Preparing Universal Credit for post Brexit arrangements

Devops, Cloud migration

The Problem

In 2019/20, the UK grappled with the implications of Brexit for departments housing data in the EU. The Universal Credit application resided in AWS Ireland, predating the availability of the London region. A decision was made to migrate the service across regions. Universal Credit stored over 400 terabytes of data across various locations, requiring migration with minimal downtime due to its critical importance.

 The Solution

With a deep understanding of the application, engineers rewrote both the application and infrastructure code to rebuild it in London. This would dual run as one huge application before a final two hour switch over.. This demanded expertise across applications, networking, databases, messaging, AWS, and infrastructure. Data synchronization ensured data remained current until the final cutover. On migration evening, we executed final automated cutover run books to switch service ingress, directing traffic solely to London. Prior practice in lower environments boosted confidence for both ourselves and the business.

The Results

The migration not only encompassed the application but also migrated all supporting tools, including logging, monitoring, and audit data. We monitored results for two weeks post-cutover, promptly addressing any arising issues. Subsequently, we commenced decommissioning the old application and addressing technical debt. The client expressed satisfaction with the results, enabling them to mitigate perceived risks before the January 2021 deadline.