Label

Kubernetes Official Docs - Labels and Selectors

In Kubernetes, labels are a system to organize objects into groups. Labels are key-value pairs that are attached to each object. Label selectors can be passed along with a request to the apiserver to retrieve a list of objects which match that label selector.

To add a label to a pod, add a labels section under metadata in the pod definition:

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: nginx
...

To label a running pod

kubectl label pod mynginx type=webserver
# pod "mynginx" labeled

To list pods based on labels

kubectl get pods -l type=webserver

NAME      READY     STATUS    RESTARTS   AGE
mynginx   1/1       Running   0          21m