Kubernetes Multi-Cluster Quick Reference

8 minute read

Essential Multi-Cluster Commands

Context Switching

Command	Description
`kubectx`	List all contexts
`kubectx east`	Switch to east cluster
`kubectx -`	Switch to previous context
`kubectx -c`	Show current context
`kubectl config get-contexts`	List contexts with details
`kubectl config current-context`	Show current context

Namespace Operations

Command	Description
`kubens`	List namespaces
`kubens ecommerce`	Switch to namespace
`kubens -`	Switch to previous namespace
`kubectl config set-context --current --namespace=ecommerce`	Set default namespace

Multi-Cluster Operations

# Apply to all clusters
for ctx in east west; do
  kubectl apply -f deployment.yaml --context=$ctx
done

# Get status from all clusters
for ctx in east west; do
  echo "=== $ctx ==="
  kubectl get pods -n ecommerce --context=$ctx
done

# Compare deployments
diff \
  <(kubectl get deploy -n ecommerce --context=east -o yaml) \
  <(kubectl get deploy -n ecommerce --context=west -o yaml)

# Scale across clusters
kubectl scale deployment product-service --replicas=5 -n ecommerce --context=east
kubectl scale deployment product-service --replicas=3 -n ecommerce --context=west

Resource Management Quick Reference

Pod Operations

Command	Description
`k get pods -n ecommerce`	List pods
`k get pods -o wide`	Show node and IP
`k describe pod <name>`	Detailed info
`k logs <pod>`	View logs
`k logs <pod> -f`	Follow logs
`k logs <pod> --previous`	Previous container logs
`k exec -it <pod> -- /bin/sh`	Shell into pod
`k delete pod <name>`	Delete pod
`k delete pod <name> --grace-period=0 --force`	Force delete

Deployment Operations

Command	Description
`k get deploy`	List deployments
`k describe deploy <name>`	Deployment details
`k scale deploy <name> --replicas=5`	Scale deployment
`k set image deploy/<name> container=image:tag`	Update image
`k rollout status deploy/<name>`	Check rollout status
`k rollout history deploy/<name>`	View rollout history
`k rollout undo deploy/<name>`	Rollback deployment
`k rollout restart deploy/<name>`	Restart all pods

Service Operations

Command	Description
`k get svc`	List services
`k describe svc <name>`	Service details
`k get endpoints <name>`	Show endpoints
`k port-forward svc/<name> 8080:80`	Port forward service

Debugging Commands

Network Debugging

# DNS test
kubectl run dns-test --image=busybox:1.28 --rm -it --restart=Never -- nslookup kubernetes.default

# Connectivity test
kubectl run curl-test --image=curlimages/curl --rm -it --restart=Never -- \
  curl -v http://product-service.ecommerce.svc.cluster.local:8080

# Network troubleshooting pod
kubectl run netshoot --image=nicolaka/netshoot --rm -it --restart=Never -- bash

Resource Monitoring

# Top commands
kubectl top nodes
kubectl top pods -n ecommerce
kubectl top pods -n ecommerce --sort-by=cpu
kubectl top pods -n ecommerce --sort-by=memory

# Watch resources
watch -n 2 kubectl get pods -n ecommerce
kubectl get pods -n ecommerce -w

# Events
kubectl get events -n ecommerce --sort-by='.lastTimestamp'
kubectl get events -n ecommerce --field-selector type=Warning

Log Aggregation

# Multiple pod logs with stern
stern -n ecommerce product-service
stern -n ecommerce product-service --since 5m
stern -n ecommerce "product-.*" --tail 50

# All logs from deployment
kubectl logs -n ecommerce -l app=product-service --all-containers=true

# Previous logs from all pods
kubectl logs -n ecommerce -l app=product-service --previous --all-containers=true

JSONPath Queries

Common Queries

# Get pod IPs
kubectl get pods -n ecommerce -o jsonpath='{.items[*].status.podIP}'

# Get pod names and nodes
kubectl get pods -n ecommerce -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.nodeName}{"\n"}{end}'

# Get all container images
kubectl get pods -n ecommerce -o jsonpath='{.items[*].spec.containers[*].image}' | tr ' ' '\n' | sort -u

# Get resource requests
kubectl get pods -n ecommerce -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.containers[*].resources.requests}{"\n"}{end}'

# Get restart counts
kubectl get pods -n ecommerce -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.containerStatuses[*].restartCount}{"\n"}{end}'

Configuration Management

ConfigMaps

# Create from literal
kubectl create configmap app-config --from-literal=key1=value1 --from-literal=key2=value2 -n ecommerce

# Create from file
kubectl create configmap app-config --from-file=config.yaml -n ecommerce

# View configmap
kubectl get configmap app-config -o yaml -n ecommerce

# Edit configmap
kubectl edit configmap app-config -n ecommerce

# Delete configmap
kubectl delete configmap app-config -n ecommerce

Secrets

# Create generic secret
kubectl create secret generic db-secret \
  --from-literal=username=admin \
  --from-literal=password=secret123 \
  -n ecommerce

