If I stop the iptables service, things will work. I need to know how to change the iptables configuration to allow container access to host ports.
I have an nginx container on this RHEL 7 server accepting connections to port 443. On the same server, the jupyterhub is running on port 8000 without ssl. proxy_pass is used to open the jupyterhub from web browsers.
curl https://HOSTNAME <html> <head><title>502 Bad Gateway</title></head> docker logs nginx-container CLIENT-IP - - [08/Apr/2019:17:05:47 -0500] "GET / HTTP/1.1" 502 150 "-" "curl/7.29.0" "-" 2019/04/08 17:05:47 [error] 6#6: *11 connect() failed (113: No route to host) while connecting to upstream, client: CLIENT-IP, server: HOSTNAME, request: "GET / HTTP/1.1", upstream: "http://HOST-IP:8000/", host: "HOSTNAME"
If I use non-docker nginx proxy, there is no problem at all.