id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
2315	set environment in nginx configuration does not work	duttab49@…		"Hello,

We have production deployment in AWS EKS where traffic from public Load balancer is routed to internal load balancer using nginx - using proxy_pass.
However, due to nginx caching of old load balancer IP addresses, nginx forward traffic to an IP address which does not exists as load balancer IP address is changed. 
To address this issue, we have used following approach in nginx configuration  - https://www.nginx.com/blog/dns-service-discovery-nginx-plus/#:~:text=resolver%2010.0.0.2%20valid%3D10s%3B%0A%0Aserver%20%7B%0A%20%20%20%20location%20/%20%7B%0A%20%20%20%20%20%20%20%20set%20%24backend_servers%20backends.example.com%3B%0A%20%20%20%20%20%20%20%20proxy_pass%20http%3A//%24backend_servers%3A8080%3B%0A%20%20%20%20%7D%0A%7D

resolver 10.0.0.2 valid=10s;

server {
    location / {
        set $backend_servers backends.example.com;
        proxy_pass http://$backend_servers:8080;
    }
}

But the above solution did not work. With set $env, nginx returns 404 error.

Please suggest. 
We are seeing performance issue with Nginx caching the Load balancer IP address in production deployment. This is with nginx 1.20 running in AWS EC2 instance. 
 "	defect	closed	blocker		documentation	1.19.x	invalid			Linux ip-xxx-xx-xxx-xx.AWS_REGION.compute.internal 4.14.252-195.483.amzn2.x86_64 #1 SMP Mon Nov 1 20:58:46 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux	"nginx version: nginx/1.20.0
built by gcc 7.3.1 20180712 (Red Hat 7.3.1-13) (GCC)
built with OpenSSL 1.1.1g FIPS 21 Apr 2020
TLS SNI support enabled
configure arguments: --prefix=/usr/share/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib64/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --http-client-body-temp-path=/var/lib/nginx/tmp/client_body --http-proxy-temp-path=/var/lib/nginx/tmp/proxy --http-fastcgi-temp-path=/var/lib/nginx/tmp/fastcgi --http-uwsgi-temp-path=/var/lib/nginx/tmp/uwsgi --http-scgi-temp-path=/var/lib/nginx/tmp/scgi --pid-path=/run/nginx.pid --lock-path=/run/lock/subsys/nginx --user=nginx --group=nginx --with-compat --with-debug --with-file-aio --with-google_perftools_module --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_degradation_module --with-http_flv_module --with-http_geoip_module=dynamic --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module=dynamic --with-http_mp4_module --with-http_perl_module=dynamic --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-http_xslt_module=dynamic --with-mail=dynamic --with-mail_ssl_module --with-pcre --with-pcre-jit --with-stream=dynamic --with-stream_ssl_module --with-stream_ssl_preread_module --with-threads --with-cc-opt='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic' --with-ld-opt='-Wl,-z,relro -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wl,-E'"