11.0.7 Cloud Migration Strategy
Moving to the cloud is a journey, not a destination. Let’s explore smart migration strategies that build on your container expertise.
The 6 Rs of Cloud Migration
Note
Moving to the cloud is a process that involves planning, preparation, and execution. It can be a complex and challenging undertaking, but it offers many benefits, including scalability, flexibility, cost savings, and ease of use.
Migration Approaches Overview:
The 6 Rs Migration Strategy:
Rehost (Lift and Shift)
Replatform (Lift, Tinker, and Shift)
Refactor (Re-architect)
Retire (Turn off)
Retain (Keep as is)
Repurchase (Buy new)
1. Rehost (Lift and Shift)
What it means: Move applications to cloud with minimal changes
Traditional Approach:
┌─────────────────────────────────────┐
│ Physical Server │
│ ├─ Windows Server 2019 │
│ ├─ IIS Web Server │
│ ├─ .NET Application │
│ └─ SQL Server Database │
└─────────────────────────────────────┘
│ (Rehost)
▼
┌─────────────────────────────────────┐
│ Cloud Virtual Machine │
│ ├─ Windows Server 2019 │
│ ├─ IIS Web Server │
│ ├─ .NET Application │
│ └─ SQL Server Database │
└─────────────────────────────────────┘
Container-First Rehost:
# Smart rehost using containers
# 1. Containerize your existing application
FROM mcr.microsoft.com/dotnet/aspnet:6.0
WORKDIR /app
COPY published-app/ .
ENTRYPOINT ["dotnet", "MyApp.dll"]
# 2. Deploy to cloud Kubernetes
kubectl apply -f - <<EOF
apiVersion: apps/v1
kind: Deployment
metadata:
name: legacy-app-rehosted
spec:
replicas: 3
selector:
matchLabels:
app: legacy-app
template:
metadata:
labels:
app: legacy-app
spec:
containers:
- name: app
image: myregistry/legacy-app:v1.0
ports:
- containerPort: 80
EOF
Benefits:
Fastest migration path
Minimal risk and disruption
Immediate cloud benefits (scaling, reliability)
Good starting point for further optimization
Best for:
Legacy applications
Quick cloud adoption
Proof of concept migrations
Applications with minimal changes needed
2. Replatform (Lift, Tinker, and Shift)
What it means: Make a few cloud optimizations without changing core architecture
Before (On-premises):
┌─────────────────────────────────────┐
│ Application Server │
│ ├─ Self-managed database │
│ ├─ File storage on local disk │
│ └─ Manual backups │
└─────────────────────────────────────┘
│ (Replatform)
▼
┌─────────────────────────────────────┐
│ Cloud Application │
│ ├─ Managed cloud database (RDS/SQL) │
│ ├─ Cloud object storage (S3/Blob) │
│ └─ Automated backups │
└─────────────────────────────────────┘
Container Replatform Example:
# Original: Single container with embedded database
apiVersion: apps/v1
kind: Deployment
metadata:
name: monolith-app
spec:
template:
spec:
containers:
- name: app
image: myapp:v1.0
env:
- name: DB_HOST
value: "localhost" # Embedded database
---
# Replatformed: Use cloud managed database
apiVersion: apps/v1
kind: Deployment
metadata:
name: replatformed-app
spec:
template:
spec:
containers:
- name: app
image: myapp:v1.1 # Minor changes for cloud DB
env:
- name: DB_HOST
value: "my-cluster.cluster-xyz.us-west-2.rds.amazonaws.com"
- name: DB_USER
valueFrom:
secretKeyRef:
name: db-credentials
key: username
- name: DB_PASSWORD
valueFrom:
secretKeyRef:
name: db-credentials
key: password
Cloud Services to Adopt:
Replace Self-Managed → Use Cloud Managed
┌─────────────────────────────────────┐
│ Database servers │ → RDS, Azure SQL, Cloud SQL
│ File servers │ → S3, Blob Storage, Cloud Storage
│ Message queues │ → SQS, Service Bus, Pub/Sub
│ Caching servers │ → ElastiCache, Redis, Memorystore
│ Load balancers │ → ALB, Azure LB, Cloud Load Balancing
│ Monitoring systems │ → CloudWatch, Azure Monitor, Cloud Monitoring
└─────────────────────────────────────┘
Benefits:
Reduced operational overhead
Better reliability and security
Cost optimization through managed services
Foundation for further modernization
3. Refactor (Re-architect)
What it means: Redesign applications to be cloud-native
Before (Monolith):
┌─────────────────────────────────────┐
│ Single Large Application │
│ ├─ User Management │
│ ├─ Product Catalog │
│ ├─ Order Processing │
│ ├─ Payment System │
│ └─ Notifications │
└─────────────────────────────────────┘
│ (Refactor)
▼
┌─────────────────────────────────────┐
│ Microservices Architecture │
│ ┌─────────┐ ┌─────────┐ ┌─────────┐ │