# Create TLS secret
kubectl create secret tls tls-secret \
  --cert=path/to/cert.crt \
  --key=path/to/cert.key \
  -n ecommerce

# View secret (base64 encoded)
kubectl get secret db-secret -o yaml -n ecommerce

# Decode secret
kubectl get secret db-secret -o jsonpath='{.data.password}' -n ecommerce | base64 -d

# Delete secret
kubectl delete secret db-secret -n ecommerce

Scaling and Performance

Horizontal Pod Autoscaler

# Create HPA
kubectl autoscale deployment product-service \
  --cpu-percent=70 \
  --min=3 \
  --max=10 \
  -n ecommerce

# Get HPA status
kubectl get hpa -n ecommerce

# Watch HPA
kubectl get hpa -n ecommerce -w

# Describe HPA
kubectl describe hpa product-service-hpa -n ecommerce

# Delete HPA
kubectl delete hpa product-service-hpa -n ecommerce

Resource Management

# Set resource limits
kubectl set resources deployment product-service \
  --requests=cpu=200m,memory=256Mi \
  --limits=cpu=1000m,memory=512Mi \
  -n ecommerce

# Check resource usage
kubectl describe nodes | grep -A 5 "Allocated resources"

# Get pod QoS class
kubectl get pods -n ecommerce -o custom-columns=NAME:.metadata.name,QOS:.status.qosClass

Troubleshooting Scenarios

Pod Stuck in Pending

# Check events
kubectl describe pod <pod-name> -n ecommerce | grep -A 10 Events

# Check node resources
kubectl describe nodes

# Check PVC status
kubectl get pvc -n ecommerce

# Check node selector/affinity
kubectl get pod <pod-name> -n ecommerce -o yaml | grep -A 10 nodeSelector

Pod CrashLoopBackOff

# Check logs
kubectl logs <pod-name> -n ecommerce --previous

# Check liveness/readiness probes
kubectl describe pod <pod-name> -n ecommerce | grep -A 5 "Liveness\|Readiness"

# Check events
kubectl get events -n ecommerce --field-selector involvedObject.name=<pod-name>

# Describe pod
kubectl describe pod <pod-name> -n ecommerce

Service Not Accessible

# Check service
kubectl get svc <service-name> -n ecommerce
kubectl describe svc <service-name> -n ecommerce

# Check endpoints
kubectl get endpoints <service-name> -n ecommerce

# Verify pod labels match service selector
kubectl get pods -n ecommerce --show-labels
kubectl describe svc <service-name> -n ecommerce | grep Selector

# Test from within cluster
kubectl run test --image=curlimages/curl -it --rm --restart=Never -n ecommerce -- \
  curl -v http://<service-name>.<namespace>.svc.cluster.local:<port>

Node Issues

# Check node status
kubectl get nodes
kubectl describe node <node-name>

# Check node conditions
kubectl get nodes -o json | jq '.items[] | {name:.metadata.name, conditions:.status.conditions}'

# Drain node
kubectl drain <node-name> --ignore-daemonsets --delete-emptydir-data

# Uncordon node
kubectl uncordon <node-name>

# Mark node unschedulable
kubectl cordon <node-name>

Security Commands

RBAC

# Check permissions
kubectl auth can-i create deployments -n ecommerce
kubectl auth can-i delete pods --all-namespaces

# Check as service account
kubectl auth can-i get pods \
  --as=system:serviceaccount:ecommerce:product-service-sa \
  -n ecommerce

# List permissions
kubectl auth can-i --list -n ecommerce

Network Policies

# List network policies
kubectl get networkpolicy -n ecommerce

# Describe policy
kubectl describe networkpolicy <policy-name> -n ecommerce

# Test connectivity
kubectl run test-$RANDOM --image=busybox --rm -it --restart=Never -n ecommerce -- \
  wget --spider --timeout=1 http://product-service:8080

Batch Operations

# Delete all pods with status
kubectl delete pods --field-selector status.phase=Failed -n ecommerce
kubectl delete pods --field-selector status.phase=Succeeded -n ecommerce

# Restart all deployments
kubectl rollout restart deployment --all -n ecommerce

# Label all pods
kubectl label pods --all environment=production -n ecommerce

# Get all resource types
kubectl get all -n ecommerce

# Delete all resources
kubectl delete all --all -n ecommerce

# Export all resources
kubectl get all -n ecommerce -o yaml > backup.yaml

Useful Aliases

Add to ~/.zshrc:

# Kubectl aliases
alias k='kubectl'
alias kgp='kubectl get pods'
alias kgs='kubectl get svc'
alias kgd='kubectl get deployments'
alias kga='kubectl get all'
alias kgn='kubectl get nodes'

# Describe aliases
alias kdp='kubectl describe pod'
alias kds='kubectl describe service'
alias kdd='kubectl describe deployment'

