Quick Start for Developers

Unix Shell

Currently, compass only supports bash and related unix shells (such as ksh on the Mac). We do not support csh, tcsh or other variants of csh. An activation script for those shells will not be created.

If you normally use csh, tcsh or similar, you will need to temporarily switch to bash by calling /bin/bash each time you want to use compass.

Set up a compass repository: for beginners

To begin, obtain the main branch of the compass repository with:

git clone git@github.com:MPAS-Dev/compass.git
cd compass
git submodule update --init --recursive

The E3SM repository and a clone of E3SM for MALI development are submodules of the compass repository.

compass pixi and Spack environments, compilers and system modules

As a developer, you will need your own deployment environment with the latest dependencies for compass and a development installation of compass from the branch you’re working on.

Compass now uses mache.deploy for deployment. In this repository, the entry point is ./deploy.py.

You will typically rerun ./deploy.py each time you check out a new branch or create a new worktree with git. In most cases, you do not need to rerun deployment while you are editing existing files in the compass package because compass is installed in editable mode.

Note

./deploy.py expects pixi to be available either on PATH or at ~/.pixi/bin/pixi. If your pixi executable lives somewhere else, pass it explicitly with --pixi <path>.

Supported machines

If you are on one of the Supported Machines, run:

./deploy.py [--machine <machine>] [--compiler <compiler> ...] \
    [--mpi <mpi> ...] [--deploy-spack] [--no-spack] \
    [--pixi-path <path>] [--recreate] [--with-albany]

If you are on a login node, machine detection typically works automatically. You can pass --machine <machine> explicitly if needed.

By default, Compass will reuse existing machine-specific Spack environments when the current deployment needs them. On supported machines, this now means per-toolchain library environments together with a shared software environment for tool binaries such as ESMF and MOAB. Use --deploy-spack when you want to build or update those Spack environments. Use --no-spack for a pixi-only deployment.

Environments with Albany

If you are working with MALI, use --with-albany so the Albany and Trilinos libraries are included in the deployed Spack library environment. Albany is currently only supported for some machine/compiler/MPI combinations, most commonly gnu builds on supported machines.

Unknown machines

If a machine is not known to mache, add machine support first (see Adding a New Supported Machine).

For workflows that need custom machine config files, see Config Files.

What the script does

./deploy.py can:

create or update a local pixi deployment prefix (pixi-env by default)
install Jigsaw and Jigsaw-Python from the jigsaw-python submodule when needed
install the compass package from the local branch in editable mode so changes you make to the repo are reflected immediately
optionally deploy or reuse Spack library environments for selected compiler/MPI toolchains, plus a shared Spack software environment for supporting binaries
generate activation scripts (load_*.sh)

Useful flags

--machine: Set the machine explicitly instead of relying on automatic detection
--pixi-path: Choose the directory for the pixi environment (pixi-env in the repository root by default). --prefix is a deprecated alias.
--compiler, --mpi: Select compiler/MPI combinations, primarily for Spack deployment
--deploy-spack: Deploy supported Spack library/software environments instead of only reusing existing ones
--no-spack: Disable all Spack use for this run and rely on pixi dependencies instead
--spack-path: Set the Spack checkout path used for deployment
--recreate: Recreate deployment artifacts if they already exist
--bootstrap-only: Update only the bootstrap pixi environment used internally by deployment
--mache-fork, --mache-branch, --mache-version: Test deployment against a specific mache fork, branch or version

Activating the environment

Each time you want to work with compass, source one of the generated load scripts:

source ./load_*.sh

On supported machines, the scripts are named load_compass_<machine>_<compiler>_<mpi>.sh, one for each compiler and MPI combination you deployed. Sourcing a load script checks that the compass package in the pixi environment is the version the script was generated for, activates the pixi environment, loads machine modules and Spack environments when appropriate, and sets environment variables needed by compass and MPAS components.

When you are working inside a suite or test-case work directory, source load_compass_env.sh instead. This is a symlink to the load script you used while setting up the work directory.

