This page describes the CoreDNS upgrade process and how to install CoreDNS.
You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:
Your Kubernetes server must be at or later than version v1.9.To check the version, enter kubectl version.
CoreDNS is a flexible, extensible DNS server that is the default implementation of Kubernetes cluster DNS. Like Kubernetes, the CoreDNS project is hosted by the CNCF.
For manual deployment, see the documentation at the CoreDNS website.
You can check the version of CoreDNS that kubeadm installs for each version of Kubernetes in the page CoreDNS version in Kubernetes.
CoreDNS can be upgraded manually in case you want to only upgrade CoreDNS or use your own custom image. There is a helpful guideline and walkthrough available to ensure a smooth upgrade. Make sure the existing CoreDNS configuration ("Corefile") is retained when upgrading your cluster.
If you are upgrading your cluster using the kubeadm tool, kubeadm
can take care of retaining the existing CoreDNS configuration automatically.
When resource utilisation is a concern, it may be useful to tune the configuration of CoreDNS. For more details, check out the documentation on scaling CoreDNS.
You can configure CoreDNS to support many use cases beyond
basic service name resolution by modifying the CoreDNS configuration ("Corefile").
For more information, see the documentation
for the kubernetes CoreDNS plugin, or read the
Custom DNS Entries for Kubernetes.
in the CoreDNS blog.