Config Files

compass uses config files (with extension .cfg) to allow users to control how Test Cases and Test Suites get set up and run.

A “user” config file

If you’re running on one of the supported Machines, and you provide a path to where you build the MPAS model (with the -p flag to compass setup and compass suite, see Setting up test cases and Test Suites), you also won’t need to create a config file to set up test cases or suites.

If you’re running on another machine like your own laptop, you will need to provide some basic information for compass to work properly. Even if you’re running on one of the supported machines, you might find it convenient to make your own changes to config options related to either setting up or running test suites and test case.

Here is an example:


mpas_model = .

# The root to a location where the mesh_database, initial_condition_database,
# and bathymetry_database for MPAS-Ocean will be cached
ocean_database_root = /home/xylar/data/mpas/mpas_standalonedata/mpas-ocean

# The root to a location where the mesh_database and initial_condition_database
# for MALI will be cached
landice_database_root = /home/xylar/data/mpas/mpas_standalonedata/mpas-albany-landice

# The parallel section describes options related to running tests in parallel

# parallel system of execution: slurm or single_node
system = single_node

# whether to use mpirun or srun to run the model
parallel_executable = mpirun

# cores per node on the machine
cores_per_node = 8

# the number of multiprocessing or dask threads to use
threads = 8

The comments in this example are hopefully pretty self-explanatory. In this example, the mpas_model path points to the current directory .. You can replace this with the relative or absolute path where you have built the model (i.e. where the ocean_model or landice_model executables are found). Since you are free to run compass from wherever you like, the example assumes you are running from the directory where the MPAS model was built. You may prefer to keep your compass config files in another location, in which case you could provide an absolute path like:

# The paths section points compass to external paths

# the relative or absolute path to the root of a branch where MPAS-Ocean
# has been built
mpas_model = /home/xylar/code/E3SM/components/mpas-ocean

You provide the config file to compass setup and compass suite with the -f flag:

compass setup -f my_machine.cfg ...

Test-case config files

Once a test case has been set up, its work directory will contain a config file called <test_case>.cfg, where <test_case> is the name of the test case. As a user, you can typically leave the config options in a test case as they are to run the test in its default configuration. But the config file is meant to make it easier to modify the test case to fit your needs without having to dig into the compass code.

Config options for a given test case are built up from a number of different sources:

  • the default config file, default.cfg, which sets a few options related to downloading files during setup (whether to download and whether to check the size of files already downloaded)

  • the machine config file (using machines/default.cfg if no machine was specified) with information on the parallel system and the paths to cached data files

  • the MPAS core’s config file. For the Ocean core core, this sets default paths to the MPAS-Ocean model build (including the namelist templates). It uses extended interpolation in the config file to use config options within other config options, e.g. model = ${paths:mpas_model}/ocean_model.

  • the test group’s config file if one is defined. For idealized test groups, these often include the size and resolution of the mesh as well as the number of vertical levels. They may include options that were flags to scripts or init-mode namelist options in Legacy COMPASS.

  • any number of config files from the test case. There might be different config options depending on how the test case is configured (e.g. only if a certain feature is enabled. For example, global_ocean loads different sets of config options for different meshes.

  • a user’s config file described above.

You are free to add any sections and config options to your config file, in which case they will override the values specified in one of the other config files listed above. Here is an example of some customization for the global_ocean test group:

# options for global ocean testcases

# The following options are detected from .gitconfig if not explicitly entered
author = Xylar Asay-Davis
email =
pull_request =

In this example, the author’s name and email address, and the path to a pull request will be included in the metadata for output files from this test group.

A typical config file resulting from combining all of the sources listed above looks like:

server_base_url =
download = True
check_size = False
verify = True
core_path = mpas-ocean

partition_executable = gpmetis
system = single_node
parallel_executable = mpirun
cores_per_node = 8
threads = 8

mpas_model = /home/xylar/code/mpas-work/compass/compass_1.0/E3SM-Project/components/mpas-ocean
ocean_database_root = /home/xylar/data/mpas/mpas_standalonedata/mpas-ocean
landice_database_root = /home/xylar/data/mpas/mpas_standalonedata/mpas-albany-landice
baseline_dir = /home/xylar/data/mpas/test_20210413/compass_classes/ocean/global_ocean/QU240/PHC/init

forward = /home/xylar/code/mpas-work/compass/compass_1.0/E3SM-Project/components/mpas-ocean/default_inputs/namelist.ocean.forward
init = /home/xylar/code/mpas-work/compass/compass_1.0/E3SM-Project/components/mpas-ocean/default_inputs/namelist.ocean.init

forward = /home/xylar/code/mpas-work/compass/compass_1.0/E3SM-Project/components/mpas-ocean/default_inputs/streams.ocean.forward
init = /home/xylar/code/mpas-work/compass/compass_1.0/E3SM-Project/components/mpas-ocean/default_inputs/streams.ocean.init

model = /home/xylar/code/mpas-work/compass/compass_1.0/E3SM-Project/components/mpas-ocean/ocean_model

iterations = 10

mesh_cores = 1
mesh_min_cores = 1
mesh_max_memory = 1000
mesh_max_disk = 1000
init_cores = 4
init_min_cores = 1
init_max_memory = 1000
init_max_disk = 1000
init_threads = 1
forward_cores = 4
forward_min_cores = 1
forward_threads = 1
forward_max_memory = 1000
forward_max_disk = 1000
add_metadata = True
prefix = QU
mesh_description = MPAS quasi-uniform mesh for E3SM version ${e3sm_version} at
    ${min_res}-km global resolution with ${levels} vertical
bathy_description = Bathymetry is from GEBCO 2019, combined with BedMachine Antarctica around Antarctica.
init_description = Polar science center Hydrographic Climatology (PHC)
e3sm_version = 2
mesh_revision = 1
min_res = 240
max_res = 240
max_depth = autodetect
levels = autodetect
creation_date = autodetect
author = Xylar Asay-Davis
email =
pull_request =

enable_ocean_initial_condition = true
enable_ocean_graph_partition = true
enable_seaice_initial_condition = true
enable_scrip = true
enable_diagnostics_files = true
comparisonlatresolution = 0.5
comparisonlonresolution = 0.5
comparisonantarcticstereowidth = 6000.
comparisonantarcticstereoresolution = 10.
comparisonarcticstereowidth = 6000.
comparisonarcticstereoresolution = 10.

grid_type = tanh_dz
vert_levels = 16
bottom_depth = 3000.0
min_layer_thickness = 3.0
max_layer_thickness = 500.0

Unfortunately, all comments are lost in the process of combining config options. Comments are not parsed by ConfigParser, and there is not a standard for which comments are associated with which options. So users will need to search through this documentation (or the code on the compass repo) to know what the config options are used for.