Migration from a US Hyperscaler to a Sovereign EU Cloud
Lift-and-reshape of 120 workloads from AWS to OpenStack-based EU infrastructure - zero downtime, 30% lower run costs, and complete data residency for a public-sector supplier.
Challenge
As a supplier to German public authorities, the client faced tender requirements that effectively excluded US-controlled cloud providers. The existing AWS estate had grown organically: 120 workloads, managed services everywhere, and no infrastructure-as-code. A naive lift-and-shift would have carried both the cost model and the lock-in into the new environment.
Approach
We started with an automated dependency mapping of all workloads and grouped them into six migration waves by criticality and coupling. Managed services were replaced one-to-one by open, operable equivalents: RDS became PostgreSQL on Patroni, S3 became Ceph object storage, SQS became RabbitMQ - all defined as Terraform modules with the same interfaces. Cutovers ran as blue-green deployments with database replication lag under five minutes. A weekly cost review compared AWS CUR data against the new environment's metering, workload by workload.
Outcome
All 120 workloads migrated in seven months with zero unplanned downtime. Run costs down 30%, full data residency in German data centers certified to ISO 27001 and BSI C5, and the client qualifies for public-sector tenders again. The Terraform codebase makes the estate portable - sovereignty without a new lock-in.