Kubernetes and Docker - An Enterprise Guide

Chapter 6: Services, Load Balancing, and External DNS

When you deploy an application to a Kubernetes cluster, your pods are assigned ephemeral IP addresses. Since the assigned addresses are likely to change as pods are restarted, you should never target a service using a pod IP address; instead, you should use a service object, which will map a service IP address to backend pods based on labels. If you need to offer service access to external requests, you can deploy an Ingress controller, which will expose your service to external traffic on a per-URL basis. For more advanced workloads, you can deploy a load balancer, which provides your service with an external IP address, allowing you to expose any IP-based service to external requests.