Master Essential kubectl Commands for Efficient Kubernetes Management

kubectl Common Commands Guide

kubectl is the primary command‑line tool for interacting with a Kubernetes cluster; operators need to master its commands for efficient cluster management.

Kubectl Autocomplete

<code># setup autocomplete in bash (bash‑completion package required)
source <(kubectl completion bash)
# setup autocomplete in zsh
source <(kubectl completion zsh)</code>

Kubectl Context and Configuration

View merged kubeconfig, use multiple config files, query specific fields, switch contexts, and set credentials.

<code># Show merged kubeconfig
kubectl config view
# Use multiple kubeconfig files
KUBECONFIG=~/.kube/config:~/.kube/kubconfig2 kubectl config view
# Get password for user "e2e"
kubectl config view -o jsonpath='{.users[?(@.name == "e2e")].user.password}'
# Show current context
kubectl config current-context
# Set default context
kubectl config use-context my-cluster-name
# Add basic‑auth credentials
kubectl config set-credentials kubeuser/foo.kubernetes.com --username=kubeuser --password=kubepassword
# Set context with user and namespace
kubectl config set-context gce --user=cluster-admin --namespace=foo && kubectl config use-context gce</code>

Create Objects

Manifest files can be JSON or YAML (.yaml, .yml, .json). Use

kubectl create

with files, directories, URLs, or stdin.

<code># Create from a manifest file
kubectl create -f ./my-manifest.yaml
# Create from multiple files
kubectl create -f ./my1.yaml -f ./my2.yaml
# Create from all files in a directory
kubectl create -f ./dir
# Create from a URL
kubectl create -f https://git.io/vPieo
# Run an nginx pod
kubectl run nginx --image=nginx
# Explain resources
kubectl explain pods,svc
# Create multiple objects from stdin
cat <<EOF | kubectl create -f -
apiVersion: v1
kind: Pod
metadata:
  name: busybox-sleep
spec:
  containers:
  - name: busybox
    image: busybox
    args:
    - sleep
    - "1000000"
---
apiVersion: v1
kind: Pod
metadata:
  name: busybox-sleep-less
spec:
  containers:
  - name: busybox
    image: busybox
    args:
    - sleep
    - "1000"
EOF
# Create a Secret with literal values
cat <<EOF | kubectl create -f -
apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
data:
  password: $(echo "s33msi4" | base64)
  username: $(echo "jane" | base64)
EOF</code>

Display and Find Resources

<code># List all services
kubectl get services
# List all pods in all namespaces
kubectl get pods --all-namespaces
# Show pods with wide output
kubectl get pods -o wide
# Get a specific deployment
kubectl get deployment my-dep
# Include uninitialized pods
kubectl get pods --include-uninitialized
# Describe a node or pod
kubectl describe nodes my-node
kubectl describe pods my-pod
# Sort services by name
kubectl get services --sort-by=.metadata.name
# Sort pods by restart count
kubectl get pods --sort-by='.status.containerStatuses[0].restartCount'
# Get label values via jsonpath
kubectl get pods --selector=app=cassandra -o jsonpath='{.items[*].metadata.labels.version}'
# Get ExternalIP of all nodes
kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="ExternalIP")].address}'
# List pods using a specific Secret
kubectl get pods -o json | jq '.items[].spec.containers[].env[]?.valueFrom.secretKeyRef.name' | grep -v null | sort | uniq</code>

Update Resources

<code># Rolling update a pod
kubectl rolling-update frontend-v1 -f frontend-v2.json
# Update image during rolling update
kubectl rolling-update frontend-v1 frontend-v2 --image=image:v2
# Force replace a resource from stdin
cat pod.json | kubectl replace -f -
# Force replace (deletes then recreates)
kubectl replace --force -f ./pod.json
# Expose a replication controller as a service
kubectl expose rc nginx --port=80 --target-port=8000
# Update image tag in a pod definition
kubectl get pod mypod -o yaml | sed 's/\(image: myimage\):.*$/\1:v4/' | kubectl replace -f -
# Add a label
kubectl label pods my-pod new-label=awesome
# Add an annotation
kubectl annotate pods my-pod icon-url=http://goo.gl/XXBTWq
# Autoscale a deployment
kubectl autoscale deployment foo --min=2 --max=10</code>

