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：
1 下载 Session Sticky
wget https://nginx-sticky-module.googlecode.com/files/nginx-sticky-module-1.1.tar.gz
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
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;
}
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
|
参考资料
1 使用nginx
sticky 模块实现基于 cookie 的负载均衡
2 官方网站