Developing a Modern Build System for the Earth System Modelling Framework MESSy

The earth system modelling framework MESSy is a large Fortran software used on high-performance computing (HPC) clusters. On these systems, software is usually built from source with dedicated configuration for each cluster. This paper describes the process of replacing the old build system based on autoconf by a modern build system based on CMake. CMake offers a higher abstraction level and better portability across HPC systems and architectures. We focus on recreating the existing configuration options and build targets (binaries, libraries) with identical compiler flags and dependencies while improving the maintainability, the usability, and the compilation time.