nginx的URI匹配规则

yinl_li

　　关于nginx的URI匹配规则，nginx的官方文档中有这么一句话：

写道

If there are several matching location blocks nginx selects the one with the longest prefix.
　　也就是说，如果nginx的配置文件有多个location指令，那么匹配请求URI前缀最长的那个location指令将负责处理该请求。
　　下面举个真实的例子来帮助大家对该规则有更直观的理解。
　　此例中有以下location指令：

    location / {
root   /var/www;
index  index.html index.htm;
}
location /cgit {
include fastcgi_params;
fastcgi_param SCRIPT_FILENAME /var/www/cgit/cgit.cgi;
fastcgi_param PATH_INFO $uri;
fastcgi_pass 127.0.0.1:8999;
}
location = /404.html {
root   /usr/share/nginx/html;
}

　　那么对于请求/cgit-css/cgit.css，它不会被 location /指令截获，而被location /cgit截获，因为该指令能够配最长的URI前缀。以下是nginx的关于URI和location指令匹配的debug日志：

2014/04/09 16:26:35 [debug] 4876#0: *57 http request line: "GET /cgit-css/cgit.css HTTP/1.1"
2014/04/09 16:26:35 [debug] 4876#0: *57 http uri: "/cgit-css/cgit.css"
2014/04/09 16:26:35 [debug] 4876#0: *57 http args: ""
2014/04/09 16:26:35 [debug] 4876#0: *57 http exten: "css"
2014/04/09 16:26:35 [debug] 4876#0: *57 http process request header line
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "Host: vmcentos64"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "Accept-Encoding: gzip, deflate"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "Connection: keep-alive"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "Accept: text/css,*/*;q=0.1"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "If-Modified-Since: Wed, 09 Apr 2014 14:25:02 GMT"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_1) AppleWebKit/537.73.11 (KHTML, like Gecko) Version/7.0.1 Safari/537.73.11"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "Accept-Language: zh-cn"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "Referer: http://vmcentos64/cgit/"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header: "Cache-Control: max-age=0"
2014/04/09 16:26:35 [debug] 4876#0: *57 http header done
2014/04/09 16:26:35 [debug] 4876#0: *57 event timer del: 3: 1189284449
2014/04/09 16:26:35 [debug] 4876#0: *57 generic phase: 0
2014/04/09 16:26:35 [debug] 4876#0: *57 rewrite phase: 1
2014/04/09 16:26:35 [debug] 4876#0: *57 http script regex: "^/$"
2014/04/09 16:26:35 [notice] 4876#0: *57 "^/$" does not match "/cgit-css/cgit.css", client: 192.168.56.1, server: _, request: "GET /cgit-css/cgit.css HTTP/1.1", host: "vmcentos64", referrer: "http://vmcentos64/cgit/"
2014/04/09 16:26:35 [debug] 4876#0: *57 test location: "/"
2014/04/09 16:26:35 [debug] 4876#0: *57 test location: "50x.html"
2014/04/09 16:26:35 [debug] 4876#0: *57 test location: "cgit"
2014/04/09 16:26:35 [debug] 4876#0: *57 using configuration "/cgit"

　　以上日志开始部分说明了HTTP请求的URI，中间是HTTP头信息，最后一行说明了那个location指令匹配了。由此可见，上述nginx配置会导致对css文件的请求转发到CGI程序上去了，这显然是不正确的。这种错误的配置的根源是对nginx的location匹配规则没有真正的理解。