id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
1926	resolver should not cache failures	Orgad Shaneh		"If a domain is not found, the ""valid"" parameter is still effective, so if it becomes available again, nginx fails to resolve it until the cache timeout is reached.

This is likely to happen with docker-compose. Each container is accessed by its name using DNS resolution. If one of the containers is down and nginx looks it up, it will fail and will keep failing even if the container is brought up.

If I change the resolver to 127.0.0.11 valid=5s then it works as expected."	defect	closed	major		nginx-core	1.17.x	invalid	resolver		Linux e989be129352 5.3.0-24-generic #26-Ubuntu SMP Thu Nov 14 01:33:18 UTC 2019 x86_64 Linux	"nginx version: nginx/1.17.5
built by gcc 8.3.0 (Alpine 8.3.0)
built with OpenSSL 1.1.1c  28 May 2019 (running with OpenSSL 1.1.1d  10 Sep 2019)
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --with-perl_modules_path=/usr/lib/perl5/vendor_perl --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-Os -fomit-frame-pointer' --with-ld-opt=-Wl,--as-needed
"