使用正则配置Nginx时出现过多重定向问题求助

问题描述 #

单项目配置Swagger时Nginx运行正常：

location /project1/v2 {
      
  absolute_redirect off;
  alias             /project1/v2;
  expires           1d;

  location ~* \.(?:json|yml|yaml)$ {
    # SWAGGER_ROOT
    expires         -1;
    include         /etc/nginx/templates/cors.conf;
  }

  include         /etc/nginx/templates/cors.conf;
}

location /project1{
  set               $args $args&url=http://localhost/project1/v2/swagger.json;
  absolute_redirect off;
  alias             /usr/share/nginx/html/;
  expires           1d;
  include           /etc/nginx/templates/cors.conf;
}

但改用正则匹配多项目（project1、project2）时，出现循环重定向，URL会变成重复叠加index.html和url参数的异常情况：

http://localhost/project1/index.html/index.html/.../?&url=http://localhost/project1/v2/swagger.json&url=...

对应的多项目配置如下：

location ~ ^/(project1|project2)/v2 {
      
  absolute_redirect off;
  alias             /$1/v2;
  expires           1d;

  location ~* \.(?:json|yml|yaml)$ {
    # SWAGGER_ROOT
    expires         -1;
    include         /etc/nginx/templates/cors.conf;
  }

  include         /etc/nginx/templates/cors.conf;
}

location ~ ^/(project1|project2) {
  set               $args $args&url=http://localhost/$1/v2/swagger.json;
  absolute_redirect off;
  alias             /usr/share/nginx/html/;
  expires           1d;
  include           /etc/nginx/templates/cors.conf;
}

错误原因 #

1. 正则匹配范围重叠：第二个正则~ ^/(project1|project2)会匹配所有以project1/project2开头的请求，包括已经被第一个/v2 location处理的请求，导致请求被重复拦截处理。
2. index自动重定向循环：访问/project1时，Nginx会自动查找index.html并发起重定向到/project1/index.html，而这个URL又会被第二个正则location匹配，再次执行set $args添加url参数；同时alias到静态目录后，又会触发index查找逻辑，陷入循环，最终导致路径和参数不断重复叠加。

修正后的配置 #

需要明确区分两个location的匹配优先级，同时避免index重定向循环，以下是两种可行的修正方案：

方案一：分路径精确匹配 #

# 优先匹配/v2路径，用^~提升优先级，避免被后续正则匹配
location ^~ /project1/v2 {
  absolute_redirect off;
  alias             /project1/v2;
  expires           1d;

  location ~* \.(?:json|yml|yaml)$ {
    expires         -1;
    include         /etc/nginx/templates/cors.conf;
  }

  include         /etc/nginx/templates/cors.conf;
}

location ^~ /project2/v2 {
  absolute_redirect off;
  alias             /project2/v2;
  expires           1d;

  location ~* \.(?:json|yml|yaml)$ {
    expires         -1;
    include         /etc/nginx/templates/cors.conf;
  }

  include         /etc/nginx/templates/cors.conf;
}

# 仅匹配项目根路径（/project1或/project2），直接指定index避免重定向
location ~ ^/(project1|project2)$ {
  set               $args $args&url=http://localhost/$1/v2/swagger.json;
  absolute_redirect off;
  alias             /usr/share/nginx/html/;
  index             index.html;
  expires           1d;
  include           /etc/nginx/templates/cors.conf;
}

# 匹配项目下的静态资源，排除/v2路径
location ~ ^/(project1|project2)/(?!v2) {
  absolute_redirect off;
  alias             /usr/share/nginx/html/;
  expires           1d;
  include           /etc/nginx/templates/cors.conf;
}

方案二：正则统一处理 #

# 优先匹配/v2路径，正则加^~提升优先级
location ~ ^/(project1|project2)/v2 {
  absolute_redirect off;
  alias             /$1/v2;
  expires           1d;

  location ~* \.(?:json|yml|yaml)$ {
    expires         -1;
    include         /etc/nginx/templates/cors.conf;
  }

  include         /etc/nginx/templates/cors.conf;
}

# 仅匹配项目根路径（/project1或/project2）
location ~ ^/(project1|project2)$ {
  set               $args $args&url=http://localhost/$1/v2/swagger.json;
  absolute_redirect off;
  alias             /usr/share/nginx/html/;
  index             index.html;
  expires           1d;
  include           /etc/nginx/templates/cors.conf;
}

# 匹配项目下的静态资源，排除/v2路径并正确映射文件
location ~ ^/(project1|project2)/(?!v2)(.*)$ {
  absolute_redirect off;
  alias             /usr/share/nginx/html/$2;
  expires           1d;
  include           /etc/nginx/templates/cors.conf;
}

内容的提问来源于stack exchange，提问作者Hasan Can Saral