nginx does not resolve upstream - nginx

Question

I have two AP server, and I want to setup NGINX as a proxy server and load balancer.
here is my nginx.conf file:
#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;
large_client_header_buffers 8 1024k;
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 /var/log/nginx/access.log main;
sendfile on;
#tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 650;
send_timeout 2000;
proxy_connect_timeout 2000;
proxy_send_timeout 2000;
proxy_read_timeout 2000;
gzip on;
#
# Load config files from the /etc/nginx/conf.d directory
# The default server is in conf.d/default.conf
map $http_upgrade $connection_upgrade {
default Upgrade;
'' close;
}
upstream backend {
server apserver1:8443;
server apserver2:8443;
}
server {
listen 8445 default ssl;
server_name localhost;
client_max_body_size 500M;
client_body_buffer_size 128k;
underscores_in_headers on;
ssl on;
ssl_certificate ./crt/server.crt;
ssl_certificate_key ./crt/server.key;
location / {
proxy_pass https://backend;
break;
}
}
}
apserver1 and apserver2 are my AP server and in fact they are IP address.
when I visit the nginx via https://my.nginx.server:8445, I can get the AP container's default page. In my case, it is the JETTY server default page. that means the NGINX works.
if anything going correctly, user accessing to https://my.nginx.server:8445/myapp will get the log in page. if user has logged in, my app will redirect the user to https://my.nginx.server:8445/myapp/defaultResource.
when I visit via https://my.nginx.server:8445/myapp as a NOT-logged-in user, I can get the log in page correctly.
when I visit via https://my.nginx.server:8445/myapp/defaultResource directly as a logged-in user, I can get the correct page.
but when I visit the url https://my.nginx.server:8445/myapp as a logged-in user, (if correctly, the URL should be redirect to https://my.nginx.server:8445/myapp/defaultResource), but the nginx translate the URL to https://backend/myapp/defaultResource, and Chrome give me the following error:
The server at backend can't be found, because the DNS lookup failed....(omited)
nginx, seems not resolve the upstream backend. what's wrong with my configuration?
AND if I use http instead of https, everything goes well.
any help is appreciated.

Answer 1

Try to add the "resolver" directive to your configuration:
http://nginx.org/r/resolver