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1.rewrite指令

rewrite指令可以定义在server块和location块中，用于URL重写。

rewrite指令的语法:

rewrite  regex 	replacement  [flag]

regex为正则表达式部分，用于匹配需要重写的url；replacement为替换内容，将匹配正则表达式的url替换为replacement; flag为可选项目，有4个枚举值:
[1] last : 本条规则匹配完成后，继续向下匹配新的location规则;
[2] break: 本条规则匹配完成即终止，不再匹配后面的任何规则;
[3] redirect : 返回302临时重定向，浏览器地址显示跳转后的URL地址；
[4] permanent : 返回301永久重定向，浏览器地址显示跳转后的URL地址;

2.使用案例

本章节中将通过案例介绍rewrite指令的用法以及4个flag值的作用和区别。

2.1 重写url地址

server {
    server_name localhost;
    listen 8001;

    rewrite ^/query/.*$   /ask/info;

    location /ask/info {
        return 200  "result from /ask/info";
    }
}

测试结果如下所示:

[root@124 html]# curl http://localhost:8001/query/info
result from /ask/info

其中: rewrite ^/query/.*$ /ask/info;表示将以/query/开头的url替换为/ask/info.
此时，可用正则表达式的分组对上述rewrite指令稍作修改:

rewrite ^/query/(.*)$   /ask/$1;

此时，表示将所有以/query/开头的url中的query替换为ask.

2.2 重定向：redirect 和permanent

server {
    server_name localhost;
    listen 8001;

    rewrite ^/query/.*$   /ask/info redirect;

    location /ask/info {
        return 200  "result from /ask/info";
    }
}

测试结果如下所示:

[root@124 ~]# curl -I http://localhost:8001/ask
HTTP/1.1 302 Moved Temporarily
Server: nginx/1.26.0
Date: Tue, 16 Jul 2024 11:37:41 GMT
Content-Type: text/html
Content-Length: 145
Location: http://localhost:8001/ask/info
Connection: keep-alive

修改为: rewrite ^/query/.*$ /ask/info permanent ;测试结果如下所示:

[root@124 ~]# curl -I http://localhost:8001/ask
HTTP/1.1 301 Moved Permanently
Server: nginx/1.26.0
Date: Tue, 16 Jul 2024 11:41:48 GMT
Content-Type: text/html
Content-Length: 169
Location: http://localhost:8001/ask/info
Connection: keep-alive

即redirect和permanent 的区别仅在于状态码，一个是302一个是301.

2.3 未添加flag:

server {
    server_name localhost;
    listen 8001;

    rewrite ^/ask(.*)$   /ask1/info;
    rewrite ^/ask(.*)$   /ask2/info;
    rewrite ^/ask(.*)$   /ask3/info;

    location /ask1/info {
        return 200  "result from /ask1/info";
    }

    location /ask2/info {
        return 200  "result from /ask2/info";
    }

    location /ask3/info {
        return 200  "result from /ask3/info";
    }
}

测试结果如下所示:

[root@124 html]# curl http://localhost:8001/ask
result from /ask3/info

测试结果表明3条rewrite依次被执行了，即未添加flage场景，rewrite指令不会发生中断。

2.4 last和break中断rewrite匹配

server {
    server_name localhost;
    listen 8001;

    rewrite ^/ask(.*)$   /ask1/info last;
    rewrite ^/ask(.*)$   /ask2/info;
    rewrite ^/ask(.*)$   /ask3/info;

    location /ask1/info {
        return 200  "result from /ask1/info";
    }

    location /ask2/info {
        return 200  "result from /ask2/info";
    }

    location /ask3/info {
        return 200  "result from /ask3/info";
    }
}

测试结果如下:

[root@124 install]# curl http://localhost:8001/ask
result from /ask1/info

将rewrite ^/ask(.*)$ /ask1/info last修改为 rewrite ^/ask(.*)$ /ask1/info break后，结果如下:

[root@124 logs]# curl http://localhost:8001/ask
result from /ask1/info

即last和break都会中断rewrite指令的继续执行。

2.5 last和break的区别

在location中使用rewrite时：last重写url后，会继续用重写后的值去匹配下面的location；而break重写url后，不会匹配location, 而是使用新的规则，直接发起一次http请求。

server {
	server_name localhost;
	listen 8001;


	location /break {
	  rewrite ^/break/(.*)$ /ask/$1 break;
	}

	location /last {
	  rewrite ^/last/(.*)$  /ask/$1 last;
	}

	location /ask {
	  return 200 "result from /ask";
	}
}

测试结果如下所示:

[root@124 logs]# curl http://localhost:8001/last/info
result from /ask


[root@124 logs]# curl http://localhost:8001/break/info
<html>
<head><title>404 Not Found</title></head>
<body>
<center><h1>404 Not Found</h1></center>
<hr><center>nginx/1.26.0</center>
</body>
</html>

对应404的error日志显示为:

#0: *54 open() "/usr/local/nginx/html/ask/info" failed (2: No such file or directory), client: 127.0.0.1, server: localhost, request: "GET /break/info HTTP/1.1", host: "localhost:8001"

结果表明，last重写后，会继续匹配location, 而break不再继续匹配location从而转向寻找文件，因找不到对应的/ask/info文件而抛出404.