Developer’s Guide

The below sections will walk through how to set up a development environment, make changes to the code, and test that they work. See the How to contribute section for more information on getting started and contributor expectations. Additional information for developer’s can be found at the pages listed below.

Coding guidelines

Satpy is part of Pytroll, and all code should follow the Pytroll coding guidelines and best practices.

Satpy is now Python 3 only and it is no longer needed to support Python 2. Check pyproject.toml for the current Python versions any new code needs to support.

Development installation

See the Installation Instructions section for basic installation instructions. When it comes time to install Satpy it should be installed from a clone of the git repository and in development mode so that local file changes are automatically reflected in the python environment. We highly recommend making a separate conda environment or virtualenv for development. For example, you can do this using conda:

conda create -n satpy-dev python=3.11
conda activate satpy-dev

This will create a new environment called “satpy-dev” with Python 3.11 installed. The second command will activate the environment so any future conda, python, or pip commands will use this new environment.

If you plan on contributing back to the project you should first fork the repository and clone your fork. The package can then be installed in development mode by doing:

conda install --only-deps satpy
pip install -e .

The first command will install all dependencies needed by the Satpy conda-forge package, but won’t actually install Satpy. The second command should be run from the root of the cloned Satpy repository (where the pyproject.toml is) and will install the actual package.

You can now edit the python files in your cloned repository and have them immediately reflected in your conda environment.

All the required dependencies for a full development environment, i.e. running the tests and building the documentation, can be installed with:

conda install eccodes
pip install -e ".[all]"

Running tests

Satpy tests are written using the third-party pytest package. There is usually no need to run all Satpy tests, but instead only run the tests related to the component you are working on. All tests are automatically run from the GitHub Pull Request using multiple versions of Python, multiple operating systems, and multiple versions of dependency libraries. If you want to run all Satpy tests you will need to install additional dependencies that aren’t needed for regular Satpy usage. To install them run:

conda install eccodes
pip install -e ".[tests]"

Satpy tests can be executed by running:

pytest satpy/tests

You can also run a specific tests by specifying a sub-directory or module:

pytest satpy/tests/reader_tests/

Running benchmarks

Satpy benchmarks are written using the Airspeed Velocity package (asv). The benchmarks can be run using:

asv run

These are pretty computation intensive, and shouldn’t be run unless you want to diagnose some performance issue for example.

Once the benchmarks have run, you can use:

asv publish
asv preview

to have a look at the results. Again, have a look at the asv documentation for more information.


Satpy’s documentation is built using Sphinx. All documentation lives in the doc/ directory of the project repository. For building the documentation, additional packages are needed. These can be installed with

pip install -e ".[all]"

After editing the source files there the documentation can be generated locally:

cd doc
make html

The output of the make command should be checked for warnings and errors. If code has been changed (new functions or classes) then the API documentation files should be regenerated before running the above command:

sphinx-apidoc -f -T -o source/api ../satpy ../satpy/tests