Using URL instead of IP

[swati]

Hi,

I intend to use nginx as load balancer for routing traffic to an application
running on two separate Openshift (kubernetes) clusters.
The app urls are -> app.dc1.example.com and app.dc2.example.com.
When I curl to these individually I get required page.
However, it seems, nginx resolves it into IP instead of treating it as mere
destinations.
See below my config.

Since the apps are running on Openshift, they do not have a specific
(public) IP address.
Ping for app.dc1.example.com (and for that matter app.dc2.example.com) will
give the IP of the machine where DNS service is running for that Openshift
cluster.

Is there a way to configure nginx to route the requests to the URLs without
trying to resolve it into IP addresses?

Thanks
Swati

---
upstream lbtest { 
	server app.dc1.example.com ; 
	server app.dc2.example.com ; 
}

server {
    listen 9087;
    location / {
        proxy_set_header Host $host;
	proxy_pass http://lbtest;
    }
}
---

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,281790,281790#msg-281790