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

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