Kubernetes (kubectl)

Container orchestration platform for automating deployment, scaling, and management.

Basic Commands

COMMAND	DESCRIPTION
kubectl get pods	List all pods
kubectl get svc	List all services
kubectl get deploy	List all deployments
kubectl get nodes	List cluster nodes
kubectl get all	List all resources
kubectl get <resource> -n <namespace>	List resources in namespace

Creating & Applying

COMMAND	DESCRIPTION
kubectl apply -f file.yaml	Apply configuration
kubectl create -f file.yaml	Create resource from file
kubectl delete -f file.yaml	Delete resources from file
kubectl run <name> --image=<image>	Run a pod

Pod Management

COMMAND	DESCRIPTION
kubectl describe pod <pod>	Show pod details
kubectl logs <pod>	Show pod logs
kubectl logs -f <pod>	Follow pod logs
kubectl exec -it <pod> -- /bin/bash	Execute command in pod
kubectl port-forward <pod> 8080:80	Forward port to local
kubectl delete pod <pod>	Delete a pod
kubectl top pod <pod>	Show pod resource usage

Deployment Management

COMMAND	DESCRIPTION
kubectl scale deploy <name> --replicas=3	Scale deployment
kubectl rollout status deploy/<name>	Check rollout status
kubectl rollout history deploy/<name>	Show deployment history
kubectl rollout undo deploy/<name>	Rollback to previous
kubectl rollout undo deploy/<name> --to-revision=2	Rollback to specific version

Namespace Management

COMMAND	DESCRIPTION
kubectl create namespace <name>	Create namespace
kubectl delete namespace <name>	Delete namespace
kubectl config set-context --current --namespace=<name>	Set default namespace

ConfigMaps & Secrets

COMMAND	DESCRIPTION
kubectl create configmap <name> --from-file=path	Create ConfigMap from file
kubectl create secret generic <name> --from-literal=key=value	Create secret
kubectl get secrets	List secrets
kubectl get configmaps	List ConfigMaps

Service & Ingress

COMMAND	DESCRIPTION
kubectl expose pod <pod> --port=80 --type=LoadBalancer	Expose pod as service
kubectl get ingress	List ingress resources
kubectl describe ingress <name>	Show ingress details

Troubleshooting

COMMAND	DESCRIPTION
kubectl describe <resource> <name>	Show detailed information
kubectl logs <pod> --previous	Show logs from previous container
kubectl get events --sort-by=.metadata.creationTimestamp	List cluster events
kubectl cluster-info	Show cluster info
kubectl get componentstatuses	Check component status

YAML Examples

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.21
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"

Service

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: LoadBalancer

ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  app.properties: |
    key=value
    debug=true

Useful Flags

FLAG	DESCRIPTION
-o yaml	Output in YAML format
-o json	Output in JSON format
-o wide	Show more details
--watch	Watch for changes
--all-namespaces	Show all namespaces
--field-selector	Filter by field

Resource Management

# Edit resource
kubectl edit <resource> <name>

# Get resource in specific format
kubectl get pod <pod> -o yaml

# Get resource as JSON
kubectl get pod <pod> -o json

# Copy file from pod
kubectl cp <pod>:/path/file ./local-file

Labels & Selectors

# Add label
kubectl label pod <pod> key=value

# Remove label
kubectl label pod <pod> key-

# Select by label
kubectl get pods -l app=nginx

# Select with multiple labels
kubectl get pods -l env=prod,tier=frontend

Context Management

COMMAND	DESCRIPTION
kubectl config get-contexts	List contexts
kubectl config use-context <name>	Switch context
kubectl config current-context	Show current context
kubectl config set-credentials <name>	Set credentials

Quick Checks

# Check cluster health
kubectl get nodes
kubectl get cs

# Check pod status
kubectl get pods -o wide

# Check resource usage
kubectl top nodes
kubectl top pods

# Check everything
kubectl get all --all-namespaces

Best Practices

• Always use resource requests and limits
• Implement health checks (liveness, readiness probes)
• Use namespaces to organize resources
• Use labels and annotations for organization
• Use ConfigMaps for configuration, Secrets for sensitive data
• Implement pod disruption budgets for critical services
• Use taints and tolerations for node scheduling
• Regularly audit RBAC policies

TIP

Use kubectl explain <resource> to get documentation about Kubernetes resources and fields.