Linux平台部署varnish 高性能缓存服务器（2）

上一小节我们我们讲到关于varnish cache 编译安装，这里将围绕关于varnish讲解有关varnish的实例配置，即varnish主配置文件：default.vcl的配置
一.varnish的配置实例模板
一般我们将varnish的主配置文件default.vcl文件分为三大部分:后端webserver健康检查机制，后端webserver 主机配置区域，http请求url应用请求分发机制；
1.1 后端webserver健康检查机制模板样例配置
新建一个健康检查文件，并命名为health_check.vcl，并添加如下内容:

vim /usr/local/varnish/etc/health_check.vcl
内容如下:
probe healthcheck {
.url = "/";          #定义健康检查的页面
.interval = 6s;      #探测请求的发送周期，默认为5秒；
.timeout = 0.3 s;    #每次探测请求的过期时长
.window = 8;         #设定在判定后端主机健康状态时基于最近多少次的探测进行
.threshold = 3;      #在.window中指定的次数中，至少有多少次是成功的才判定后端主机正健康运行
.initial = 3;        #Varnish启动时对后端主机至少需要多少次的成功探测，默认同.threshold；
}

1.2 后端webserver主机池区域模板样例配置
新建一个健康检查文件，并命名为backends.vcl.vcl，并添加如下内容:

vim /usr/local/varnish/etc/backends.vcl.vcl
内容如下:
include "health_check.vcl";
#This is sale   webserver configure
backend web01 {                   #定义后端webserver的别名
.host = "10.0.11.145";        #定义后端webserver的IP地址
.port = "80";                 #定义后端webserver的web服务侦听端口

.first_byte_timeout = 9s;     #定义等待从backend传输过来的第一个字节的时间
.connect_timeout = 3s;        #定义等待连接后端的时间
.between_bytes_timeout = 1s;  #定义两个字节的间隔时间

.probe = healthcheck;         #定义两个字节的间隔时间
}

backend web02 {
.host = "10.0.11.146";
.port = "80";

.first_byte_timeout = 9s;
.connect_timeout = 3s;
.between_bytes_timeout = 1s;

.probe = backend_healthcheck;
}

import directors;                 #应用后端webserver负载机制
sub vcl_init {
new web = directors.random(); #设置负载均衡池的名字(这里为：web,即new后面值）以及负载均衡算法（即“directors的值”.round-robin“

web.add_backend(web01);       #在web负载池里添加后端web，即（）里的值
web.add_backend(web02);
}

注：varnish的调度算法有三种:
1.round-robin ：加权轮询，因为每个backend都有它的权重；
2.random      ：随机调度；
3.dns         ：基于DNS名称解析之后进行调度

1.2 后端webserver主机池区域模板样例配

vim /usr/local/varnish/etc/health_check.vcl
内容如下:
vcl 4.0;

import std;
include "backends.vcl";

acl allow_purge_cache {  #定义了允许哪些主机通过HTTP来执行PURG进行缓存删除策略
"127.0.0.1";
"10.0.0.0"/8;
"172.0.0.0"/8;
}

sub vcl_recv {
if (req.method == "PURGE") {
if (!client.ip ~ allow_purge_cache) {
return (synth(405, "Not Allowed."));
}

return (purge);
}

set req.backend_hint = web.backend(); #选择使用轮询的方式负载后端web-server

if (req.url ~ "\.(php|asp|aspx|jsp|do|ashx|shtml)($|\?)") {
return (pass);
}

#如果是请求为以上URL开头的请求（即动态请求）则直接转交到后端web处理，即进入到fetch（vcl_fetch）状态；

if (req.url ~ "\.(css|js|html|htm|bmp|png|gif|jpg|jpeg|ico|gz|tgz|bz2|tbz|zip|rar|mp3|mp4|ogg|swf|flv)($|\?)") {
unset req.http.cookie;
return (hash);
}

#如果是请求为以上类型的请求时，则会自动删除http头部的cookie信息，并且进入hash状态，会在hash表中查找数据，若找到，则进入 hit（vcl_hit）状态，否则进入 miss（vcl_miss）状态；

##首次访问增加X-Forwarded-For头信息,方便后端程序获取客户端IP信息
if (req.restarts == 0) {
#如果设置过此header则要再次附加上,用,隔开,如果只有一层代理的话,就无需设置了
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;  #没有则要加上
}
}

if (req.http.Cache-Control ~ "(?i)no-cache") {
if (!(req.http.Via || req.http.User-Agent ~ "(?i)bot" || req.http.X-Purge)) {
return (purge);
}
}

if (req.method != "GET" &&
req.method != "HEAD" &&
req.method != "PUT" &&
req.method != "POST" &&
req.method != "TRACE" &&
req.method != "OPTIONS" &&
req.method != "PATCH" &&
req.method != "DELETE") {
return (pipe);
}

