Because the application is in the internal network environment, it can not directly access the external network. However, the requirement is that the application needs to redirect to the external network environment's login QR code for code scanning and login. When processing page redirection, the client initiates the request. Therefore, the application cannot directly complete the operation, and needs to do forwarding processing. Here, nginx is used for forward proxy to realize the function.

nginx is configured as follows

#user nobody;
worker_processes 1;

#error_log logs/error.log;
#error_log logs/error.log notice;
#error_log logs/error.log info;

#pid logs/nginx.pid;


events {
    worker_connections 1024;
}


http {
    include mime.types;
    default_type application/octet-stream;

    #log_format main '$remote_addr - $remote_user [$time_local] "$request" '
    # '$status $body_bytes_sent "$http_referer" '
    # '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log logs/access.log main;

    sendfile on;
    #tcp_nopush on;

    #keepalive_timeout 0;
    keepalive_timeout 65;

    #gzip on;

    #server {
    # listen 80;
    # server_name localhost;
    #
    # #charset koi8-r;
    #
    # #access_log logs/host.access.log main;
    #
    # location / {
    # root html;
    # index index.html index.htm;
    # }
    #
    # #error_page 404 /404.html;
    #
    # # redirect server error pages to the static page /50x.html
    # #
    # error_page 500 502 503 504 /50x.html;
    # location = /50x.html {
    # root html;
    # }
    #
    # # proxy the PHP scripts to Apache listening on 127.0.0.1:80
    # #
    # #location ~ \.php$ {
    # # proxy_pass http://127.0.0.1;
    # #}
    #
    # # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    # #
    # #location ~ \.php$ {
    # # root html;
    # # fastcgi_pass 127.0.0.1:9000;
    # # fastcgi_index index.php;
    # # fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;
    # # include fastcgi_params;
    # #}
    #
    # # deny access to .htaccess files, if Apache's document root
    # # concurs with nginx's one
    # #
    # #location ~ /\.ht {
    # # deny all;
    # #}
    #}


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    #server {
    # listen 8000;
    # listen somename:8080;
    # server_name somename alias another.alias;

    # location / {
    # root html;
    # index index.html index.htm;
    # }
    #}


    # HTTPS server
    #
    #server {
    # listen 443 ssl;
    # server_name localhost;

    # ssl_certificate cert.pem;
    # ssl_certificate_key cert.key;

    # ssl_session_cache shared:SSL:1m;
    # ssl_session_timeout 5m;

    # ssl_ciphers HIGH:!aNULL:!MD5;
    # ssl_prefer_server_ciphers on;

    # location / {
    # root html;
    # index index.html index.htm;
    # }
    #}
    
    #HTTP
    server{
        resolver 8.8.8.8;
        #access_log /data/logs/nginx/access_proxy.log main;
        listen 80;
        location / {
            root html;
            index index.html index.htm;
            proxy_pass $scheme://$host$request_uri;
            proxy_set_header HOST $http_host;
            proxy_buffers 256 4k;
            proxy_max_temp_file_size 0k; 
            proxy_connect_timeout 30;
            proxy_send_timeout 60;
            proxy_read_timeout 60;
            proxy_next_upstream error timeout invalid_header http_502;
        }
        error_page 500 502 503 504 /50x.html;
        location = /50x.html {
            root html;
        }
    }

    #HTTPS
    server{
        resolver 8.8.8.8;
        #access_log /data/logs/nginx/access_proxy.log main;
        listen 443;
        location / {
            #proxy_pass https://$host$request_uri;
            proxy_pass https://xxxx.cn;
            proxy_buffers 256 4k;
            proxy_max_temp_file_size 0k; 
            proxy_connect_timeout 30;
            proxy_send_timeout 60;
            proxy_read_timeout 60;
            proxy_next_upstream error timeout invalid_header http_502;
        }
    }  
}