01 May 2022

Multiple ways to select pods using labels in Kubernetes

  • k8s
  • kubernetes
  • howto

Show all the labels of the running pods

You can use the following command to see the labels of the running pods.

kubectl get po --show-labels

You will see the following output, showing all the pods and their labels.

NAME             READY   STATUS    RESTARTS   AGE     LABELS
blue-backend     1/1     Running   0          2m59s   color=blue,tier=backend
green-frontend   1/1     Running   0          2m59s   color=green,tier=frontend
red-backend      1/1     Running   0          2m59s   color=red,tier=backend
red-frontend     1/1     Running   0          2m59s   color=red,tier=frontend

Get the pods with specific labels and display them as columns

Just like in the previous example, you can use the following command - notice flag -L and pass the labels which you want to see as columns.

kubectl get pods -L color,tier

You will see in the output that label color and tier are displayed as columns.

NAME             READY   STATUS    RESTARTS   AGE    COLOR   TIER
blue-backend     1/1     Running   0          3m7s   blue    backend
green-frontend   1/1     Running   0          3m7s   green   frontend
red-backend      1/1     Running   0          3m7s   red     backend
red-frontend     1/1     Running   0          3m7s   red     frontend

Get the pods without a specific label

Equally easily, you can get all the pods without a specific label.

kubectl get pods -L color,tier -l '!color'

Because there are no pods without color label, you will see the following output.

No resources found in default namespace.

Get the pods where label has a specific value

In this example, we are looking for running pods with label color with value red.

kubectl get pods -L color,tier -l 'color=red'

You will see that only pods with color=red are displayed.

NAME           READY   STATUS    RESTARTS   AGE     COLOR   TIER
red-backend    1/1     Running   0          4m32s   red     backend
red-frontend   1/1     Running   0          4m32s   red     frontend

Get the pods where the value of label is one of the specified values

Here, we are looking for running pods with label color with value blue or green. The command is

kubectl get pods -L color,tier -l 'color in (blue,green)'

You will see that only pods with color=blue or color=green are displayed.

NAME             READY   STATUS    RESTARTS   AGE   COLOR   TIER
blue-backend     1/1     Running   0          5m    blue    backend
green-frontend   1/1     Running   0          5m    green   frontend