id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
2274	Serving stale content, when proxy_cache_background_update is on and Cache-Control disappears	karol-gro@…		"''nginx for Windows''

I set up nginx proxy with following config


{{{
worker_processes  1;

events {
    worker_connections  1024;
}


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

    keepalive_timeout  65;
	
	proxy_cache_path C:\\folder\\cache levels=1:2 keys_zone=my_cache:1m max_size=1g inactive=12h use_temp_path=off;

    server {
        listen       4080;
        listen       [::]:4080;
        server_name  localhost;

        location /api/ {
            proxy_pass https://example.com;
            proxy_http_version 1.1;
            proxy_set_header X-TenantKey SomeKey;
        }

        location / {
            rewrite ""^/([^/]*/){3}(.*)$"" /$2 last ;

            proxy_pass https://SOMEACCOUNT.blob.core.windows.net/app/;
            proxy_http_version 1.1;

            proxy_cache my_cache;
            proxy_cache_use_stale error timeout updating http_500 http_502 http_503 http_504;
            proxy_cache_lock on;
            proxy_cache_background_update on;
        }
    }
}

}}}

Reproduction steps:
1. Create index.html file on blob storage with ''Test-1'' content and Cache-Control: max-age=30
2. Open IP:4080/a/b/c/index.html in HTTP client. It should work
3. Change content to ''Test-2'', keeping the Cache-Control. After some 30s you can see new content served by nginx
4. Change content to ''Test-3'' and remove Cache-Control header.

Expected result:
As all responses without cache-control, it will be treated as not-cachable. Background updater removes it from cache and nginx will proxy to source on each request

Actual result:
Nginx serves still an old ''Test-2'' with cache-control, even after 2 minutes. "	defect	closed	minor		nginx-module	1.19.x	duplicate	proxy, cache	karol-gro@…	Windows 10 Pro, 21H1, build 19043.1288	"nginx version: nginx/1.21.3
built by cl 16.00.40219.01 for 80x86
built with OpenSSL 1.1.1l  24 Aug 2021
TLS SNI support enabled
configure arguments: --with-cc=cl --builddir=objs.msvc8 --with-debug --prefix= --conf-path=conf/nginx.conf --pid-path=logs/nginx.pid --http-log-path=logs/access.log --error-log-path=logs/error.log --sbin-path=nginx.exe --http-client-body-temp-path=temp/client_body_temp --http-proxy-temp-path=temp/proxy_temp --http-fastcgi-temp-path=temp/fastcgi_temp --http-scgi-temp-path=temp/scgi_temp --http-uwsgi-temp-path=temp/uwsgi_temp --with-cc-opt=-DFD_SETSIZE=1024 --with-pcre=objs.msvc8/lib/pcre-8.44 --with-zlib=objs.msvc8/lib/zlib-1.2.11 --with-http_v2_module --with-http_realip_module --with-http_addition_module --with-http_sub_module --with-http_dav_module --with-http_stub_status_module --with-http_flv_module --with-http_mp4_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_auth_request_module --with-http_random_index_module --with-http_secure_link_module --with-http_slice_module --with-mail --with-stream --with-openssl=objs.msvc8/lib/openssl-1.1.1l --with-openssl-opt='no-asm no-tests -D_WIN32_WINNT=0x0501' --with-http_ssl_module --with-mail_ssl_module --with-stream_ssl_module"