For many businesses, the cloud is no longer an optional upgrade but a strategic necessity. Scalability, cost efficiency, security and availability — the advantages are compelling. Yet the path from existing on-premise systems to the cloud requires careful planning. In this article, we show you how to carry out a cloud migration step by step.
Why Migrate to the Cloud?
Before you start, you should clearly define the reasons for migration. The most common motivations are: cost reduction by eliminating proprietary server hardware and maintenance, better scalability during peak loads, higher availability through global data centers, improved security through professional infrastructure and faster deployment of new services.
Not every system benefits equally from migration. Legacy applications tightly coupled to specific hardware may require extensive modifications. An honest cost-benefit analysis at the outset saves surprises later.
The 6 Migration Strategies (6 Rs)
AWS popularized the six common migration strategies that have become an industry standard:
Rehosting (Lift & Shift): The application is moved to the cloud one-to-one — with no code changes. Quick to implement, but not always cost-efficient since cloud-optimized advantages remain unused.
Replatforming (Lift & Optimize): Minor adjustments to leverage cloud services — such as switching from a self-managed database to a managed service like Amazon RDS or Azure SQL.
Refactoring (Re-Architecting): The application is redesigned for the cloud — for example, as a microservices architecture with containers. Highest effort, but also the greatest optimization potential.
Repurchasing: Switching to a SaaS solution. Example: a self-hosted email server is replaced by Microsoft 365.
Retaining: Certain systems remain on-premise for the time being — for instance because migration is too complex or not economically viable.
Retiring: Systems that are no longer needed are shut down. Often, an inventory reveals 10 to 20 percent of systems as redundant.
Step 1: Inventory and Assessment
Capture all existing systems, dependencies and data flows. Which servers are running? Which applications are installed on them? How do the systems communicate with each other? Tools like AWS Application Discovery Service or Azure Migrate can support this process.
Also document non-technical factors: compliance requirements, data protection regulations (particularly relevant for GDPR), SLA requirements and licensing models that may change in the cloud.
Step 2: Strategy and Prioritization
Not everything needs to be migrated at once. Prioritize by business value and migration effort. Start with non-critical systems to gain experience, then work your way up to business-critical applications. A typical migration timeline for a mid-sized company ranges from three to twelve months.
Step 3: Containerization
Docker and Kubernetes are the de facto standards for containerizing applications. Containers make your applications portable, reproducible and scalable. The process includes: creating Dockerfiles that define your application and its dependencies, setting up a container registry, configuring Kubernetes clusters (or using managed services like EKS, AKS or GKE) and defining deployment manifests.
Not every application needs to be containerized. For simple workloads, serverless services like AWS Lambda or Azure Functions may be the better choice.
Step 4: Build a CI/CD Pipeline
An automated CI/CD pipeline is the backbone of modern cloud deployments. It ensures that code changes are automatically tested, built and deployed. Common tools include GitHub Actions, GitLab CI, Jenkins or AWS CodePipeline. A typical pipeline comprises: code commit, automated tests, container build, security scan, staging deployment, manual approval and production deployment.
Step 5: Infrastructure as Code (IaC)
Define your entire cloud infrastructure as code — using Terraform, Pulumi or AWS CloudFormation. This brings versioning, reproducibility and consistency to your infrastructure. Changes are reviewed via pull requests and can be quickly rolled back if problems arise.
Step 6: Execute the Migration
The actual migration should be planned and carried out in waves. Start with a test run in a staging environment. Define clear rollback strategies in case something goes wrong. Communicate planned downtime to all stakeholders in advance. And monitor all systems closely after the migration.
Step 7: Optimization and Monitoring
After migration, the optimization phase begins. Set up comprehensive monitoring — with tools like Prometheus, Grafana, Datadog or native cloud monitoring services. Analyze your costs regularly and use Reserved Instances or Spot Instances to reduce spending. Implement auto-scaling so your infrastructure automatically adapts to load.
Avoiding Common Mistakes
No cost control: Cloud costs can spiral quickly if no budgets and alerts are set up. Use cost management tools from the start.
Neglecting security: The cloud is not automatically secure. Implement zero-trust principles, encryption and regular audits.
Big-bang migration: Migrating everything at once is risky. Proceed iteratively and learn from each step.
Conclusion
A cloud migration is a project that requires careful planning, technical expertise and a clear roadmap. Done right, it brings significant advantages in terms of cost, scalability and speed of innovation. The most important advice: start with a plan, proceed step by step and invest in the right foundations — containerization, CI/CD and Infrastructure as Code.