Skip to main content

Cloud Migration Strategies

Updated Oct 03, 2022 ·

Overview​

Cloud migration can follow different strategies depending on business goals, technical requirements, and constraints. Each approach has its own benefits and use cases.

  • Rehost (Lift and Shift)

    • Move servers or applications from on-premise directly to the cloud.
    • Quick migration with minimal changes.
    • Scalable and pay-as-you-go.
    • Ideal for organizations starting migration or with tight deadlines.

  • Replatform (Modify Lift and Shift)

    • Make small optimizations during migration.
    • Improves efficiency without full redesign.
    • Enhances performance for specific workloads.
    • Reduces long-term maintenance costs.

  • Repurchase (Drop and Shop)

    • Switch to a different product or service
    • Often changing licensing or platform.
    • Moves away from incompatible software.
    • Can reduce licensing complexity.

  • Refactor (Rearchitect)

    • Redesign the application to be cloud-native.
    • Improves availability and reliability.
    • Enables better scalability and flexibility.

  • Retain (Hybrid or Partial Migration)

    • Keep some systems on-premise due to readiness or regulations.
    • Supports phased migration.
    • Ensures compliance with legal or corporate policies.

  • Retire (Turn Off Services)

    • Identify and shut down unused or low-value services.
    • Reduces costs and operational complexity.
    • Focuses resources on key business areas.

Strangler Fig Pattern​

The Strangler Fig pattern helps migrate large legacy applications incrementally to the cloud. Instead of rewriting everything at once, you modernize one function at a time.

  • Modernize one feature as a microservice
  • Host the new microservice in the cloud
  • Remove the same feature from the legacy app
  • Repeat until the entire application is re-architected

Example: Banking Application Modernization​

A bank can apply the Strangler Fig pattern to move its online banking app to the cloud without disrupting operations.

  1. Start with the digital wallet

    • Develop it as a containerized microservice
    • Deploy it on Google Kubernetes Engine (GKE)
    • Replace the legacy wallet once functional

  2. Capture wallet transactions with Google Cloud Spanner

    • Gain scalability and concurrent transaction handling
    • Replace the old legacy functionality

  3. Add a financial dashboard

    • Build using Google BigQuery and Looker
    • Replace the legacy dashboard gradually

  4. Repeat for other core functions

    • Incrementally modernizes the entire banking app
    • Minimal disruption to ongoing operations

This pattern ensures that large applications can be modernized step by step, improving scalability and performance while keeping operations stable throughout the migration.

Resources​