By default, the services/cray-externaldns-coredns-tcp and services/cray-externaldns-coredns-udp services both share the same Customer Access Network (CAN) external IP as defined by the can-external-dns value. This value is specified during the csi config init input.
It is expected to be in the static range reserved in MetalLB’s can-dynamic-pool subnet. Theoretically, this is the only CAN IP address that must be known external to the system so IT DNS can delegate the system-name.site-domain zone to services/cray-externaldns-coredns deployments.
Changing it after install is relatively straightforward, and only requires the external IP address for services/cray-externaldns-coredns-tcp and services/cray-externaldns-coredns-udp services to be changed. This procedure will update the IP addresses that DNS queries.
The system is installed.
Find the external IP address for the services/cray-externaldns-coredns-tcp and services/cray-externaldns-coredns-udp services.
ncn-w001# kubectl -n services get svc | grep cray-externaldns-coredns-
cray-externaldns-coredns-tcp LoadBalancer 10.25.211.48 10.102.14.113 53:31111/TCP 2d2h
cray-externaldns-coredns-udp LoadBalancer 10.25.156.88 10.102.14.113 53:32674/UDP 2d2h
Edit the services and change spec.loadBalancerIP to the desired CAN IP address.
Edit the cray-externaldns-coredns-tcp service.
ncn-w001# kubectl -n services edit svc cray-externaldns-coredns-tcp
Edit the cray-externaldns-coredns-udp service.
ncn-w001# kubectl -n services edit svc cray-externaldns-coredns-udp