Advanced: (Beta) Building and Installing Pre-Compiled Basilisk Wheels

Warning

This method of building Basilisk is currently a beta feature, and should only be attempted by advanced users familiar with Python packaging and distribution. This method is not yet guaranteed to work on every platform, and there are still some annoyances to iron out, but we appreciate any feedback you may have.

Most users should see Building the Software Framework for documentation on the regular build process.

Building and Installing with pip

Note

All commands are called from the Basilisk root directory.

A clean Basilisk wheel can be built and installed using standard Python packaging tools [1] such as pip. Note that this will always result in a clean build. The simplest usage is:

pip install -v .

This command compiles and installs Basilisk into the user’s current Python environment. Note that the optional -v flag is added to display verbose compilation messages, otherwise it can look like the installation process is stuck.

Build options (as passed to conanfile.py and described in Building the Software Framework) can be provided using the CONAN_ARGS environment variable:

CONAN_ARGS="--pathToExternalModules='/path/to/external' --opNav True" pip install -v .

Warning

For backwards compatibility reasons, and due to issues arising from temporary build environments, editable installations (pip install -e .) are not currently supported. Please follow the standard Building the Software Framework process.

On its own, there is no significant benefit to installing Basilisk in this way. However, supporting standard Python packaging tools means that Basilisk can now be built into a pre-compiled “wheel” (.whl) file that can be shared and installed on other compatible machines.

Using pip, the command below will generate a Basilisk-*.whl file in the current directory:

pip wheel --no-deps -v .

The resulting wheel file can then be installed using pip:

pip install Basilisk-*.whl

The main benefit of this approach will come in the future, when a set of pre-compiled wheels will be made available, allowing most users to easily pip install Basilisk without compilation, in the same way that packages like numpy, scipy, and pandas are available.

Wheel Compatibility

Warning

Wheel compatibility is currently being verified across Python versions and different platforms. So far, some users have reported successfully installing the same wheel on different Ubuntu versions and with different Python versions, but your mileage may vary.

If you choose to try this feature and run into and problems, please raise an issue for the Basilisk maintainers to investigate.

When installed using a standard Python packaging tool such as pip, Basilisk will automatically be built using the Python Limited C API. The resulting wheel file will contain a set of compiled Python extension modules that, at least in theory, can be run using any compatible Python version (currently, any from Python 3.8 to 3.11).

To maintain backwards compatibility, standard Basilisk installations via python conanfile.py are not compatible between different Python versions, as is stated in Using a Custom Python Installation. However, users can also forcibly build with the Python Limited C API by providing the --pyLimitedAPI flag:

python conanfile.py --pyLimitedAPI 0x030800f0

For Maintainers: Overview of Implementation

Python packaging support is provided through the pyproject.toml file as specified by the PEP-517 standard. This file defines the desired “back-end” tool used to build Basilisk, as well as other packaging settings including which Python packages are required for building and running Basilisk.

At the time of this writing, the build backend is setuptools, which invokes the setup.py file to perform the build. In setup.py, the Python extension builder is overridden with a custom builder that computes an appropriate Python Limited C API version (based on the minimum supported Python version specified in pyproject.toml). The builder then invokes python conanfile.py, setting the --managePipEnvironment False option so that Conan does not directly manipulate the user’s pip environment. The main reasons for this setting was to maintain the current default behaviour of conanfile.py-based installation.

Editable installations (i.e. pip install -e .) are not currently supported for two main reasons:

  1. pip install -e . is currently overridden to maintain the existing python conanfile.py behaviour.

  2. Due to the underlying CMake build system, editable installs with pip require setting the --no-build-isolation option, which means that the user must manually install the build requirements. Since these build requirements are installed automatically by the standard conanfile.py installation, it is the recommended method for editable installations.

Tools such as cibuildwheel can be used to build wheels that are automatically compatible with a broad range of operating system versions. These pre-compiled wheels can then be shared publicly using tools like twine to upload them to the Python Package Index (PyPi), allowing users to simply pip install Basilisk. We expect that these tools will be added into the Basilisk Continuous Integration pipeline in the future.

Further discussions and implementation details can be found in Basilisk merge request #737.

Footnotes