Patch Resources

<code># Patch a node to be unschedulable
kubectl patch node k8s-node-1 -p '{"spec":{"unschedulable":true}}'
# Patch a pod's container image (merge patch)
kubectl patch pod valid-pod -p '{"spec":{"containers":[{"name":"kubernetes-serve-hostname","image":"new image"}]}}'
# JSON patch to change image
kubectl patch pod valid-pod --type='json' -p='[{"op": "replace", "path": "/spec/containers/0/image", "value":"new image"}]'
# JSON patch to remove livenessProbe from a deployment
kubectl patch deployment valid-deployment --type json -p='[{"op": "remove", "path": "/spec/template/spec/containers/0/livenessProbe"}]'</code>

Edit Resources

<code># Edit a service with default editor
kubectl edit svc/docker-registry
# Use a specific editor (nano)
KUBE_EDITOR="nano" kubectl edit svc/docker-registry</code>

Scale Resources

<code># Scale a replicaset
kubectl scale --replicas=3 rs/foo
# Scale from a manifest file
kubectl scale --replicas=3 -f foo.yaml
# Scale a deployment from 2 to 3 replicas
kubectl scale --current-replicas=2 --replicas=3 deployment/mysql
# Scale multiple replication controllers
kubectl scale --replicas=5 rc/foo rc/bar rc/baz</code>

Delete Resources

<code># Delete resources defined in a file
kubectl delete -f ./pod.json
# Delete specific pod and service
kubectl delete pod,service baz foo
# Delete by label
kubectl delete pods,services -l name=myLabel
# Delete including uninitialized
kubectl delete pods,services -l name=myLabel --include-uninitialized
# Delete all pods and services in a namespace
kubectl -n my-ns delete po,svc --all</code>

Interact with Running Pods

<code># Show pod logs
kubectl logs my-pod
# Show container logs
kubectl logs my-pod -c my-container
# Stream logs
kubectl logs -f my-pod
kubectl logs -f my-pod -c my-container
# Run an interactive shell in a pod
kubectl run -i --tty busybox --image=busybox -- sh
# Attach to a running container
kubectl attach my-pod -i
# Port‑forward
kubectl port-forward my-pod 5000:6000
# Execute a command in a container
kubectl exec my-pod -- ls /
kubectl exec my-pod -c my-container -- ls /
# Show metrics for a pod
kubectl top pod POD_NAME --containers</code>

Interact with Nodes and Cluster

<code># Mark node unschedulable
kubectl cordon my-node
# Drain node for maintenance
kubectl drain my-node
# Mark node schedulable again
kubectl uncordon my-node
# Show node metrics
kubectl top node my-node
# Cluster info
kubectl cluster-info
# Dump cluster state
kubectl cluster-info dump
kubectl cluster-info dump --output-directory=/path/to/cluster-state
# Taint a node
kubectl taint nodes foo dedicated=special-user:NoSchedule</code>

kubectl set Command

The

kubectl set

family modifies resources such as environment variables, images, resources, selectors, and service accounts.

kubectl set resources

<code># Set CPU limit and memory for a deployment's nginx container
kubectl set resources deployment nginx -c=nginx --limits=cpu=200m,memory=512Mi
# Set both requests and limits
kubectl set resources deployment nginx --limits=cpu=200m,memory=512Mi --requests=cpu=100m,memory=256Mi
# Remove resource limits
kubectl set resources deployment nginx --limits=cpu=0,memory=0 --requests=cpu=0,memory=0</code>

kubectl set selector

Sets or replaces the selector of a resource (currently only Service).

<code># Set selector (must start with a letter or number, max 63 chars)
kubectl set selector svc/my-service app=frontend --resource-version=12345</code>

kubectl set image

<code># Update image of a deployment's container
kubectl set image deployment/nginx nginx=nginx:1.9.1
# Update all deployments and replication controllers
kubectl set image deployments,rc nginx=nginx:1.9.1 --all
# Update all containers in a daemonset
kubectl set image daemonset abc *=nginx:1.9.1
# Update image from a local file (local mode)
kubectl set image -f path/to/file.yaml nginx=nginx:1.9.1 --local -o yaml</code>

Resource Types

The table below lists all supported Kubernetes resource kinds and their short names.

Formatting Output

Use

-o

or

--output

to specify output format (json, yaml, wide, etc.). Increase verbosity with

-v

or

--v

followed by an integer.

Kubectl detailed output and debugging