NGINX in Openshift - NGINX can't resolve internal hostnames
Running ngnix in OpenShift 4.7 I was able to work around this issue by adding
resolver dns-default.openshift-dns.svc.cluster.local
to the server configuration. Apparently, ngnix is not parsing /etc/resolv.conf, but (in my case), dns-default.openshift-dns.svc.cluster.local also resolves to 172.30.0.10, which was defined as a nameserver in /etc/resolv.conf.
In Openshift cluster there is SkyDNS service on each master node. It normally listens on port 8053. Just use them as the resolver for nginx config and you will be fine:
resolver your-openshift-master-node1-ip:8053 your-openshift-master-node2-ip:8053;
From https://docs.openshift.com/container-platform/3.11/architecture/networking/networking.html#architecture-additional-concepts-openshift-dns, it looks like the following should work
<service>.<pod_namespace>.svc.cluster.local