componentize-py 0.3.2

Tool to package Python applications as WebAssembly components

componentize-py

This is a tool to convert a Python application to a WebAssembly component. It takes the following as input:

• a WIT file or directory
• the name of a WIT world defined in the above file or directory
• the name of a Python module which targets said world
• a list of directories in which to find the Python module and its dependencies

The output is a component which may be run using e.g. wasmtime. See the tests for examples.

For an example of running a sandboxed Python guest within a Python host, see component-sandbox-demo.

Installing from PyPI

pip install componentize-py

Building from source

For the time being, we use a temporary fork of WASI-SDK which enables both shared library support and dlopen/dlsym. Once those features are upstreamed, we'll switch. Specifically, the remaining patches are:

• https://github.com/WebAssembly/wasi-libc/pull/429
• https://github.com/WebAssembly/wasi-sdk/pull/338
• Additional, yet-to-be created PRs to enable dlopen/dlsym

Prerequisites

• Tools needed to build CPython (Make, Clang, etc.)
• Rust stable 1.68 or later and nightly 2023-07-27 or later, including the wasm32-wasi and wasm32-unknown-unknown targets
  • Note that we currently use the -Z build-std Cargo option to build the componentize-py runtime with position-independent code (which is not the default for wasm32-wasi) and this requires using a recent nightly build of Rust.

For Rust, something like this should work once you have rustup:

rustup update
rustup install nightly
rustup component add rust-src --toolchain nightly
rustup target add wasm32-wasi wasm32-unknown-unknown

Building and Running

First, make sure you've got all the submodules cloned.

git submodule update --init --recursive

Next, install WASI SDK to /opt/wasi-sdk (alternatively, you can specify an alternative location and reference it later using the WASI_SDK_PATH environment variable). Replace linux with macos or mingw (Windows) below depending on your OS.

curl -LO https://github.com/dicej/wasi-sdk/releases/download/shared-library-alpha-2/wasi-sdk-20.16g86c5c116b0a6-linux.tar.gz
tar xf wasi-sdk-20.16g86c5c116b0a6-linux.tar.gz
sudo mv wasi-sdk-20.16g86c5c116b0a6 /opt/wasi-sdk
export WASI_SDK_PATH=/opt/wasi-sdk

Finally, build and run componentize-py.

cargo run --release -- --help