Kubernetes Commands

This section provides a comprehensive reference for kubectl commands, including common use cases and best practices.

Basic Commands

Resource Management

# Get resources
kubectl get pods
kubectl get services
kubectl get deployments
kubectl get nodes

# Get resources in all namespaces
kubectl get all --all-namespaces

# Get detailed information about a resource
kubectl describe pod POD_NAME
kubectl describe service SERVICE_NAME
kubectl describe node NODE_NAME

# Delete resources
kubectl delete pod POD_NAME
kubectl delete service SERVICE_NAME
kubectl delete deployment DEPLOYMENT_NAME

Resource Creation

# Create resources from file
kubectl apply -f manifest.yaml

# Create resources from URL
kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/main/content/en/examples/application/deployment.yaml

# Create resources from stdin
cat manifest.yaml | kubectl apply -f -

Common Use Cases

Working with Pods

# Get pod logs
kubectl logs POD_NAME

# Follow pod logs
kubectl logs -f POD_NAME

# Execute command in pod
kubectl exec -it POD_NAME -- /bin/bash

# Port forwarding
kubectl port-forward POD_NAME 8080:80

Managing Deployments

# Scale deployment
kubectl scale deployment DEPLOYMENT_NAME --replicas=3

# Update deployment
kubectl set image deployment/DEPLOYMENT_NAME CONTAINER_NAME=IMAGE_NAME

# Rollback deployment
kubectl rollout undo deployment/DEPLOYMENT_NAME

# View deployment status
kubectl rollout status deployment/DEPLOYMENT_NAME

Working with ConfigMaps and Secrets

# Create ConfigMap from file
kubectl create configmap CONFIG_NAME --from-file=config.yaml

# Create Secret from file
kubectl create secret generic SECRET_NAME --from-file=secret.yaml

# List ConfigMaps and Secrets
kubectl get configmaps
kubectl get secrets

Best Practices

Use Namespaces: Organize resources logically

# Create namespace
kubectl create namespace my-namespace
   
# Set default namespace
kubectl config set-context --current --namespace=my-namespace

Resource Limits: Always set resource limits

resources:
  requests:
    memory: "64Mi"
    cpu: "250m"
  limits:
    memory: "128Mi"
    cpu: "500m"

Health Checks: Implement readiness and liveness probes

readinessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 10

Troubleshooting

Common Issues

Pod Won’t Start

# Check pod events
kubectl describe pod POD_NAME
   
# Check pod logs
kubectl logs POD_NAME

Service Not Accessible

# Check service endpoints
kubectl get endpoints SERVICE_NAME
   
# Check service details
kubectl describe service SERVICE_NAME

Node Issues

# Check node status
kubectl get nodes
   
# Check node details
kubectl describe node NODE_NAME