Kubernetes Migration

Migration planning reference for moving workloads to Kubernetes

Use this reference to plan workload migration from legacy infrastructure to Kubernetes. It covers assessment, containerization, deployment patterns, cutover planning, and post-migration validation.

Why Migrate to Kubernetes?#

Organizations migrate to Kubernetes to achieve operational excellence and business agility:

Migration approach#

Phase 1: Discovery and Assessment#

Start with a structured assessment of the current infrastructure and application estate.

Application Inventory

• Complete application portfolio mapping
• Dependency graph analysis
• Data flow documentation
• Integration point identification

Containerization Readiness

Each application should be evaluated against a readiness matrix:

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┌─────────────────────────────────────────────────────────────────┐
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│                    Readiness Assessment Matrix                   │
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├─────────────────────────────────────────────────────────────────┤
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│  Application Type     │ Complexity │ Migration Strategy          │
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├───────────────────────┼────────────┼─────────────────────────────┤
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│  Stateless services   │    Low     │ Lift and shift              │
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│  12-factor apps       │    Low     │ Direct containerization     │
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│  Stateful services    │   Medium   │ Replatform with PV/PVC      │
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│  Legacy monoliths     │    High    │ Strangler fig pattern       │
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│  Mainframe/COBOL      │  Very High │ Modernization roadmap       │
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└─────────────────────────────────────────────────────────────────┘

Deliverables

• Migration readiness report
• Application complexity scores
• Recommended migration sequence
• Risk assessment and mitigation plan
• Resource and timeline estimates

Phase 2: Containerization#

Transform your applications into container-ready workloads.

Dockerfile Development

We create optimized Dockerfiles following security and performance best practices:

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# Multi-stage build for optimal image size
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FROM node:20-alpine AS builder
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WORKDIR /app
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COPY package*.json ./
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RUN npm ci --only=production
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COPY . .
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RUN npm run build
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FROM node:20-alpine AS runtime
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RUN addgroup -g 1001 -S nodejs && \
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    adduser -S nextjs -u 1001
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WORKDIR /app
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COPY --from=builder --chown=nextjs:nodejs /app/dist ./dist
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COPY --from=builder --chown=nextjs:nodejs /app/node_modules ./node_modules
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USER nextjs
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EXPOSE 3000
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CMD ["node", "dist/server.js"]

Image Optimization

• Multi-stage builds for minimal image size
• Non-root user configuration
• Security scanning integration
• Vulnerability remediation
• Base image standardization

Registry Setup

• Private registry configuration (ECR, ACR, GCR, Harbor)
• Image signing and verification
• Automated scanning pipelines
• Retention and cleanup policies

Phase 3: Kubernetes Infrastructure#

Set up production-ready Kubernetes clusters tailored to your requirements.

Cluster Architecture

Infrastructure Components

• Node pool design and sizing
• Networking (CNI, service mesh, ingress)
• Storage classes and persistent volumes
• Security policies and RBAC
• Secrets management integration
• Observability stack deployment

Phase 4: Workload Migration#

Execute the migration with zero-downtime strategies.

Migration Strategies

Helm Chart Development

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# values.yaml - Environment-specific configuration
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replicaCount: 3
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image:
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  repository: registry.example.com/app
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  tag: v1.0.0
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  pullPolicy: IfNotPresent
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resources:
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  requests:
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    cpu: 100m
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    memory: 128Mi
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  limits:
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    cpu: 500m
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    memory: 512Mi
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autoscaling:
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  enabled: true
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  minReplicas: 3
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  maxReplicas: 10
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  targetCPUUtilization: 70
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ingress:
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  enabled: true
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  className: nginx
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  annotations:
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    cert-manager.io/cluster-issuer: letsencrypt-prod
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  hosts:
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    - host: app.example.com
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      paths:
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        - path: /
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          pathType: Prefix

Data Migration

• Database migration strategies
• Stateful workload handling
• Data synchronization during cutover
• Rollback procedures

Phase 5: Validation and Optimization#

Ensure your migrated workloads perform optimally.

