As outlined in this issue, you may run into a problem where you want to log into the OpenShift cluster as system:admin from one of your master nodes but it keeps asking for credentials.
$ oc login -u system:admin Authentication required for https://localhost:8443 (openshift) Username: system:admin Password:
There are probably several solutions to tackle this. The one that worked for me is:
$ export KUBECONFIG=/etc/origin/master/admin.kubeconfig $ oc login -u system:admin