How to Format the Output of “kubectl” Command

By default, the output from the “kubectl” command will be easily readable by humans, But it can be further formatted based on our needs with the “-o” flag

kubectl [command] [TYPE] [NAME] -o 

Below are the commonly used format

• -o json
• -o name
• -o wide
• -o yaml
• Using JSONPath expressions

Using -o json format

-o json will provide a JSON formatted API object

Example:

Output with JSON format:

kubectl create namespace test-123 --dry-run -o json

{
    "kind": "Namespace",
    "apiVersion": "v1",
    "metadata": {
        "name": "test-123",
        "creationTimestamp": null
    },
    "spec": {},
    "status": {}
}

Using -o yaml format

-o yaml will provide a YAML formatted API Object

Output with YAML format:

kubectl create namespace test-123 --dry-run -o yaml

apiVersion: v1
kind: Namespace
metadata:
  creationTimestamp: null
  name: test-123
spec: {}
status: {}

Using -o wide format

-o wide helps us to get the output with more additional information.

It’s the most commonly used output format to get additional information about the resource

Example:

kubectl get pods -o wide

NAME      READY   STATUS    RESTARTS   AGE     IP          NODE     NOMINATED NODE   READINESS GATES
busybox   1/1     Running   0          3m39s   10.20.0.2   node01              
ningx     1/1     Running   0          7m32s   10.21.0.1   node02              
redis     1/1     Running   0          3m59s   10.22.0.1   node03              
master $

Using -o name format

-o name help to print the resource name and no other extra information

Example:

kubectl get pod -o name

pod/frontend-deployment_1
pod/frontend-deployment_2
pod/frontend-deployment_3
pod/frontend-deployment_4

Using JSONPath expressions

Kubectl uses a JSON path to filter out a particular topic from the resource definition file and provide it as an output. This expression is enclosed in the curly bracket {}

For example to get all the names from the running pods using the JSON path expression

YAML FILE:

apiVersion: v1
kind: Pod
metadata:
  labels:
    name: busybox-pod
    pod-template-hash: 6d8c45b946
  name: frontend-deployment_1
  namespace: default
  ownerReferences:
  - apiVersion: apps/v1
    controller: true
    kind: ReplicaSet
    name: frontend-deployment_1
spec:
  containers:
  - command:
    - sh
    - -c
    - echo Hello Kubernetes! && sleep 3600
    image: busybox888
    imagePullPolicy: Always
    name: busybox-container
    resources: {}
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-qnq5f
      readOnly: true
  restartPolicy: Always
  schedulerName: default-scheduler
  securityContext: {}
  serviceAccount: default
  serviceAccountName: default
  terminationGracePeriodSeconds: 30
  tolerations:
  - effect: NoExecute
    key: node.kubernetes.io/not-ready
    operator: Exists
    tolerationSeconds: 300
  - effect: NoExecute
    key: node.kubernetes.io/unreachable
    operator: Exists
    tolerationSeconds: 300
  volumes:
  - name: kube-api-access-qnq5f
    projected:
      defaultMode: 420

To get the pod name using JSON path expression

kubectl get pods -o=jsonpath='{.items[0].metadata.name}'

Output

frontend-deployment_1

To get the pod name from all running pods using JSON path expression

kubectl get pods -o=jsonpath='{.items[*].metadata.name}'

Output:

frontend-deployment_1 frontend-deployment_2 frontend-deployment_3 frontend-deployment_4

Good Luck with your Learning !!