反向代理：缓存
http/1.1 RFC http/1.1《-----http/1.0 cache http协议： request: method url version HEADERS
BODY
response:
version status reason
HEADERS
BODY
首部：
通用
Connection:close|keep-alive
Date：日期时间
Host：请求的主机
Pragma：no-cahce
Via：请求或响应在客户端和服务器之间传递时所经过的代理
Transfer-Encoding：消息主体的传输编码方式，chunked表示采用块编码的方式
请求
If-Modified-Since
If-None-Match
Referer
User-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
Accep-Charset:接受字符集
Authorization:服务端发送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
实体
Content-Encoding
Content-Language
Conten-Lenth
Content-Type:内容的MIME格式
Expires
Last-Modified
web object
browser：缓存机制 本地：
公共缓存（public） 私有缓存（private）
expire（过期时间）：2016-05-21 14:55:31 cache-control：max-age=600 etag（标识符）：一个时间随机生成数 last-mofified： if-modified-since： if-none-match： vary： age：
index.html：14:55:59
14:55:59,0000011：
条件式判断机制
CDN（content delivery network）：内容分发网络，一组缓存服务器组成的网络（集群）
www.maoshou.com in CNAME cache1.cdn.com www.maoshou.com in CNAME cache4.cdn.com
bind，view bind-dlz+MySQL pgsql，oracle，db4
Varnish: web缓存、代理服务器；
squid：varnish httpd：nginx
nginx+varnish nginx+squid
varnish配置要自己去编写配置文件：采用vcl编写工具
状态引擎：子例程，函数，可以使用return()函数返回状态给varnish进程 vcl_recv vcl_pass vcl_hash vcl_hit vcl_deliver vcl_miss vcl_fetch vcl_deliver 安装配置：
源始服务器：node2 varnish节点：node1（两块网卡）
node2: yum install php php-mysql mysql-server ifconfig eht0 192.168.20.12/24 up
vim /var/www/html/index.html node2.magedu.com service httpd restart
node1: ifconfig eth0 192.168.100.7/24 up ifconfig eth1 192.168.20.1/24 up yum install varnish rpm -ql varnish vim /etc/sysconfig/varnish VARNISH_LISTEN=80 VARNISH_STORAGE="malloc,100M"
service varnish start cd /etc/varnish vim test.vcl backend websrv1 { .host = "192.168.20.12"; .port = "80"; } 让自己写的配置文件生效： vim /etc/sysconfig/varnish VARNISH_VCL_CONF=/etc/varnish/test.vcl 或者varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082 help ping status stats vcl.list vcl.show boot vcl.load test1 /etc/varnish/test.vcl vcl.list vcl.use test1 vcl.show test1
http://172.16.100.7 curl -I http://192.168.100.7
vim test.vcl sub vcl_deliver { if (obj.hits > 0) { set resp.http.X-Cache = "HIT"; } else { set resp.http.X-Cache = "MISS"; } }
vcl.load test2 /etc/varnish/test.vcl vcl.use test2 vcl.show test2
curl -I http://172.16.100.7 crul -I http://172.16.100.7/index.html
node2: cd /var/www/html vim test.html test on node2.magedu.com
curl -I http://172.16.100.7/test.html
node1: vim test.vcl sub vcl_deliver { if (obj.hits > 0) { set resp.http.X-Cache = "HIT from "server.ip; } else { set resp.http.X-Cache = "MISS"; } }
vcl.load test3 /etc/varnish/test.vcl vcl.use test3 vcl.show test3
vcl -I http://172.16.100.7/test.html
vim test.vcl sub vcl_recv { if (req.url ~ "test.html") { return(pass); } return(lookup); }
vcl.load test4 /etc/varnish/test.vcl vcl.use test4
curl -I http://172.16.100.7/index.html curl -I http://172.16.100.7/test.html
vim test.vcl sub vcl_fetch { if (req.url ~ ".(jpg|jpeg|gif|png)$") { set beresp.ttl = 7200s; } if (req.url ~ ".(html|css|js)$") set beresp.ttl = 1200s; } }
vcl.load test5 /etc/varnish/test.vcl vcl.use test5 curl -I http://172.16.100.7/index.html
删除缓存： vim test.vcl acl purgers { "127.0.0.1"; "172.16.0.0"/16; } sub vcl_recv { if (req.request == "PURGE") { if (!client.ip ~ purgers) { error 405 "Method not allowed"; } } if (req.url ~ "test.html") { return(pass); } return(lookup); } sub vcl_hit { if (req.request == "PURGE") { purge; error 200 "purged ok"; } } sub vcl_miss { if (req.request == "PURGE") { purge; error 404 "not in cache"; } } sub vcl_pass { if (req.request == "PURGE") { error 502 "purged on a passed object"; } }
vcl.load test6 /etc/varnish/test.vcl vcl.use test6 curl -I http://172.16.100.7/index.html curl -X PURGE http://172.16.100.7/index.html
多台后端主机的健康状况检查:（node2和node3） ifconfig eth0 192.168.20.13/24 up
node1: vim test.vcl backend web1 { .host = "192.168.20.12"; .port = "80"; } director wesrvs random { { .backend = web1; .weight = 2; } { .backend = { .host = "192.168.20.13"; .port = "80"; } weight = 1; } } 或者： backend web1 { .host = "192.168.20.12"; .port = "80"; .probe = { (让该节点离线) .url = "/index.html"; .window = 5; .threshold = 2; .interval = 3s; } } backend web2 { .host = "192.168.20.13"; .port = "80"; } director websrvs random { { .backend = web1; .weight = 2; } { .backend = web2; .weight = 1; } } sub vcl_recv { set req.backend = websrvs; if (req.request == "PURGE") { if (!client.ip ~ purgers) { error 405 "Method not allowed"; } } if (req.url ~ "test.html") { return(pass); } return(lookup); }
vcl.load test7 test.vcl vcl.use test7 curl http://172.16.100.7/index.html
请求不同内容时，转发至不同主机： vim test.vcl 把director那一栏全部注释 sub vcl_recv { if (req.url ~ ".(html|css|js)$") { set req.backend = web1; } else { set req.backend = web2; } if (req.request == "PURGE") { if (!client.ip ~ purgers) { error 405 "Method not allowed"; } } if (req.url ~ "test.html") { return(pass); } return(lookup); }
vcl.load test8 test.vcl vcl.use test8