│ │ User │ │Product │ │ Order │ │
│ │ Service │ │Catalog │ │Processing│ │
│ └─────────┘ └─────────┘ └─────────┘ │
│ ┌─────────┐ ┌─────────────────────┐ │
│ │Payment │ │ Notifications │ │
│ │Service │ │ Service │ │
│ └─────────┘ └─────────────────────┘ │
└─────────────────────────────────────┘
Microservices with Kubernetes:
# User Service
apiVersion: apps/v1
kind: Deployment
metadata:
name: user-service
spec:
replicas: 3
template:
spec:
containers:
- name: user-service
image: myapp/user-service:v2.0
ports:
- containerPort: 8080
env:
- name: DATABASE_URL
value: "postgresql://user-db:5432/users"
---
# Product Catalog Service
apiVersion: apps/v1
kind: Deployment
metadata:
name: catalog-service
spec:
replicas: 5 # Can scale independently
template:
spec:
containers:
- name: catalog-service
image: myapp/catalog-service:v2.0
ports:
- containerPort: 8080
env:
- name: CACHE_URL
value: "redis://catalog-cache:6379"
Cloud-Native Patterns to Adopt:
Traditional Patterns → Cloud-Native Patterns
┌─────────────────────────────────────┐
│ Scheduled cron jobs │ → Serverless functions (Lambda, Cloud Functions)
│ Background workers │ → Event-driven processing (SQS, Pub/Sub)
│ Session storage │ → Stateless with external state (Redis)
│ File uploads │ → Direct-to-cloud storage (S3, Blob)
│ Email sending │ → Cloud email services (SES, SendGrid)
│ Log files │ → Centralized logging (CloudWatch, Stackdriver)
└─────────────────────────────────────┘
Benefits:
Maximum cloud benefits
Better scalability and resilience
Faster feature development
Cost optimization through auto-scaling
4. Retire (Turn Off)
What it means: Shut down applications that are no longer needed
Application Portfolio Analysis:
┌─────────────────────────────────────┐
│ Legacy System A │ → Active users: 5, Usage: Low
│ Legacy System B │ → Duplicate functionality
│ Legacy System C │ → Regulatory requirement ended
│ Legacy System D │ → Replaced by SaaS solution
└─────────────────────────────────────┘
│ (Retire)
▼
┌─────────────────────────────────────┐
│ Cost Savings: $50,000/year │
│ Reduced complexity │
│ Security risk reduction │
│ Focus on valuable systems │
└─────────────────────────────────────┘
Smart Retirement Process:
# 1. Identify retirement candidates
kubectl get deployments --all-namespaces
kubectl top pods --all-namespaces # Check resource usage
# 2. Analyze usage patterns
# Check application logs and metrics
# 3. Graceful shutdown
kubectl scale deployment legacy-app --replicas=0
# Monitor for any issues
# 4. Data archival
kubectl create job data-export --image=data-exporter:latest
# 5. Complete removal
kubectl delete deployment legacy-app
kubectl delete service legacy-app
Benefits:
Immediate cost reduction
Reduced security surface
Simplified architecture
Focus resources on valuable systems
5. Retain (Keep as is)
What it means: Keep applications on-premises for specific reasons
Valid Reasons to Retain:
- Regulatory requirements (data locality)
- High-performance computing needs
- Legacy systems too risky to move
- Very low usage (not worth migrating)
- Pending retirement in near future
- Custom hardware dependencies
Hybrid Architecture:
# Cloud application connecting to on-premises
apiVersion: apps/v1
kind: Deployment
metadata:
name: hybrid-app
spec:
template:
spec:
containers:
- name: web-app
image: myapp/web:v3.0
env:
- name: LEGACY_SYSTEM_URL
value: "https://onprem.company.com/api"
- name: CLOUD_DB_URL
value: "postgresql://cloud-db:5432/myapp"
Benefits: - Reduced migration risk - Compliance maintenance - Cost control for low-value systems - Gradual migration approach
6. Repurchase (Buy New)
What it means: Replace with cloud-native or SaaS solutions
Replace Custom Solutions → Use SaaS/Cloud Services
┌─────────────────────────────────────┐
│ Custom email server │ → Google Workspace, Office 365
│ Custom CRM system │ → Salesforce, HubSpot
│ Custom monitoring │ → DataDog, New Relic
│ Custom CI/CD system │ → GitHub Actions, GitLab CI
│ Custom backup solution │ → Cloud backup services
└─────────────────────────────────────┘
Integration with Containers:
# Your application integrating with SaaS
apiVersion: apps/v1
kind: Deployment
metadata:
name: modern-app
spec:
template:
spec:
containers:
- name: app
image: myapp:v4.0
env:
# Use SaaS services instead of self-hosted
- name: EMAIL_SERVICE_URL
value: "https://api.sendgrid.com/v3"
