The Department for Work and Pensions (DWP) has completed the migration of part of the Universal Credit system to run on the Amazon Web Services (AWS) public cloud.

The Universal Credit (UC) digital service – now known as UC Full Service – is currently being rolled out across UK Jobcentres, where it is replacing the so-called Pathfinder system that supported the original implementation of a limited version of the controversial new benefits system.

Unlike Pathfinder, the digital service was designed for the cloud, and first moved into a cloud environment when the system was being trialled in south London in 2015.

UC Full Service completed its move to AWS during the summer, according to John Keegan, head of cloud infrastructure services at DWP Digital, speaking at a recent government IT conference.

Use of AWS is part of DWP’s hybrid cloud strategy, which sees Universal Credit developed as a series of microservices, some of which run in-house and others in the cloud.

“UC Full Service is a collection of more than 20 loosely coupled products, not all of which are built by DWP,” said Mayank Prakash, chief digital and information officer at DWP, in written answers to questions submitted to DWP by Computer Weekly.

“DWP has moved from building system silos to designing for integrated user experiences, re-using microservices and implementing RESTful APIs [application programming interfaces] to integrate data and services – for example, integration with banks to transfer payments into customer accounts,” he said.

“DWP uses hybrid cloud platforms to host our services at a fraction of the cost of how we were doing it before. This provides more flexibility, faster delivery and increased control. We prefer using commodity cloud infrastructure, virtualisation and containerisation.”

Read more about AWS in government Why the public cloud will revolutionise government IT.

AWS caters to public sector users with its GovCloud region, which includes stricter compliance standards. But how popular is the region – and AWS – among government agencies?

AWS claims UK region opening will help existing customers meet their latency and data sovereignty requirements, and benefit the wider economy.

Prakash said DWP also works with Microsoft’s Azure cloud offerings, but did not respond to a question asking which parts of Universal Credit run on Amazon. He stressed that “robust controls around security and data protection” are in place to ensure appropriate data governance.

Use of AWS and Azure is part of DWP’s cloud-first policy, which aims to avoid lock-in to any one platform or provider.

“Large enterprises like DWP operate a multi-platform environment with diverse operating systems and rarely move to any one provider for all hosting needs. DWP’s hybrid cloud strategy is deliberate to deliver private and public cloud services,” said Prakash.

“This enables the department to assure both data privacy and deploy elastic expansion on demand. Crucially, public cloud platforms also unlock access to innovative products and services in a competitive market.”

The move to cloud has also been supported by the introduction of agile methods and the use of DevOps practices.

“The main challenge with using large-scale agile development practices is that continuous integration and test automation implementation is complex. This requires large enterprises to use consistent methods for scaling up across the enterprise. The secondary challenge is balancing a DevOps culture with reliability of live production services,” said Prakash.

“The key lesson is that it is important to balance iterative design of infrastructure as code with structured delivery of components to reduce the risk of technical issues and validate the design. There’s no substitute for a good design supported by well-structured delivery and migration – taking a full stack view is crucial to doing this well.”

AWS is also being used at HM Revenue & Customs, which migrated part of its new digital tax system to Amazon earlier this year.

Some critics have attacked the government for its apparent enthusiasm for AWS at a time when Amazon is being accused of not paying enough tax in the UK.