varnish高效缓存部署方式及原理详解

缓存：
命中率文档命中率字节命中率缓存类型：私有缓存公共缓存内容路由：ICP：互联网缓存协议HTCP:超文本缓存协议Cache Digest：Cache Pre-filling：CARP：缓存阵列路由协议缓存处理的具体步骤：接收请求解析请求（代理的功能）查询缓存（检查本地缓存中是否存在对方请求的内容的副本）副本的新鲜度检测（检查本地缓存的副本是否为最新版本）构建响应发送响应记录日志如何保证副本的新鲜度？1，内容过期机制：HTTP/1.0：Expires （过期时间）绝对时间HTTP/1.1：Cache-Control(max-age=)相对时长2，条件式请求：mtime（时间戳）：If-Modified-Since基于时间的条件式请求ETag(扩展标记): If-None-Match基于扩展标签条件式请求服务器或缓存服务器控制缓存的能力：由原始服务器定义：1，Cache-Control Max-age=s-max-age=no-store：不能缓存no-cache：能缓存，但不能直接使用次缓存对象，缓存对象在使用之前必须做新鲜度验证；must-revalidate：必须进行新鲜度验证PrivatePublic2，Expires：原始服务器不添加任何控制机制，而由缓存服务器自己决定缓存时长。 客户端控制是否使用缓存：Cache-Control：Max-stale：告知缓存机制可以使用国企的文档；no-cache：告知缓存机制必须进行验证，否则不会接受任何缓存文档；no-store：告知缓存机制必须尽快删除缓存中的文档HTTP/1.0Pragma：no-cache 能缓存必须进行新鲜度验证http协议：
Request：mrthod<url> versionHEADERS BODYResponse:Version status reasonHEADRES BODY首部：通用Connection：close|keep-aliveDate：日期时间Host：请求的主机Pragma： no-cacheVia：请求或响应在客户端和服务器之间传递时经过的代理Transfer-Encoding:消息主题的传输编码方式，chunked表示采用块编码的方式请求If-Modified-SinceIf-None-MatchRefererUser-Agent Host：请求的主机Accept-Encoding：接受的编码方式Accept-Language：接受的自然语言Accept-Charset：接受字符集Authorization：服务器端发送www-authenticate时，客户端通过此首部提供认证信息；响应ETag：内容的标签Location：重定向后的新位置Server：服务器软件信息WWW-Authenticate：要求对客户端进行认证Age：实体Content-EncodingContent-LanguageContent-LenthContent-Type：内容的MIME格式Expires：Last-Modified：最近一次的修改时间Varnish： 淘宝使用的是ATS（apace traffic server）
web缓存丶代理服务器：
Varnish 安装：
1,安装jemalloc
http://pkgs.org/download/libjemalloc.so.1()(64bit) 官网
下载地址
rpm -ivh http://dl.fedoraproject.org/pub/epel/6/x86_64/jemalloc-3.6.0-1.el6.x86_64.rpm 2,安装varnish
Varnish 3.0:
rpm --nosignature -i https://repo.varnish-cache.org/redhat/varnish-3.0.el6.rpm yum install varnish3,修改配置
使用文件缓存修改方法:
vim /etc/sysconfig/varnish/
VARNISH_STORAGE_FFILE=/var/lib/varnish/varnish_storage.bin
VARNISH_STORAGE="file,${VARNISH_STORAGE_FILE},${VARNISH_STORAGE_SIZE}"
使用内存缓存修改方法:
VARNISH_STORAGE="malloc,${VARNISH_STORAGE_SIZE}"
修改配置文件
varnish配置文件：
/etc/sysconfig/varnish

varnish控制语言：
/etc/varnish/default.vcl

一、修改varinsh监听端口：

vim /etc/sysconfig/varnish

VARNISH_LISTEN_PORT=80

二、复制控制语言配置文件

probe 后端服务器健康状况检查

interval = 1s； 一秒探测一次
window = 5； 最多打开五个窗口
threshold = 2； 若打开两个窗口探测都为正常，则此我们说此主机健康。否则抛弃。

director webs random(random是一种算法，分配方式随即) webs 是名字

purgers 清空缓存

acl purgers {
"127.0.0.1";
"192.168.100.0"/24;
}
允许谁来清空缓存
操作：
cp default.vcl /etc/varnish/defaul.vcl

