Nginx模块之SessionSticky

0 工作原理

Session Sticky 模块在upstream 返回响应后，向客户的浏览器写入 Cookie ，默认名为route ，保存的内容是一个 md5 码。

之后，模块接收到客户浏览器的请求时，就根据 route 来决定将请求转发到 upstream中哪台服务器上。

这是源码包中附带的流程图，将模块的处理流程描述的非常清晰：

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1 下载 Session
Sticky

wget https://nginx-sticky-module.googlecode.com/files/nginx-sticky-module-1.1.tar.gz

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2 安装模块

如果 Nginx 之前已经安装了，可以通过 nginx
-V 命令查看当时编译的参数。在参数后面追加安装 Session Sticky 模块的参数，

避免影响之前 Nginx 已有模块。

进入 nginx 源码目录，执行命令：

./configure …  --add-module=/usr/local/src/nginx-sticky-module-1.1

         make

         make install

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3 激活模块

在 upstream块中添加 sticky; 即可激活Session
Sticky模块。

upstream {

  sticky;

  server 127.0.0.1:9000;

  server 127.0.0.1:9001;

  server 127.0.0.1:9002;

}

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4 可用选项

The "sticky" command can take several arguments to control its behaviour:

  sticky [name=route] [domain=.foo.bar] [path=/] [expires=1h] [hash=index|md5|sha1] [no_fallback];

Configuration	Description	Parameters	Default Value
name	the name of the cookie used to track the persistant upstream srv	can be any string	"route"
domain	the domain in which the cookie will be valid	can be any string	nothing. Let the browser handle this.
path	the path in which the cookie will      be valid	can be any path	nothing. Let the browser handle this.
expires	the validity duration of the cookie	must be a duration greater than one second	nothing. It's a session cookie
hash	the hash mechanism to encode upstream server. It cant' be used      with hmac	md5|sha1	md5
hmac	The HMAC hash mechanism to encode upstream server. It's like      the hash mechanism but it uses hmac_key to secure the hashing.      It can't be used with hash.	md5|sha1	none
hmac_key	The key to use with hmac. It's mandatory when hmac is set.	can be any string	none
no_fallback	When this flag is set, nginx will return a 502 (Bad Gateway orProxy Error) if a request comes      with a cookie and the corresponding backend is unavailable.	no arguments	none

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参考资料

1 使用nginx
sticky 模块实现基于 cookie 的负载均衡

http://my.oschina.net/766/blog/156693

2 官方网站

https://code.google.com/p/nginx-sticky-module/wiki/Documentation