The Government Digital Service (GDS) has revealed that the beta version of the GOV.UK single domain website is currently hosted on Amazon Web Services (AWS).
However, the organisation, which sits in the Cabinet Office, is only using services from AWS that can be easily migrated to other suppliers. It plans to switch to relevant services in the G-Cloud framework once they are up and running.
"The key design rule is not to be locked into a single supplier and to make it trivial to swap hosting partners," James Stewart, a technical architect at the GDS, wrote on a blog.
Stewart said that GDS chose Amazon because it met its short-term needs of stability, high quality tools that could be easily integrated into its scripts and "excellent" technical support.
"Without access to cloud hosting with the flexibility such as is provided by AWS we'd not have been able to develop the beta with nearly as much freedom," Stewart said.
In the future, however, GDS may consider using a hybrid hosting environment, comprising of AWS, other cloud platforms and traditional on-premise hardware.
GDS is primarily developing with the open source programming language Ruby, using a mixture of Ruby on Rails and Sinatra. One of its applications is written in Scala because it needs to be able to handle a high level of concurrency.
In terms of databases, the organisation uses MySQL for developing, and hands over the responsibility for database scaling to Amazon when it deploys them.
By using Amazon's Relational Database Service (RDS), Stewart said that this can be done without any changes being made to the code.
"That means that if we were to later decide to move that code to another hosting environment we would be able to focus on moving the data, and not have to spend time rebuilding our apps too," he said.
While choosing to use Amazon's RDS was an easy decision, Stewart admits that GDS was more cautious about using AWS's email service.
"Some quirks" in how the email service handled standard email protocols meant that GDS developers had to add specific code to interface with it.
The organisation only decided to go ahead with the email service once it was convinced that switching away from it would be straightforward.
GDS said that it has maintained an agile, iterative approach throughout the development of the single domain website, which GDS director Mike Bracken has previously declared is the way the UK government will work digitally in the future.