vim /etc/varnish/default.val
修改host

修改purgers
acl purgers {
"127.0.0.1";
"192.168.100.0"/24;
}
修改域名：
sub vcl_recv {
if (req.http.host ~ "^www.bbs.com")
修改140行
添加html
if (req.request == "GET" && req.url ~ "\/[0-9]\.(htm|html)$")

service varnish restart

外放访问-------

使用varnishstat 查看命中率

curl -L http://www.bbs.com 查看是否命中
HIT为命中

default.vcl配置文件
# This is a basic VCL configuration file for varnish. See the vcl(7)
# man page for details on VCL syntax and semantics.
#
# Default backend definition. Set this to point to your content
# server.
#
backend web1 {
.host = "192.168.100.20";
.port = "80";
.probe = {
.url = "/";
.interval = 1s;
.window = 5;
.threshold = 2;
}
}

backend web2 {
.host = "192.168.100.30";
.port = "80";
.probe = {
.url = "/";
.interval = 1s;
.window = 5;
.threshold = 2;
}
}

director webs random {
.retries = 5;
{
.backend = web1;
.weight = 2;
}
{
.backend = web2;
.weight = 3;
}
}
acl purgers {
"127.0.0.1";
"192.168.0.0"/24;
}

#
# Below is a commented-out copy of the default VCL logic. If you
# redefine any of these subroutines, the built-in logic will be
# appended to your code.
sub vcl_recv {
if (req.http.host ~ "^www.bbs.com")
{ set req.backend = webs; }
else { error 404 "Unknown HostName!"; }
if (req.request == "PURGE") {
if (!client.ip ~ purgers) {
error 405 "Method not allowed";
}
return (lookup);
}
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.url ~ "\.(jpg|png|gif|swf|jpeg|ico)$")
{
unset req.http.cookie;
}
if (req.request == "GET" && req.url ~ "\.(php)($|\?)")
{ return (pass); }
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);
}
if (req.url ~ "^/fonts/")
{ return (pass); }
return (lookup);
}

sub vcl_pipe {
# # Note that only the first request to the backend will have
# # X-Forwarded-For set. If you use X-Forwarded-For and want to
# # have it set for all requests, make sure to have:
# # set bereq.http.connection = "close";
# # here. It is not set by default as it might break some broken web
# # applications, like IIS with NTLM authentication.
return (pipe);
}

sub vcl_pass {
return (pass);
}

sub vcl_hash {
hash_data(req.url);
if (req.http.host) {
hash_data(req.http.host);
} else {
hash_data(server.ip);
}
return (hash);
}

sub vcl_hit {
return (deliver);
}

sub vcl_miss {
return (fetch);
}

sub vcl_fetch {
if (beresp.ttl <= 0s ||
beresp.http.Set-Cookie ||
beresp.http.Vary == "*") {
/*
* Mark as "Hit-For-Pass" for the next 2 minutes
*/
set beresp.ttl = 120 s;
return (hit_for_pass);
}
if (req.request == "GET" && req.url ~ "\.(js|css|mp3|jpg|png|gif|swf|jpeg|ico)$")
{ set beresp.ttl = 7d; }
if (req.request == "GET" && req.url ~ "\/[0-9]\.(htm|html)$")
{ set beresp.ttl = 300s; }
return (deliver);
}

sub vcl_deliver {
set resp.http.x-hits = obj.hits ;
if (obj.hits > 0)
{ set resp.http.X-Cache = "HIT"; }
else { set resp.http.X-Cache = "MISS"; }
#return (deliver);
}

sub vcl_error {
set obj.http.Content-Type = "text/html; charset=utf-8";
set obj.http.Retry-After = "5";
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">
<html>
<head>
<title>"} + obj.status + " " + obj.response + {"</title>
</head>
<body>
<h1>Error "} + obj.status + " " + obj.response + {"</h1>
<p>"} + obj.response + {"</p>
<h3>Guru Meditation:</h3>
<p>XID: "} + req.xid + {"</p>
<hr>
<p>Varnish cache server</p>
</body>
</html>
"};
return (deliver);
}

sub vcl_init {
return (ok);
}

sub vcl_fini {
return (ok);
}

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