Master Kubernetes with Essential kubectl Commands: From Cluster Overview to Advanced Ops

Cluster Overview

# Show basic cluster information
kubectl cluster-info

# List all nodes with extended details
kubectl get nodes -o wide

# Describe a specific node (replace NODE_NAME)
kubectl describe node NODE_NAME

# Show resource usage for nodes and pods
kubectl top nodes
kubectl top pods --all-namespaces

Namespace Management

# List all namespaces
kubectl get namespaces

# Create a new namespace (replace NAMESPACE)
kubectl create namespace NAMESPACE

# Delete a namespace (use with caution)
kubectl delete namespace NAMESPACE

# Set the default namespace for the current context
kubectl config set-context --current --namespace=NAMESPACE

Pod Lifecycle Management

Basic Pod Operations

# List all pods across all namespaces
kubectl get pods --all-namespaces

# List pods in a specific namespace (replace NAMESPACE)
kubectl get pods -n NAMESPACE

# Watch pod status changes in real time
kubectl get pods -w

# Show detailed information for a pod (replace POD_NAME and NAMESPACE)
kubectl describe pod POD_NAME -n NAMESPACE

# Delete a pod
kubectl delete pod POD_NAME -n NAMESPACE

# Force‑delete a stuck pod
kubectl delete pod POD_NAME --grace-period=0 --force

Advanced Pod Queries

# Query pods by label selector (e.g., app=nginx)
kubectl get pods -l app=nginx

# Query pods by field selector (e.g., Running phase)
kubectl get pods --field-selector status.phase=Running

# Output a pod's full YAML definition (replace POD_NAME)
kubectl get pod POD_NAME -o yaml

# Show resource usage for a specific pod
kubectl top pod POD_NAME

# List pod names with their phases using JSONPath
kubectl get pods -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.phase}{"
"}{end}'

Service and Network Management

Service Operations

# List all services in all namespaces
kubectl get services --all-namespaces

# Describe a specific service (replace SERVICE_NAME)
kubectl describe service SERVICE_NAME

# Show service endpoints
kubectl get endpoints SERVICE_NAME

# Port‑forward to a pod for debugging (replace POD_NAME)
kubectl port-forward pod/POD_NAME 8080:80

# Port‑forward to a service for debugging (replace SERVICE_NAME)
kubectl port-forward service/SERVICE_NAME 8080:80

# Find pods selected by a service's selector (replace SERVICE_SELECTOR)
kubectl get pods -l SERVICE_SELECTOR

Ingress Management

# List all Ingress resources
kubectl get ingress --all-namespaces

# Describe a specific Ingress (replace INGRESS_NAME)
kubectl describe ingress INGRESS_NAME

# View Ingress controller logs (example assumes nginx‑ingress)
kubectl logs -n ingress-nginx deployment/nginx-ingress-controller

Network Policies and Connectivity Testing

# List all NetworkPolicies
kubectl get networkpolicies --all-namespaces

# Test connectivity between pods (replace POD_NAME and TARGET_IP)
kubectl exec -it POD_NAME -- ping TARGET_IP
kubectl exec -it POD_NAME -- nslookup SERVICE_NAME

# View a pod's DNS configuration (replace POD_NAME)
kubectl exec -it POD_NAME -- cat /etc/resolv.conf

Configuration and Storage Management

ConfigMap and Secret

# List all ConfigMaps
kubectl get configmaps --all-namespaces

# Show a ConfigMap's content (replace CONFIGMAP_NAME)
kubectl describe configmap CONFIGMAP_NAME
kubectl get configmap CONFIGMAP_NAME -o yaml

# Create a ConfigMap from a file or literal
kubectl create configmap NAME --from-file=FILE_PATH
kubectl create configmap NAME --from-literal=key=value

# List all Secrets
kubectl get secrets --all-namespaces

# Retrieve a Secret's data (Base64‑decoded) (replace SECRET_NAME)
kubectl get secret SECRET_NAME -o jsonpath='{.data.password}' | base64 -d

Persistent Storage

# List PersistentVolumes
kubectl get pv

# List PersistentVolumeClaims
kubectl get pvc --all-namespaces

# Show StorageClasses
kubectl get storageclass

# Describe a PV or PVC (replace PV_NAME or PVC_NAME)
kubectl describe pv PV_NAME
kubectl describe pvc PVC_NAME

Troubleshooting Techniques

Log Inspection

# View logs of a pod (replace POD_NAME and NAMESPACE)
kubectl logs POD_NAME -n NAMESPACE

# View logs of a specific container in a multi‑container pod (replace CONTAINER_NAME)
kubectl logs POD_NAME -c CONTAINER_NAME

# Follow logs in real time
kubectl logs -f POD_NAME

# Show logs of a previous (crashed) container
kubectl logs POD_NAME --previous

# Show logs from the last hour or from a specific timestamp
kubectl logs POD_NAME --since=1h
kubectl logs POD_NAME --since-time=2024-01-01T00:00:00Z

