Nginx 解决前端 CORS 跨域问题

问题描述

Access to XMLHttpRequest at 'http://localhost:8080/test' from origin 'http://localhost:63342' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource

前端Ajax或Axios等XMLHttpRequest请求一个第三方的接口时，会出现跨域问题。

解决方案

只需在Nginx侧过滤掉OPTIONS请求，不转发给第三方接口，直接在Nginx就返回前端。前端就会认为OPTIONS请求成功了继续发送POST请求，此时Nginx将此次的POST请求真正转发给第三方接口。

配置文件

location /test {
    if ($request_method = OPTIONS) {
        add_header Access-Control-Allow-Origin $http_origin; # 必须要有
        add_header Access-Control-Allow-Headers *; # 必须要有
        #add_header Access-Control-Allow-Methods GET,POST,OPTIONS; # 不加也行
        #add_header Access-Control-Allow-Credentials true; # 不加也行
        return 200; # 204也可以，只要返回成功码即可
    }
    proxy_pass  http://abc.com/def;
}
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