A Practical Guide to Migrating Legacy Apps to the Cloud

Migrating a legacy application to the cloud rarely works well as a single "big bang" cutover. We favor a phased approach:

1. Assess & inventory

Map every dependency, data store and integration point before writing a migration plan.

2. Rehost, then refactor

Get the application running in the cloud first (lift-and-shift), then incrementally refactor toward cloud-native patterns like managed databases and autoscaling.

3. Validate with shadow traffic

Run the new environment alongside the old one, comparing outputs before fully cutting over.

4. Cut over with a rollback plan

Every migration should have a tested rollback path, no matter how confident the team is.

Done well, this approach minimizes downtime and gives stakeholders confidence at each stage rather than one high-stakes cutover night.