What is an annotation in Kubernetes?

In Kubernetes, an annotation is a key-value pair that is used to attach arbitrary non-identifying metadata to objects. Annotations can be used to store information that is not meant to be used for identification or selection, such as build information, contact details, or other descriptive data.

Annotations are similar to labels, but while labels are intended for grouping and selecting objects, annotations are meant for storing additional information that may be useful for tools and libraries interacting with the Kubernetes API.

You can add annotations to various Kubernetes objects, such as Pods, Services, and Deployments, using the kubectl annotate command. For example:

kubectl annotate pod my-pod my-annotation-key=my-annotation-value

This command adds an annotation with the key my-annotation-key and the value my-annotation-value to the Pod named my-pod.