Cloud Migration Strategy: A Complete Guide

A cloud migration strategy defines how you move your applications, data, and infrastructure from legacy data centers or colocation facilities to the cloud. Moving workloads without a structured plan can lead to service downtime, unpredictable costs, and security vulnerabilities.

While traditionally associated with leaving physical data centers, today's migrations frequently involve moving between cloud environments. Engineering teams routinely execute cloud-to-cloud migrations to optimize infrastructure spend, guarantee European data sovereignty, and avoid proprietary vendor lock-in.

This guide covers the 7 primary cloud migration strategies, how to choose the right approach for your tech stack, a step-by-step migration process, and practical best practices for engineering teams.

What is a Cloud Migration Strategy?

A cloud migration strategy is a technical and operational roadmap for moving digital assets from local servers or existing cloud environments to a target cloud infrastructure.

It outlines how each application, database, and service will be moved, configured, and secured while minimizing service disruption and technical debt.

Why Do You Need a Cloud Migration Strategy?

Migrating infrastructure without a plan creates operational risk and cost overruns. A clearly defined strategy provides clear operational benefits:

• Reduced Business Risk and Downtime: Mapping service dependencies prior to cutover prevents unexpected outage cascades.
• Predictable Cost Control: Strategic planning right-sizes compute resources and favors cloud providers with transparent pricing and zero hidden egress bandwidth fees.
• Security and Compliance Alignment: Establishing Virtual Private Clouds (VPC), access policies, and secret management prior to data transfer ensures GDPR compliance and data protection.
• Avoidance of Vendor Lock-in: Moving unoptimized systems to the cloud simply carries legacy inefficiencies into a new environment. A strategy determines whether an application should be rehosted, rewritten, or decommissioned.

The 7 Cloud Migration Strategies (7 Rs)

The 7 Rs framework provides a proven structure for moving workloads. Selecting the right migration path for each application is essential to executing a successful cloud strategy.

1. Rehost (Lift-and-Shift)

Rehosting moves applications directly from physical servers or local virtual machines to cloud virtual instances without modifying code or application architecture. It offers the fastest migration timeline, making it suitable for legacy systems under tight deadlines, though it misses cloud-native auto-scaling capabilities.

2. Relocate

Relocating shifts hypervisor instance snapshots or instances directly to a target hosted cloud environment, without changing guest operating systems, container specs, or application logic. This strategy is primarily relevant for cloud-to-cloud or hybrid migrations, allowing organizations to move hosted infrastructure between platforms rapidly with zero re-architecture.

3. Replatform

Replatforming introduces targeted infrastructure upgrades, without rewriting core application code. A common pattern is replacing a self-hosted database VM with a managed cloud database service, reducing operational maintenance while preserving application code stability.

4. Refactor (Rearchitect)

Refactoring completely redesigns applications into cloud-native architectures, such as microservices on container management platforms like Kubernetes or event-driven serverless functions. This delivers maximum agility, horizontal elasticity, and resilience for mission-critical services.

5. Repurchase (Drop-and-Shop)

Repurchasing replaces an existing internal tool or legacy application with a cloud-hosted Software as a Service (SaaS) solution.

6. Retire

Retiring decommissions redundant applications, obsolete staging environments, or outdated data repositories that no longer add business value.

7. Retain (Revisit)

Retaining keeps specific workloads on-premise due to strict latency requirements, regulatory constraints, or unamortized hardware investments.

How to Choose the Right Cloud Migration Strategy

Choosing the right approach requires evaluating application architecture, data dependencies, and operational complexity.

Cloud Migration Strategy Planning

Planning requires setting up foundational infrastructure before transferring production data. Focus on the four following technical pillars:

1. IAM and Account Hierarchy: Implement strict role-based access control and isolation across environments.
2. Network Architecture (VPC): Define private subnets, security groups, and custom routing rules to isolate internal traffic.
3. Secret Management: Remove hardcoded credentials and inject runtime variables using dedicated secret managers.
4. Infrastructure as Code (IaC): Version-control all network resources, compute instances, and Kubernetes clusters using Terraform.

Step-by-Step Cloud Migration Process

Executing a migration involves five sequential phases:

1. Assess your current infrastructure: Catalog all physical servers, VMs, storage volumes, and existing cloud assets. Track CPU, memory, storage utilization, and network traffic patterns to size target instances accurately and estimate data transfer requirements.
2. Define migration goals: Set concrete technical targets, including acceptable cutover downtime windows, performance benchmarks, cost limits, and European data sovereignty requirements.
3. Choose the right migration approach: Assign one of the 7 Rs strategies to each workload and group services into migration waves according to their dependency graph.
4. Migrate workloads and data: Provision cloud networks, establish database replication, sync static storage, and deploy staging environments.
5. Test and optimize: Run load tests, verify database replication integrity, test failover paths, and execute DNS cutover.

Cloud Migration Best Practices

To maintain system reliability throughout the transition, follow these field-tested practices:

• Automate Everything with IaC: Declare all network rules, virtual machines, and clusters in code rather than configuring them manually.
• Use Continuous Replication: Set up continuous logical replication for databases to enable near-zero downtime cutovers.
• Decouple Application Secrets: Store credentials in Scaleway Secret Manager instead of passing environment variables in plain text.
• Establish Baseline Observability: Deploy metrics collection and logging prior to cutover to verify performance against baseline metrics.

Pro Tip: Never cut over production traffic without performing a full restoration test from snapshots in an isolated staging network.

Cloud Migration Tools and Services

Leveraging open standards prevents vendor lock-in and streamlines execution:

• Provisioning: Terraform, OpenTofu, Ansible.
• Storage and Database Sync: Rclone, native database logical replication tools, Scaleway CLI.
• Application Orchestration: Docker, Helm, Scaleway Kubernetes Kapsule.
• Secrets: Scaleway Secret Manager.

Cloud Migration Strategy Examples

Reviewing common migration scenarios helps illustrate how to apply the 7 Rs:

Scenario A: E-Commerce Platform Modernization

• Initial State: Monolithic application and MySQL database on physical servers.
• Strategy: Replatform and Refactor.
• Execution: APIs and frontend services were containerized and deployed on Scaleway Kubernetes Kapsule. MySQL was transitioned to Scaleway Managed Database for MySQL via logical replication.
• Outcome: Automatic horizontal scaling during traffic spikes and zero physical server maintenance overhead.

Scenario B: SaaS Platform Lift-and-Shift

• Initial State: Virtual machines hosting proprietary backend services.
• Strategy: Rehost (Lift-and-Shift).
• Execution: VM disk images were migrated directly to Scaleway PRO2 compute instances connected to a private VPC network.
• Outcome: Fast data center exit within 30 days and predictable monthly infrastructure costs.

Migrate to Scaleway

A structured cloud migration strategy gives your engineering team the foundation to scale efficiently without unexpected costs or vendor lock-in. Scaleway provides transparent pricing, European data sovereignty, and energy-efficient data centers to support your cloud journey.

• Build a multi-account foundation with governance and security best practices using Scaleway Landing Zone.
• Review technical tutorials and architecture guides in the Scaleway Documentation.
• Provision your target cloud resources directly in the Scaleway Console.
• Connect with DevRel engineers and technical peers on Scaleway Slack.