bun-plugin-pino

Why?

Pino uses worker threads internally. Some dependencies and any transports need to be bundled separately or they won't get resolved at runtime and you'll get errors like error: unable to determine transport target for "...".

Do your bundles work on the machine that built them, but break in other environments like Docker? It's because Bun will resolve and and hardcode absolute paths from this particular environment into the bundle. Runtime resolution of these modules will fail elsewhere.

How?

This plugin bundles Pino's dependencies separately and fixes runtime imports in the main bundle. It supports Node and Bun targets with ESM format only.

Install

bun add -d bun-plugin-pino

Use the JS API to build

import { bunPluginPino } from 'bun-plugin-pino';

await Bun.build({
  entrypoints: ['./src/index.ts'],
  outdir: './dist',
  plugins: [
    bunPluginPino({
      transports: ['pino-loki'], // any additional transports you may be using
      // logging?: "default" | "plain" | "quiet"
    }),
  ],
});

Output

./dist
├── index.js
├── thread-stream-worker.js
├── pino-file.js
└── pino-worker.js
└── [transport].js

Notes

If you have several libraries that don't play well with the bundler it's probably easier to:

1. mark them as external
2. resolve them in your build script using import.meta.resolve('foo')
3. add them as dependencies with strict versions to a new package.json to be used at runtime
4. bun install --production to get a slim runtime node_modules in a docker image or what have you

This is the workaround I'm using with a monorepo because Bun doesn't support scoped installs at the time of writing.

Thanks

This code is based off of esbuild-plugin-pino by David Peng