envs

Environment Definitions

The environments use Spack for binary dependencies where we want to compile with different compilers and MPIs, and Mamba for Python dependencies where we want to make use of packages on conda-forge.

The Spack and Mamba environments are somewhat integrated - Spack is set up to use the Mamba environment as its Python implementation.

Environment Contents

Environment definitions are stored as directories under envs/. Each directory should at least container a spack.yaml file.

• spack.yaml: Spack environment configuration
• mamba.yaml: Conda environment configuration
• env.activate.sh: Extra environment variable settings, sourced when the environment is activated
• post-install.sh: Extra install steps, run when the container is created after the Spack and Conda environments are created

Variants

The variants/ directory in each environment contains the different pre-requisites we want to build the environment with. These are Spack environment configuration files that get merged with the main spack.yaml file.

For example, lfric-v0/variants/gcc-openmpi.yaml looks like

spack:
    packages:
        all:
            require: "%gcc@8.5.0"
        mpi:
            require: "openmpi@4.1.4"

These configurations are merged with lfric-v0/spack.yaml to create the lfric-v0/gcc-openmpi container environment.

Adding new packages

To add a new package to an environment add its name to either the spack.yaml or mamba.yaml file. Generally Python packages should go into mamba.yaml and everything else into spack.yaml. You can check what packages are available at https://conda-forge.org/packages/ or https://packages.spack.io/.

Adding new environments

To create a new environment make a new directory under envs/ with at least a spack.yaml file, see the existing environment definitions for ideas.