# Logs aliases
alias kl='kubectl logs'
alias klf='kubectl logs -f'
alias klp='kubectl logs --previous'

# Execute aliases
alias kex='kubectl exec -it'

# Delete aliases
alias kdel='kubectl delete'
alias kdelp='kubectl delete pod'

# Context aliases
alias kctx='kubectl config use-context'
alias kcurrent='kubectl config current-context'
alias kns='kubectl config set-context --current --namespace'

# Watch aliases
alias kwatch='watch -n 2 kubectl get pods'
alias kwatchd='watch -n 2 kubectl get deployments'

# Multi-cluster aliases
alias keast='kubectl config use-context east'
alias kwest='kubectl config use-context west'

# Apply source
source ~/.zshrc

Quick Diagnostic Script

#!/bin/bash
# Save as k8s-diagnostic.sh

NAMESPACE=${1:-ecommerce}
CONTEXT=${2:-$(kubectl config current-context)}

echo "=== Kubernetes Diagnostic Report ==="
echo "Context: $CONTEXT"
echo "Namespace: $NAMESPACE"
echo "Time: $(date)"
echo

echo "=== Nodes ==="
kubectl get nodes --context=$CONTEXT
echo

echo "=== Pods ==="
kubectl get pods -n $NAMESPACE --context=$CONTEXT -o wide
echo

echo "=== Services ==="
kubectl get svc -n $NAMESPACE --context=$CONTEXT
echo

echo "=== Deployments ==="
kubectl get deployments -n $NAMESPACE --context=$CONTEXT
echo

echo "=== HPA ==="
kubectl get hpa -n $NAMESPACE --context=$CONTEXT 2>/dev/null || echo "No HPA found"
echo

echo "=== Recent Events ==="
kubectl get events -n $NAMESPACE --context=$CONTEXT --sort-by='.lastTimestamp' | tail -10
echo

echo "=== Resource Usage ==="
kubectl top nodes --context=$CONTEXT 2>/dev/null || echo "Metrics server not available"
kubectl top pods -n $NAMESPACE --context=$CONTEXT 2>/dev/null || echo "Metrics server not available"

Usage:

chmod +x k8s-diagnostic.sh
./k8s-diagnostic.sh ecommerce east
./k8s-diagnostic.sh ecommerce west

Performance Tuning Tips

Pod Optimization

Always set resource requests and limits
Use readiness probes to prevent premature traffic
Use liveness probes for automatic restart
Configure appropriate termination grace period
Use init containers for setup tasks

Deployment Strategies

# Rolling update with max surge/unavailable
kubectl patch deployment product-service -p '{
  "spec": {
    "strategy": {
      "type": "RollingUpdate",
      "rollingUpdate": {
        "maxSurge": 1,
        "maxUnavailable": 0
      }
    }
  }
}' -n ecommerce

# Blue-green: switch service selector
kubectl patch service product-service -p '{
  "spec": {
    "selector": {
      "version": "v2"
    }
  }
}' -n ecommerce

Resource Quotas

apiVersion: v1
kind: ResourceQuota
metadata:
  name: ecommerce-quota
  namespace: ecommerce
spec:
  hard:
    requests.cpu: "10"
    requests.memory: 20Gi
    limits.cpu: "20"
    limits.memory: 40Gi
    persistentvolumeclaims: "10"
    pods: "50"

Monitoring Checklist

Common Issues and Solutions

Issue	Diagnosis	Solution
ImagePullBackOff	Check image name and registry access	Verify image exists, check secrets
CrashLoopBackOff	Check application logs	Fix application errors, check probes
Pending pods	Check node resources and taints	Scale cluster or adjust requests
Service unreachable	Check endpoints and selectors	Fix label matching
High latency	Check resource usage	Scale up or optimize app
OOMKilled	Check memory limits	Increase limits or fix memory leaks

Best Practices Summary

Always use namespaces for resource isolation
Set resource requests and limits for predictable performance
Use labels and selectors consistently
Implement health checks (liveness and readiness)
Use ConfigMaps and Secrets for configuration
Enable autoscaling (HPA) for dynamic workloads
Implement network policies for security
Use StatefulSets for stateful applications
Regular backups of cluster configuration
Monitor everything - resources, logs, metrics

This quick reference provides essential commands and patterns for managing multi-cluster Kubernetes deployments!

Essential Multi-Cluster Commands

Context Switching

Namespace Operations

Multi-Cluster Operations

Resource Management Quick Reference

Pod Operations

Deployment Operations

Service Operations

Debugging Commands

Network Debugging

Resource Monitoring

Log Aggregation

JSONPath Queries

Common Queries

Configuration Management

ConfigMaps

Secrets

Scaling and Performance

Horizontal Pod Autoscaler

Resource Management

Troubleshooting Scenarios

Pod Stuck in Pending

Pod CrashLoopBackOff

Service Not Accessible

Node Issues

Security Commands

RBAC

Network Policies

Batch Operations

Useful Aliases

Quick Diagnostic Script

Performance Tuning Tips

Pod Optimization

Deployment Strategies

Resource Quotas

Monitoring Checklist

Common Issues and Solutions

Best Practices Summary

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