The active load script path is exported in COMPASS_LOAD_SCRIPT. Compass still accepts LOAD_COMPASS_ENV as a legacy fallback while the migration is in progress.

If you wish to work with another compiler or MPI library, rerun ./deploy.py with the desired options so the corresponding load script is generated or refreshed. Make sure you build MPAS with the same compiler and MPI combination as the load script you plan to use.

Switching between different compass environments

./deploy.py installs the compass package in editable mode from the directory where you run it. Changes you make to existing files, and files you add or remove, are picked up without redeploying or re-sourcing the load script. The pixi environment and load scripts do have to be updated when the compass version or its dependencies change.

Many developers switch between compass branches, either by checking out different branches in the same directory (with git checkout) or by creating a directory for each branch (with git worktree).

If you switch branches in the same directory, the editable install follows the checkout, so there is nothing to do as long as the compass version and dependencies are the same. If the version has changed, the load script refuses to activate the environment with an error like:

$ source load_compass_chrysalis_gnu_openmpi.sh
verifying deployed compass version...
ERROR: version mismatch for compass.
  Deployed: 2.0.0-alpha.2
  Runtime:  2.0.0-alpha.3

Rerun ./deploy.py to update the environment and load scripts. If you know or suspect that the dependencies have changed, rerun ./deploy.py even if the version has not.

If you use a directory for each branch, the simplest approach is to run ./deploy.py in each worktree. By default, each worktree gets its own pixi-env directory and load scripts, so the worktrees are independent of one another.

You can instead share one pixi environment between worktrees with ./deploy.py --pixi-path <path> as long as the branches have the same dependencies. In that case, the compass package in the shared environment points to whichever worktree you ran ./deploy.py from most recently, and sourcing a load script from another worktree does not change that. To switch worktrees, either rerun ./deploy.py --pixi-path <path> from the worktree you want to use or, with the environment activated, run:

python -m pip install --no-deps --no-build-isolation -e .

from the root of that worktree. The pip command is much faster than ./deploy.py but skips the check that the dependencies are up to date.

Note

If you wish to switch between environments created for different compass branches or applications, the best practice is to end the current terminal session and start a new session with a clean environment before sourcing the other compass load script. Similarly, if you want to run a job script that itself sources the load script, it’s best to start a new terminal without having sourced a load script at all.

Troubleshooting

If you run into trouble with the environment or just want a clean start, you can run:

./deploy.py [--machine <machine>] [--compiler <compiler> ...] \
    [--mpi <mpi> ...] [--deploy-spack] [--no-spack] --recreate

The --recreate flag will delete the deployment artifacts and create them from scratch. This takes just a little extra time.

Creating/updating only the compass environment

For some workflows, you may only want to create the pixi environment and not build or reuse Spack environments. In such cases, run:

./deploy.py --no-spack

When --no-spack is not used, omitting --deploy-spack still means Compass will try to reuse any required pre-existing Spack environments.

To update only the bootstrap environment used internally by deployment, run:

./deploy.py --bootstrap-only

As above, source a generated load script each time you want to work with compass. The load script sets COMPASS_LOAD_SCRIPT, which compass uses to make the load_compass_env.sh symlink in each work directory.

Building MPAS components

The MPAS repository is a submodule of the compass repository. For example, to compile MPAS-Ocean:

source ./load_*.sh
cd E3SM-Project/components/mpas-ocean/
make <mpas_make_target>

MALI can be compiled with or without the Albany library that contains the first-order velocity solver. The Albany first-order velocity solver is the only velocity option that is scientifically validated, but the Albany library is not available for every compiler yet. Therefore, in some situations it is desirable to compile without Albany to run basic tests on platforms where Albany is not available. This basic mode of MALI can be compiled similarly to MPAS-Ocean, i.e.:

source ./load_*.sh
cd MALI-Dev/components/mpas-albany-landice
make <mpas_make_target>

Compiling MALI with Albany has not yet been standardized. Some information is available at https://github.com/MALI-Dev/E3SM/wiki, and complete instructions will be added here in the future.

See the last column of the table in Supported Machines for the right <mpas_make_target> command for each machine and compiler.

