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Version: 2.21

PyOxidizer

Creating Python binaries through PyOxidizer.

PyOxidizer allows you to distribute your code as a single binary file, similar to Pex files. Unlike Pex, these binaries include a Python interpreter, often greatly simplifying distribution.

See our blog post on Packaging Python with the Pants PyOxidizer Plugin for more discussion of the benefits of PyOxidizer.

Step 1: Activate the backend​

Add this to your pants.toml:

pants.toml
[GLOBAL]
backend_packages.add = [
  "pants.backend.experimental.python.packaging.pyoxidizer",
  "pants.backend.python",
]

This adds the new pyoxidizer_binary target, which you can confirm by running pants help pyoxidizer_binary.

This backend is experimental

We are still discovering the best ways to provide PyOxidizer support, such as how to make our default template more useful. This backend does not follow the normal deprecation policy, although we will do our best to minimize breaking changes.

We would love your feedback on this backend!

Step 2: Define a python_distribution target​

The pyoxidizer_binary target works by pointing to a python_distribution target with the code you want included. Pants then passes the distribution to PyOxidizer to install it as a binary.

So, to get started, create a python_distribution target per Building distributions.

project/BUILD
python_sources(name="lib")

python_distribution(
    name="dist",
    dependencies=[":lib"],
    provides=python_artifact(name="my-dist", version="0.0.1"),
)

The python_distribution must produce at least one wheel (.whl) file. If you are using Pants's default of generate_setup=True, make sure you also use Pants's default of wheel=True. Pants will eagerly error when building your pyoxidizer_binary if you use a python_distribution that does not produce wheels.

Step 3: Define a pyoxidizer_binary target​

Now, create a pyoxidizer_binary target and set the dependencies field to the address of the python_distribution you created previously.

project/BUILD
pyoxidizer_binary(
    name="bin",
    dependencies=[":dist"],
)

Usually, you will want to set the entry_point field, which sets the behavior for what happens when you run the binary.

If the entry_point field is not specified, running the binary will launch a Python interpreter with all the relevant code and dependencies loaded.

❯ ./dist/bin/x86_64-apple-darwin/release/install/bin
Python 3.9.7 (default, Oct 18 2021, 00:59:13)
[Clang 13.0.0 ] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from myproject import myapp
>>> myapp.main()
Hello, world!
>>>

You can instead set entry_point to the Python module to execute (e.g. myproject.myapp). If specified, running the binary will launch the application similar to if it had been run as python -m myproject.myapp, for example.

pyoxidizer_binary(
    name="bin",
    dependencies=[":dist"],
    entry_point="myproject.myapp",
)
❯ ./dist/bin/x86_64-apple-darwin/release/install/bin
Launching myproject.myapp from __main__
Hello, world!

Step 4: Run package or run goals​

Finally, run pants package $address on your pyoxidizer_binary target to create a directory including your binary, or pants run $address to launch the binary.

For example:

❯ pants package src/py/project:bin
14:15:31.18 [INFO] Completed: Building src.py.project:bin with PyOxidizer
14:15:31.23 [INFO] Wrote dist/src.py.project/bin/aarch64-apple-darwin/debug/install/bin
❯ pants run src/py/project:bin
14:15:31.18 [INFO] Completed: Building src.py.project:bin with PyOxidizer
Hello, world!

By default, with the package goal, Pants will write the package using this scheme: dist/{path.to.tgt_dir}/{tgt_name}/{platform}/{debug,release}/install/{tgt_name}. You can change the first part of this path by setting the output_path field, although you risk name collisions with other pyoxidizer_binary targets in your project. See pyoxidizer_binary for more info.

debug vs release builds

By default, PyOxidizer will build with Rust's "debug" mode, which results in much faster compile times but means that your binary will be slower to run. Instead, you can instruct PyOxidizer to build in release mode by adding this to pants.toml:

[pyoxidizer]
args = ["--release"]

Or by using the command line flag pants --pyoxidizer-args='--release' package path/to:tgt.

Advanced use cases​

Missing functionality? Let us know!

We would like to keep improving Pants's PyOxidizer support. We encourage you to let us know what features are missing through Slack or GitHub!

[python-repos] not yet supported for custom indexes

Currently, PyOxidizer can only resolve dependencies from PyPI and your first-party code. If you need support for custom indexes, please let us know by commenting on https://github.com/pantsbuild/pants/issues/14619.

(We'd be happy to help mentor someone through this change, although please still comment either way!)

python_distributions that implicitly depend on each other​

As explained at Building distributions, Pants automatically detects when one python_distribution depends on another, and it will add that dependency to the install_requires for the distribution.

When this happens, PyOxidizer would naively try installing that first-party dependency from PyPI, which will likely fail. Instead, include all relevant python_distribution targets in the dependencies field of the pyoxidizer_binary target.

python_sources(name="lib")

python_distribution(
    name="dist",
    # Note that this python_distribution does not
    # explicitly include project/utils:dist in its
    # `dependencies` field, but Pants still
    # detects an implicit dependency and will add
    # it to this dist's `install_requires`.
    dependencies=[":lib"],
    provides=setup_py(name="main-dist", version="0.0.1"),
)

pyoxidizer_binary(
    name="bin",
    entry_point="hellotest.main",
    dependencies=[":dist", "project/utils:dist"],
)

template field​

If the default PyOxidizer configuration that Pants generates is too limiting, a custom template can be used instead. Pants will expect a file with the extension .bzlt in a path relative to the BUILD file.

pyoxidizer_binary(
    name="bin",
    dependencies=[":dist"],
    entry_point="myproject.myapp",
    template="pyoxidizer.bzlt",
)

The custom .bzlt may use four parameters from within the Pants build process inside the template (these parameters must be prefixed by $ or surrounded with ${ } in the template).

  • RUN_MODULE - The re-formatted entry_point passed to this target (or None).
  • NAME - This target's name.
  • WHEELS - All python distributions passed to this target (or []).
  • UNCLASSIFIED_RESOURCE_INSTALLATION - This will populate a snippet of code to correctly inject the target's filesystem_resources.

For example, in a custom PyOxidizer configuration template, to use the pyoxidizer_binary target's name field:

exe = dist.to_python_executable(
    name="$NAME",
    packaging_policy=policy,
    config=python_config,
)

You almost certainly will want to include this line, which is how the dependencies field gets consumed:

exe.add_python_resources(exe.pip_install($WHEELS))

filesystem_resources field​

As explained in PyOxidizer's documentation, you may sometimes need to force certain dependencies to be installed to the filesystem. You can do that with the filesystem_resources field:

pyoxidizer_binary(
    name="bin",
    dependencies=[":dist"],
    entry_point="myproject.myapp",
    filesystem_resources=["numpy==1.17"],
)