Bun Runtime Guide

tywrap works with Bun 1.1+ using the same NodeBridge as Node.js. No separate bridge is needed.

Installation

bun add tywrap
pip install tywrap-ir

Basic Setup

import { NodeBridge } from 'tywrap/node';
import { setRuntimeBridge } from 'tywrap/runtime';

setRuntimeBridge(new NodeBridge({
  pythonPath: 'python3',
  virtualEnv: '.venv',
  timeoutMs: 30000,
}));

Both 'tywrap/node' and 'tywrap' work on Bun. Use 'tywrap/node' for smaller bundles through tree-shaking.

Configuration Options

NodeBridge accepts the same options under Bun as under Node.js. See the Node.js guide for the full option reference.

Key options:

Option	Default	Description
pythonPath	auto-detect	Path to python3 executable
virtualEnv	not set	Path to virtual environment directory
timeoutMs	30000	Request timeout in milliseconds
inheritProcessEnv	false	Set true to pass full process.env to subprocess

bunfig.toml

The repository's bunfig.toml contains these build and run settings:

[build]
target = "bun"
format = "esm"
splitting = true
sourcemap = "external"
external = ["pyodide"]

[dev]
hot = true

Running Bun-Specific Tests

npm run test:bun

Or directly:

LC_ALL=C LANG=C bun run vitest --run test/runtime_bun.test.ts

Virtual Environments

setRuntimeBridge(new NodeBridge({
  pythonPath: '.venv/bin/python',
  virtualEnv: '.venv',
}));

Environment Variables

The same TYWRAP_* env vars work under Bun. See the environment variables reference.

Troubleshooting

python3: command not found: set pythonPath explicitly or ensure Python is on PATH.

For a subprocess timeout, increase timeoutMs. Verify pip install tywrap-ir ran in the correct environment.

The Node.js troubleshooting guide has more patterns that also apply to Bun.