Things I've actually migrated
Not hypotheticals. Over the past few years I've personally moved:
- A self-hosted Atlassian suite (Jira, Confluence, Bitbucket) to Atlassian Cloud, retiring the servers underneath it
- An entire CI/CD platform from self-hosted Bamboo to Bitbucket Pipelines and AWS CodeDeploy, service by service, without missing a release
- On-prem enterprise SFTP infrastructure to a serverless AWS build (Transfer Family, Lambda, S3) that now costs almost nothing to run
- Analytics workloads from licensed MSSQL onto Redshift Serverless
- A legacy licensed ETL platform onto modern tooling, killing the annual licence with it
How a migration runs
The method is boring on purpose. Assess what exists and what actually depends on it. Build the new thing alongside the old, as code. Run both in parallel until the numbers match. Cut over in a low-traffic window, with a rollback path ready. Decommission, and enjoy cancelling the old invoice.
The last step is my favourite part, and usually how the project pays for itself.