How Pods access Kubernetes DNS in Docker EE, part one

Service discovery is one of the important benefits of using a container/Pod orchestrator. When you create a Service in Kubernetes, controllers running behind the scenes create an entry in Kubernetes DNS records. Then other applications deployed in the cluster can look up the Service using its name. Kubernetes also configures routing within the cluster to send traffic for the Service to the Service’s ephemeral endpoint Pods.

Understanding Kubernetes DNS configuration and related traffic flow will help you troubleshoot problems accessing the cluster’s DNS from Pods. This is part one of a two-part deep-dive into how Kubernetes does this under the hood. In part one of this blog, we will look at how Kubernetes sets up DNS resolution for containers in Pods. In part two, we will look at how network traffic flows from containers in Pods for user workloads to the Pods providing DNS functionality. We’re going to use Kubernetes running under Docker Enterprise Edition for our examples in this blog.