Performance Validation

• Load testing in Kubernetes environment
• Latency and throughput benchmarking
• Resource utilization analysis
• Cost optimization recommendations

Operational Readiness

• Runbook development
• Incident response procedures
• Monitoring and alerting setup
• Team training and knowledge transfer

Migration Patterns#

Lift and Shift#

Containerize applications with minimal changes for quick wins.

Best for:

• Stateless applications
• Applications with clear boundaries
• Time-sensitive migrations
• Applications scheduled for future refactoring

Process:

1. Create Dockerfile for existing application
2. Configure external dependencies (databases, caches)
3. Deploy to Kubernetes with basic manifests
4. Validate functionality
5. Cutover traffic

Replatform#

Optimize applications for Kubernetes while migrating.

Best for:

• Applications benefiting from Kubernetes features
• Workloads requiring horizontal scaling
• Services needing improved observability
• Applications with technical debt to address

Enhancements:

• Externalize configuration to ConfigMaps/Secrets
• Implement health checks (liveness, readiness, startup)
• Add structured logging
• Configure resource requests and limits
• Enable horizontal pod autoscaling

Strangler Fig Pattern#

Incrementally migrate monolithic applications.

Best for:

• Large monolithic applications
• Applications with tightly coupled components
• High-risk migrations requiring gradual approach
• Systems requiring continuous availability

Process:

1. Identify bounded contexts within monolith
2. Extract services incrementally
3. Route traffic through API gateway
4. Migrate functionality piece by piece
5. Decommission monolith when complete

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┌─────────────────────────────────────────────────────────────────┐
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│                    Strangler Fig Migration                       │
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│                                                                  │
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│  ┌──────────┐     ┌──────────┐     ┌──────────┐                │
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│  │ Monolith │ ──► │ Facade + │ ──► │ Micro-   │                │
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│  │          │     │ Services │     │ services │                │
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│  └──────────┘     └──────────┘     └──────────┘                │
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│                                                                  │
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│  Phase 1:          Phase 2:         Phase 3:                    │
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│  Identify          Extract          Complete                    │
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│  boundaries        services         migration                   │
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└─────────────────────────────────────────────────────────────────┘

Common Challenges and Solutions#

Stateful Applications#

Challenge: Migrating applications with persistent data requirements.

Solutions:

• Use StatefulSets for ordered, stable pod identity
• Configure appropriate storage classes (SSD, HDD, network-attached)
• Implement proper backup and restore procedures
• Consider managed databases for reduced operational burden

Service Discovery#

Challenge: Applications hardcoded with IP addresses or hostnames.

Solutions:

• Use Kubernetes DNS for service discovery
• Implement service mesh for advanced routing
• Configure external-dns for external access
• Use headless services for direct pod access when needed

Secrets Management#

Challenge: Securely managing credentials and sensitive configuration.

Solutions:

• Integrate with external secrets managers (Vault, AWS Secrets Manager)
• Use sealed-secrets for GitOps workflows
• Implement proper RBAC for secret access
• Rotate secrets automatically

Network Policies#

Challenge: Implementing network segmentation in Kubernetes.

Solutions:

• Define NetworkPolicies for micro-segmentation
• Use Calico or Cilium for advanced networking
• Implement service mesh for mTLS
• Configure egress controls for compliance

Migration readiness checklist#

• Application inventory and dependency graph are current.
• Stateful components have backup, restore, and data-migration plans.
• Container images have ownership, patching, and vulnerability-scanning expectations.
• Kubernetes manifests or Helm charts are reviewed in lower environments before production.
• Rollback, traffic shifting, and observability requirements are documented before cutover.
• Post-migration validation includes performance, availability, cost, and operational handoff checks.

Related Resources#

• Kubernetes Migration Case Study - How MegaCorp migrated 200+ applications
• Kubernetes introduction
• GitOps reference
• ArgoCD for Continuous Delivery
• Docker Introduction