -f FILED_NAME
-f FILED_NAME 查看某一个字段
-l:可用于-f选项指定的字段名称列表;
MAIN.cache_hit
MAIN.cache_miss 没有命中
# varnishstat -1 -f MAIN.cache_hit -f MAIN.cache_miss
显示指定参数的当前统计数据;
# varnishstat -l -f MAIN -f MEMPOOL
列出指定配置段的每个参数的意义;
2、varnishtop - Varnish log entry ranking
-1 Instead of a continously updated display, print the statistics once and exit.
-i taglist,可以同时使用多个-i选项,也可以一个选项跟上多个标签;
-I <[taglist:]regex>
-x taglist:排除列表,出了什么其他的都显示
-X <[taglist:]regex>
3、varnishlog - Display Varnish logs
4、 varnishncsa - Display Varnish logs in Apache / NCSA combined log format
内建函数:
hash_data():
指明哈希计算的数据;减少差异,以提升命中率;
regsub(str,regex,sub):
把str中被regex第一次匹配到字符串替换为sub;主要用于URL Rewrite
regsuball(str,regex,sub):
把str中被regex每一次匹配到字符串均替换为sub;
return():
ban(expression)
ban_url(regex):
Bans所有的其URL可以被此处的regex匹配到的缓存对象;
synth(status,"STRING"):purge操作;
总结
varnish: state engine, vcl
varnish 4.0:
vcl_init
vcl_rec
vcl_hash
vcl_hit
vcl_pass
vcl_miss
vcl_pip
vcl_waiting
vcl_purge
vcl_deliver
vcl_synth
vcl_fini
vcl_backend_fetch
vcl_backend_response
vcl_backend_error
sub VCL_STATE_ENGINE {
...
}
backend BE_NAME {}
probe PB_NAME {}acl ACL_NAME {}
实战项目:两个lamp部署wordpress,用Nginx反代,做压测;nginx后部署varnish缓存,调整vcl,多次压测;
ab, http_load, webbench, seige, jmeter, loadrunner,...
补充资料:varnish book
http://book.varnish-software.com/4.0/
示例:
backend imgsrv1 {
.host = "192.168.10.11";
.port = "80";
}
backend imgsrv2
.host = "192.168.10.12";
.port = "80";
}
backend appsrv1 {
.host = "192.168.10.21";
.port = "80";
}
backend appsrv2 {
.host = "192.168.10.22";
.port = "80";
}
sub vcl_init {
new imgsrvs = directors.random();
imgsrvs.add_backend(imgsrv1,10);
imgsrvs.add_backend(imgsrv2,20);
new staticsrvs = directors.round_robin();
appsrvs.add_backend(appsrv1);
appsrvs.add_backend(appsrv2);
new appsrvs = directors.hash();
appsrvs.add_backend(appsrv1,1);
appsrvs.add_backend(appsrv2,1);
}
sub vcl_recv {
if (req.url ~ "(?i).(css|js)$" {
set req.backend_hint = staticsrvs.backend();
}
if (req.url ~ "(?i).(jpg|jpeg|png|gif)$" {
set req.backend_hint = imgsrvs.backend();
} else {
set req.backend_hint = appsrvs.backend(req.http.cookie);
}
}