# Export logs of all pods to separate files (bash loop)
for pod in $(kubectl get pods -o name); do
  kubectl logs $pod > ${pod##*/}.log 2>&1
done

Event Analysis and Debugging

# List recent events sorted by timestamp
kubectl get events --sort-by='.lastTimestamp'

# Describe a specific resource to see its events (replace RESOURCE_TYPE and RESOURCE_NAME)
kubectl describe RESOURCE_TYPE RESOURCE_NAME

# Watch live changes of pods or events
kubectl get pods -w
kubectl get events -w

# Check node resource allocation details (replace NODE_NAME)
kubectl describe node NODE_NAME | grep -A5 "Allocated resources"

Container Debugging

# Open a shell inside a container (replace POD_NAME)
kubectl exec -it POD_NAME -- /bin/bash
kubectl exec -it POD_NAME -- /bin/sh

# Execute a command in a specific container of a multi‑container pod (replace CONTAINER_NAME)
kubectl exec -it POD_NAME -c CONTAINER_NAME -- /bin/bash

# Copy files to/from a container (replace LOCAL_FILE, CONTAINER_PATH)
kubectl cp LOCAL_FILE POD_NAME:CONTAINER_PATH
kubectl cp POD_NAME:CONTAINER_PATH LOCAL_FILE

# Run a temporary debug pod
kubectl run debug-pod --rm -it --image=busybox -- /bin/sh

# Debug with a specialized image (e.g., netshoot)
kubectl debug POD_NAME -it --image=nicolaka/netshoot

Performance Monitoring & Optimization

Resource Monitoring

# Show node resource usage
kubectl top nodes

# Show pod resource usage across the cluster
kubectl top pods --all-namespaces

# Show pod usage in a specific namespace (replace NAMESPACE)
kubectl top pods -n NAMESPACE

# Sort pods by CPU or memory usage
kubectl top pods --sort-by=cpu
kubectl top pods --sort-by=memory

Scaling and Rollout Management

# Manually scale a Deployment (replace DEPLOYMENT_NAME)
kubectl scale deployment DEPLOYMENT_NAME --replicas=5

# View Horizontal Pod Autoscaler (HPA) status
kubectl get hpa

# View Vertical Pod Autoscaler (VPA) status
kubectl get vpa

# Check rollout status of a Deployment
kubectl rollout status deployment/DEPLOYMENT_NAME

# View rollout history
kubectl rollout history deployment/DEPLOYMENT_NAME

# Roll back to the previous version
kubectl rollout undo deployment/DEPLOYMENT_NAME

Resource Quota Management

# List resource quotas
kubectl get resourcequota --all-namespaces

# List LimitRanges
kubectl get limitrange --all-namespaces

# Describe a specific quota (replace QUOTA_NAME)
kubectl describe resourcequota QUOTA_NAME

Advanced Operations Tricks

Batch Actions & Automation

# Delete all Evicted pods
kubectl get pods --all-namespaces | grep Evicted | awk '{print $1, $2}' | xargs -n2 kubectl delete pod -n

# Restart all Deployments
kubectl get deployments -o name | xargs -I {} kubectl rollout restart {}

# Export image information of all pods
kubectl get pods --all-namespaces -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.containers[*].image}{"
"}{end}'

# Find pods without resource limits (requires jq)
kubectl get pods --all-namespaces -o json | jq '.items[] | select(.spec.containers[].resources.limits == null) | .metadata.name'

Security & Permission Management

# Show current user permissions
kubectl auth can-i --list

# Test a specific permission for a user (replace USERNAME)
kubectl auth can-i create pods --as=USERNAME

# List RBAC roles and bindings
kubectl get roles,rolebindings --all-namespaces
kubectl get clusterroles,clusterrolebindings

# List service accounts
kubectl get serviceaccounts --all-namespaces

# Show PodSecurityPolicies
kubectl get podsecuritypolicies

Cluster Maintenance & Backup

# Drain a node for maintenance (replace NODE_NAME)
kubectl drain NODE_NAME --ignore-daemonsets --delete-emptydir-data

# Mark a node unschedulable
kubectl cordon NODE_NAME

# Make a node schedulable again
kubectl uncordon NODE_NAME

# Export all cluster resources to YAML (backup)
kubectl get all --all-namespaces -o yaml > cluster-backup.yaml

# Export ConfigMaps and Secrets separately
kubectl get configmaps --all-namespaces -o yaml > configmaps-backup.yaml
kubectl get secrets --all-namespaces -o yaml > secrets-backup.yaml

Command‑Line Ergonomics

# Create shortcuts for frequent commands
alias k='kubectl'
alias kgp='kubectl get pods'
alias kgs='kubectl get services'
alias kgn='kubectl get nodes'
alias kdp='kubectl describe pod'
alias kl='kubectl logs'

# Switch clusters quickly (requires kubectx)
kubectx CLUSTER_NAME

# Switch namespaces quickly (requires kubens)
kubens NAMESPACE