Openresty/Lua returns default error page instead of custom

Question

I'm currently trying to setup a WAF/DDOS protection using this script: https://github.com/C0nw0nk/Nginx-Lua-Anti-DDoS/blob/master/lua/anti_ddos_challenge.lua

Everything is working pretty well except that openresty/nginx returns the default 500 error page instead of the custom error_page shown below if one of the WAF rules gets a hit. See "WAF_URI_Request_table" at the script above.

each time the request gets blocked by these WAF rules I also get the following entry at my log:

2020/07/27 09:20:29 [error] 150#150: *16 rewrite or internal redirection cycle while internally redirecting to "/403.html", client: 172.21.0.5, server: localhost, request: "GET /test.php HTTP/1.1", host: "localhost"

My nginx configuration looks like this (shortened):

...
http {
     upstream backend {
        server 127.0.0.1:8000 max_fails=3 fail_timeout=60s;
     }
...
 server {
        listen 80;
        access_by_lua_file ddos_challenge.lua;
        aio threads=default;
...
location @proxy_to_app {
            proxy_pass http://backend;
            aio threads;
            proxy_read_timeout     100s;
            proxy_connect_timeout  100s;
            proxy_http_version 1.1;
            proxy_redirect off;
            proxy_buffers 16 4k;
            proxy_buffer_size 2k;
            proxy_intercept_errors on;
            proxy_set_header Host $host;
            uwsgi_intercept_errors on;
            gzip on;
            gzip_min_length 1024;
            gzip_comp_level 3;
            gzip_vary on;
            gzip_disable msie6;
            gzip_proxied expired no-cache no-store private auth;
            gzip_types text/css text/javascript text/xml text/plain text/x-component application/javascript application/x-javascript application/json application/xml application/rss+xml application/atom+xml font/truetype font/opentype application/vnd.ms-fontobject image/svg+xml;
            }

location / {
            try_files $uri @proxy_to_app;
            }
...
error_page 412 414 416 444 495 496 497 500 501 502 504 507 /custom_error.html;
        location = /custom_error.html {
            root /app/templates/;
            internal;
        }

Have you tried to move the /custom_error.html location above the / one? — un.def

Unknown Unknown · Accepted Answer · 2020-07-27T11:10:14

Found the mistake, see:

https://groups.google.com/g/openresty-en/c/1XASYFeP61o?pli=1

I moved the access_by_lua line to the / location block, that's it.

Openresty/Lua returns default error page instead of custom

1 Answers