Registering Zuul on Eureka in Kubernetes cluster
If you look at the configuration for Zuul Service Discovery you can see that there is an option:
eureka.serviceUrl.default=http://${region}.${eureka.eurekaServer.domainName}:7001/${eureka.eurekaServer.context}
You would have to point that option to your eureka-server Kubernetes Service. Based on the DNS Kubernetes convention it would be something like this:
eureka-server-service.<k8s-namespace>.svc.cluster.local:<port-of-service-you-exposed>