K8s deploy

Kubernetes Deployment

Safe deployment practices, rollout strategies, and rollback procedures.

When to Use This Skill

Use this skill when:

• Deploying new application versions
• Rolling back failed deployments
• Scaling applications
• Managing deployment strategies

Pre-Deployment Checklist

1. Cluster Health Check

# Nodes ready?
kubectl get nodes

# Any problematic pods?
kubectl get pods -A | grep -v Running | grep -v Completed

# Resource availability
kubectl top nodes

2. Image Verification

# Verify image exists (example with Docker Hub)
docker manifest inspect <image>:<tag>

# Check current image
kubectl get deployment <name> -o jsonpath='{.spec.template.spec.containers[0].image}'

3. Current State Backup

# Save current deployment spec
kubectl get deployment <name> -o yaml > deployment-backup.yaml

# Note current revision
kubectl rollout history deployment/<name>

Deployment Methods

Update Image (Most Common)

# Update container image
kubectl set image deployment/<name> <container>=<image>:<tag>

# Example
kubectl set image deployment/nginx nginx=nginx:1.25

# Watch rollout
kubectl rollout status deployment/<name>

Apply Manifest

# Dry-run first (ALWAYS)
kubectl apply -f deployment.yaml --dry-run=client

# Show diff
kubectl diff -f deployment.yaml

# Apply
kubectl apply -f deployment.yaml

# Watch
kubectl rollout status deployment/<name>

Patch Deployment

# Strategic merge patch
kubectl patch deployment <name> -p '{"spec":{"replicas":5}}'

# JSON patch
kubectl patch deployment <name> --type='json' \
  -p='[{"op":"replace","path":"/spec/replicas","value":5}]'

Rollout Management

Check Rollout Status

# Status
kubectl rollout status deployment/<name>

# History
kubectl rollout history deployment/<name>

# Specific revision details
kubectl rollout history deployment/<name> --revision=2

Pause/Resume Rollout

# Pause (for canary-style manual control)
kubectl rollout pause deployment/<name>

# Resume
kubectl rollout resume deployment/<name>

Rollback

# Rollback to previous version
kubectl rollout undo deployment/<name>

# Rollback to specific revision
kubectl rollout undo deployment/<name> --to-revision=2

# Verify rollback
kubectl rollout status deployment/<name>

Scaling

Manual Scaling

# Scale replicas
kubectl scale deployment/<name> --replicas=5

# Scale multiple
kubectl scale deployment/<name1> deployment/<name2> --replicas=3

Autoscaling (HPA)

# Create HPA
kubectl autoscale deployment/<name> --min=2 --max=10 --cpu-percent=80

# Check HPA status
kubectl get hpa

# Describe HPA
kubectl describe hpa <name>

Deployment Strategies

Rolling Update (Default)

spec:
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 25%        # Max pods over desired
      maxUnavailable: 25%  # Max pods unavailable

# Check current strategy
kubectl get deployment <name> -o jsonpath='{.spec.strategy}'

Recreate

spec:
  strategy:
    type: Recreate  # Kill all, then create new

Blue-Green (Manual)

# Deploy new version with different label
kubectl apply -f deployment-v2.yaml

# Verify v2 is healthy
kubectl get pods -l version=v2

# Switch service to v2
kubectl patch service <name> -p '{"spec":{"selector":{"version":"v2"}}}'

# Rollback: switch back to v1
kubectl patch service <name> -p '{"spec":{"selector":{"version":"v1"}}}'

Canary (Manual)

# Scale down main, scale up canary
kubectl scale deployment/<name>-main --replicas=9
kubectl scale deployment/<name>-canary --replicas=1

# Monitor canary metrics, then promote or rollback

Post-Deployment Verification

Health Checks

# Pods running?
kubectl get pods -l app=<name>

# Ready and healthy?
kubectl get deployment <name>

# Events (errors?)
kubectl get events --field-selector involvedObject.name=<deployment> --sort-by='.lastTimestamp'

Smoke Tests

# Port-forward and test
kubectl port-forward deployment/<name> 8080:80 &
curl localhost:8080/health

# Or exec into pod
kubectl exec -it deployment/<name> -- curl localhost/health

Compare Metrics

# Check resource usage
kubectl top pods -l app=<name>

# Compare with previous
# (Use your monitoring: Prometheus, Datadog, etc.)

Troubleshooting Failed Deployments

Deployment Stuck

# Check rollout status
kubectl rollout status deployment/<name>

# Check events
kubectl describe deployment <name>

# Check pod issues
kubectl get pods -l app=<name>
kubectl describe pod <problematic-pod>

Common Issues

Symptom	Check	Fix
ImagePullBackOff	Image name/tag, registry auth	Fix image reference
CrashLoopBackOff	Pod logs	Fix application error
Pending pods	Node resources, PVC	Scale cluster or fix storage
Readiness probe failing	App startup time	Adjust probe timing

Emergency Rollback

# Immediate rollback
kubectl rollout undo deployment/<name>

# If that fails, scale to zero then restore from backup
kubectl scale deployment/<name> --replicas=0
kubectl apply -f deployment-backup.yaml

Safe Deployment Workflow

# 1. Pre-flight
kubectl get nodes && kubectl top nodes

# 2. Backup current state
kubectl get deployment <name> -o yaml > backup.yaml

# 3. Dry-run
kubectl apply -f new-deployment.yaml --dry-run=client

# 4. Show diff
kubectl diff -f new-deployment.yaml

# 5. Apply with record
kubectl apply -f new-deployment.yaml

# 6. Watch rollout
kubectl rollout status deployment/<name> --timeout=5m

# 7. Verify health
kubectl get pods -l app=<name>
kubectl logs -l app=<name> --tail=20

# 8. If issues: rollback
kubectl rollout undo deployment/<name>

Related Skills

• k8s-debug: For troubleshooting deployment issues
• argocd-gitops: For GitOps-based deployments
• incident-response: When deployments cause incidents