#对于非正规的请求不进行缓存处理

if (req.method != "GET" && req.method != "HEAD") {
return (pass);
}

#对于不是“get”和“head”类型的请求直接转交给后端处理

if (req.http.Authorization) {
return (pass);
}
#对于http认证的页面也直接交给后端web处理

################定以支持压缩功能############################
if (req.http.Accept-Encoding) {
if (req.url ~ "\.(bmp|png|gif|jpg|jpeg|ico|gz|tgz|bz2|tbz|zip|rar|mp3|mp4|ogg|swf|flv)$") {
unset req.http.Accept-Encoding;
} elseif (req.http.Accept-Encoding ~ "gzip") {
set req.http.Accept-Encoding = "gzip";
} elseif (req.http.Accept-Encoding ~ "deflate") {
set req.http.Accept-Encoding = "deflate";
} else {
unset req.http.Accept-Encoding;
}
}

if (req.http.Upgrade ~ "(?i)websocket") {
return (pipe);
}

if (!std.healthy(req.backend_hint)) {
unset req.http.Cookie;
}

if (req.http.x-pipe && req.restarts > 0) {
unset req.http.x-pipe;
return (pipe);
}

return (hash);
}

sub vcl_pipe {
if (req.http.upgrade) {
set bereq.http.upgrade = req.http.upgrade;
}

return (pipe);
}

################定以vcl_pass函数段############################
sub vcl_pass {
if (req.method == "PURGE") {
return (synth(502, "PURGE on a passed object."));
}
}

################定以vcl_hash函数段############################
sub vcl_hash {
hash_data(req.url);

if (req.http.host) {
hash_data(req.http.host);
} else {
hash_data(server.ip);
}

if (req.http.Cookie) {
hash_data(req.http.Cookie);
}

if (req.http.Accept-Encoding ~ "gzip") {
hash_data("gzip");
} elseif (req.http.Accept-Encoding ~ "deflate") {
hash_data("deflate");
}
}

################定以vcl_hit函数段############################
sub vcl_hit {
if (req.method == "PURGE") {
return (synth(200, "Purged."));
}

if (obj.ttl >= 0s) {
return (deliver);
}

if (std.healthy(req.backend_hint)) {
if (obj.ttl + 10s > 0s) {
return (deliver);
} else {
return(fetch);
}
} else {
if (obj.ttl + obj.grace > 0s) {
return (deliver);
} else {
return (fetch);
}
}

return (deliver);
}

################定以vcl_miss函数段############################
sub vcl_miss {
if (req.method == "PURGE") {
return (synth(404, "Purged."));
}

return (fetch);
}

sub vcl_backend_response {
set beresp.grace = 5m;

set beresp.ttl = std.duration(regsub(beresp.http.Cache-Control, ".*s-maxage=([0-9]+).*", "\1") + "s", 0s);
if (beresp.ttl > 0s) {
unset beresp.http.Set-Cookie;
}

if (beresp.http.Set-Cookie) {
set beresp.uncacheable = true;
return (deliver);
}

if (beresp.http.Cache-Control && beresp.ttl > 0s) {
set beresp.grace = 1m;
unset beresp.http.Set-Cookie;
}

if (beresp.http.Content-Length ~ "[0-9]{8,}") {
set bereq.http.x-pipe = "1";
return (retry);
}

if (bereq.url ~ "\.(php|asp|aspx|jsp|do|ashx|shtml)($|\?)") {
set beresp.uncacheable = true;
return (deliver);
}

if (bereq.url ~ "\.(css|js|html|htm|bmp|png|gif|jpg|jpeg|ico|gz|tgz|bz2|tbz|zip|rar|mp3|mp4|ogg|swf|flv)($|\?)") {
unset beresp.http.set-cookie;
}

if (bereq.url ~ "^[^?]*\.(mp[34]|rar|tar|tgz|gz|wav|zip|bz2|xz|7z|avi|mov|ogm|mpe?g|mk[av])(\?.*)?$") {
unset beresp.http.set-cookie;
set beresp.do_stream = true;
set beresp.do_gzip = false;
}

if ((!beresp.http.Cache-Control && !beresp.http.Expires) ||
beresp.http.Pragma ~ "no-cache" ||
beresp.http.Cache-Control ~ "(no-cache|no-store|private)") {
set beresp.ttl = 120s;
set beresp.uncacheable = true;
return (deliver);
}

if (beresp.ttl <= 0s || beresp.http.Set-Cookie || beresp.http.Vary == "*") {
set beresp.ttl = 120s;
set beresp.uncacheable = true;
return (deliver);
}

if (bereq.url ~ "\.(css|js|html|htm|bmp|png|gif|jpg|jpeg|ico)($|\?)") {
set beresp.ttl = 15m;
} elseif (bereq.url ~ "\.(gz|tgz|bz2|tbz|zip|rar|mp3|mp4|ogg|swf|flv)($|\?)") {
set beresp.ttl = 30m;
} else {
set beresp.ttl = 10m;
}

return (deliver);
}

sub vcl_purge {
if (req.method != "PURGE") {
set req.http.X-Purge = "Yes";
return (restart);
}
}

sub vcl_deliver {
if (obj.hits > 0) {
set resp.http.X-Cache = "HIT from " + req.http.host;
set resp.http.X-Cache-Hits = obj.hits;
} else {
set resp.http.X-Cache = "MISS from " + req.http.host;
}

unset resp.http.X-Powered-By;
unset resp.http.Server;

unset resp.http.Via;
unset resp.http.X-Varnish;

unset resp.http.Age;
}

sub vcl_backend_error {
if (beresp.status == 500 ||
beresp.status == 501 ||
beresp.status == 502 ||
beresp.status == 503 ||
beresp.status == 504) {
return (retry);
}
}

sub vcl_fini {
return (ok);
}

以上即为varnish的三个相关配置模板示例，应用的时候，我们只需要根据应用需要，选取部分应用配置参考即可。

本文出自 “菜鸟的成长记” 博客，请务必保留此出处http://blief.blog.51cto.com/6170059/1732586