Implementation of FAB in Momentum Simulation Systems

The Met Office is preparing an important change in managing their software stack, migrating from the old Subversion-based versioning system to the modern Git. Besides required changed to all existing suites, there is also a need to replace the outdated build tool called FCM: FCM does not support git, has shortcoming in supporting LFRic, and is written in a language that is not well-supported by Met Office developers anymore. 6 years ago, the Met Office decided to implement a new, modern build system called Fab that addresses the shortcoming of FCM. While there was an initial, proof-of-concept release, with the help of the Bureau of Meteorology (BoM) Fab was extended to support missing features, and it was shown to be well-suited to build LFRic-based applications. This work will involve close collaboration with the Git migration team to develop Fab scripts tailored for repositories as they transition to Git. These scripts will serve as reusable templates for other sites within the Momentum Partnership, enabling them to efficiently port their own repositories. Additionally, BoM may introduce new features to Fab to accommodate specific requirements from various suites.