Running compass from the repo

If you follow the procedure above, you can run compass with the compass command-line tool exactly like described in the User’s Guide Quick Start for Users and as detailed in Command-line interface.

To list test cases you need to run:

compass list

The results will be the same as described in Setting up test cases, but the test cases will come from the local compass directory.

To set up a test case, you will run something like:

compass setup -t ocean/global_ocean/QU240/mesh -m $MACHINE -w $WORKDIR -p $MPAS

where $MACHINE is an ES3M machine, $WORKDIR is the location where compass test cases will be set up and $MPAS is the directory where the MPAS model executable has been compiled. See compass setup for details.

To list available test suites, you would run:

compass list --suites

And you would set up a suite as follows:

compass suite -s -c ocean -t nightly -m $MACHINE -w $WORKDIR -p $MPAS

When you want to run the code, go to the work directory (for the suite or test case), log onto a compute node (if on an HPC machine) and run:

source load_compass_env.sh
compass run

The first command will source the same activation script that you used to set up the suite or test case (load_compass_env.sh is just a symlink to the load script you sourced before setting up the suite or test case).

Code style for compass

compass complies with the coding conventions of PEP8. Rather than memorize all the guidelines, the easiest way to stay in compliance as a developer writing new code or modifying existing code is to use a PEP8 style checker. One option is to use an IDE with a PEP8 style checker built in, such as PyCharm. See this tutorial for some tips on checking code style in PyCharm.

Here’s the manual way to check for PEP8 compliance.

Flake8 is a PEP8 checker that is included in the compass development environment. For each of the files you have modified, you can run the Flake8 checker to see a list of all instances of non-compliance in that file.

$flake8 example.py
example.py:77:1: E302 expected 2 blank lines, found 1

For this example, we would just add an additional blank line after line 77 and run the checker again to make sure we’ve resolved the issue.

Once you open a pull request for your feature, there is an additional PEP8 style checker at this stage.

Set up a compass repository with worktrees: for advanced users

This section uses git worktree, which provides more flexibility but is more complicated. See the beginner section above for the simpler version. In the worktree version, you will have many unix directories, and each corresponds to a git branch. It is easier to keep track of, and easier to work with many branches at once. Begin where you keep your repositories:

mkdir compass
cd compass
git clone git@github.com:MPAS-Dev/compass.git main
cd main

The MPAS-Dev/compass repo is now origin. You can add more remotes. For example:

git remote add mark-petersen git@github.com:mark-petersen/compass.git
git fetch mark-petersen

To view all your remotes:

git remote -v

To view all available branches, both local and remote:

git branch -a

We will use the git worktree command to create a new local branch in its own unix directory:

cd compass/main
git worktree add -b new_branch_name ../new_branch_name origin/main
cd ../new_branch_name

In this example, we branched off origin/main, but you could start from any branch, which is specified by the last git worktree argument.

There are two ways to build the MPAS executable:

Compass submodule (easier): This guarantees that the MPAS commit matches compass. It is also the default location for finding the MPAS model so you don’t need to specify the -p flag at the command line or put the MPAS model path in your config file (if you even need a config file at all):
```
git submodule update --init --recursive
cd E3SM-Project/components/mpas-ocean/
# load modules
make gfortran
```
For the “load modules” step, see Machines for specific instructions.
Other E3SM directory (advanced): Create your own clone of the E3SM-Project/E3SM or MALI-Dev/E3SM repository elsewhere on disk. Either make an ocean.cfg or landice.cfg that specifies the absolute path to the path where the ocean_model or landice_model executable is found, or specify this path on the command line with -p. You are responsible for knowing if this particular version of MPAS component’s code is compatible with the version of compass that you are using. The simplest way to set up a new repo for MALI development in a new directory is:
```
git clone git@github.com:MALI-Dev/E3SM.git your_new_branch
cd your_new_branch
git checkout -b your_new_branch origin/develop
```
The equivalent for MPAS-Ocean development would be:
```
git clone git@github.com:E3SM-Project/E3SM.git your_new_branch
cd your_new_branch
git checkout -b your_new_branch origin/main
```