Trimming Unused Resources

By default, packaging rules are very aggressive about pulling in resources such as Python modules. For example, the entire Python standard library is embedded into the binary by default. These extra resources take up space and can make your binary significantly larger than it could be.

It is often desirable to prune your application of unused resources. For example, you may wish to only include Python modules that your application uses. This is possible with PyOxidizer.

Essentially, all strategies for managing the set of packaged resources boil down to crafting config file logic that chooses which resources are packaged.

But maintaining explicit lists of resources can be tedious. PyOxidizer offers a more automated approach to solving this problem.

The PythonInterpreterConfig type defines a write_modules_directory_env setting, which when enabled will instruct the embedded Python interpreter to write the list of all loaded modules into a randomly named file in the directory identified by the environment variable defined by this setting. For example, if you set write_modules_directory_env="PYOXIDIZER_MODULES_DIR" and then run your binary with PYOXIDIZER_MODULES_DIR=~/tmp/dump-modules, each invocation will write a ~/tmp/dump-modules/modules-* file containing the list of Python modules loaded by the Python interpreter.

One can therefore use write_modules_directory_env to produce files that can be referenced in a different build target to filter resources through a set of only include names.

TODO this functionality was temporarily dropped as part of the Starlark port.