- name: CRM_API_URL
value: "https://api.salesforce.com"
- name: MONITORING_ENDPOINT
value: "https://api.datadoghq.com"
Benefits:
Reduced maintenance overhead
Professional support and SLAs
Regular feature updates
Better security and compliance
Migration Strategy Framework
Phase-Based Approach:
Phase 1: Foundation (Months 1-3)
┌─────────────────────────────────────┐
│ Set up cloud accounts and billing │
│ Establish network connectivity │
│ Migrate development environments │
│ Train team on cloud basics │
│ Containerize applications locally │
└─────────────────────────────────────┘
Phase 2: Quick Wins (Months 3-6)
┌─────────────────────────────────────┐
│ Rehost non-critical applications │
│ Migrate test environments │
│ Set up monitoring and logging │
│ Implement backup strategies │
│ Deploy containers to cloud │
└─────────────────────────────────────┘
Phase 3: Core Systems (Months 6-12)
┌─────────────────────────────────────┐
│ Replatform key applications │
│ Migrate production databases │
│ Implement auto-scaling │
│ Optimize costs and performance │
│ Establish CI/CD pipelines │
└─────────────────────────────────────┘
Phase 4: Optimization (Months 12+)
┌─────────────────────────────────────┐
│ Refactor to microservices │
│ Implement serverless functions │
│ Advanced security and compliance │
│ Multi-region deployments │
│ Cloud-native architecture │
└─────────────────────────────────────┘
Container-First Migration Benefits
Why Start with Containers:
Traditional Migration Challenges:
- "Works on my machine" syndrome
- Environment configuration drift
- Complex application dependencies
- Difficult rollbacks
- Vendor lock-in concerns
Container-First Advantages:
+ Consistent environments everywhere
+ Simplified dependency management
+ Easy rollbacks and blue-green deployments
+ Cloud portability (avoid lock-in)
+ Kubernetes works on all clouds
Migration Workflow with Containers:
# 1. Containerize locally
docker build -t myapp:v1.0 .
docker run -p 8080:8080 myapp:v1.0
# 2. Test with docker-compose
docker-compose up -d
# Validate functionality
# 3. Deploy to local Kubernetes
kubectl apply -f k8s/
kubectl port-forward service/myapp 8080:80
# 4. Push to cloud registry
docker push myregistry.azurecr.io/myapp:v1.0
# 5. Deploy to cloud Kubernetes
kubectl apply -f k8s/
kubectl get pods # Same commands work everywhere!
Risk Management and Rollback
Migration Risk Mitigation:
# Blue-Green Deployment for Safe Migration
apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
name: safe-migration
spec:
replicas: 5
strategy:
blueGreen:
activeService: myapp-active
previewService: myapp-preview
autoPromotionEnabled: false # Manual approval
scaleDownDelaySeconds: 30
prePromotionAnalysis:
templates:
- templateName: success-rate
args:
- name: service-name
value: myapp-preview
template:
spec:
containers:
- name: myapp
image: myapp:v2.0 # New cloud-optimized version
Rollback Strategy:
# Always have a rollback plan
# 1. Tag known good versions
docker tag myapp:v1.0 myapp:stable
# 2. Quick rollback capability
kubectl rollout undo deployment/myapp
# 3. Database migration rollback scripts
kubectl create configmap rollback-scripts \
--from-file=rollback.sql
# 4. Monitor key metrics during migration
kubectl apply -f monitoring/alerts.yaml
Cost Optimization During Migration
Smart Cost Management:
Development Environment Cost Optimization:
┌─────────────────────────────────────┐
│ Auto-shutdown non-production │
│ ├─ Weekends: Scale to 0 │
│ ├─ Nights: Scale down 50% │
│ └─ Use spot/preemptible instances │
├─────────────────────────────────────┤
│ Right-size resources │
│ ├─ Start small, scale up if needed │
│ ├─ Monitor actual usage patterns │
│ └─ Use horizontal pod autoscaling │
├─────────────────────────────────────┤
│ Use cloud-native services │
│ ├─ Managed databases │
│ ├─ Serverless for batch jobs │
│ └─ Object storage for static files │
└─────────────────────────────────────┘
Note
Container Advantage in Migration:
Your containerization skills make cloud migration much easier:
Portability: Same containers work on any cloud
Consistency: No “works on my machine” problems
Rollback: Easy to revert to previous versions
Testing: Identical environments for dev/test/prod
Skills Transfer: Kubernetes knowledge applies everywhere
Start containerizing NOW, even before choosing your cloud provider!