MCUd is a framework for running D on microcontrollers (or MCUs). It provides a declarative style of programming allowing one to create complex embedded firmwares in a higly maintable manner.
In addition, it aims to reduce flash memory usage as much as possible and make the entire user application (and even MCUd itself) fully unit-testable.
As very few vendors or distributions ship compilers with support for D, all compile jobs run in Docker containers containing the right tools needed to build MCUd for your target CPU.