# pino-abstract-transport

> Write Pino transports easily

Latest version **3.0.0** (published 2025-10-06) · MIT license · 0 weekly downloads

## Install

```sh
npm install pino-abstract-transport
pnpm add pino-abstract-transport
yarn add pino-abstract-transport
bun add pino-abstract-transport
```

## Health

**Score 55/100 (C)** — status: stable.

Positive: has types; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

## Facts

| | |
|---|---|
| Version | 3.0.0 |
| Published | 2025-10-06 |
| First published | 2021-04-10 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | CommonJS |
| Dependencies | 1 |
| Unpacked size | 38.8 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 45 |
| Author | Matteo Collina |
| Maintainers | matteo.collina, jsumners, watson |
| Keywords | pino, transport |

## Links

- npm: https://www.npmjs.com/package/pino-abstract-transport
- Repository: https://github.com/pinojs/pino-abstract-transport
- Homepage: https://github.com/pinojs/pino-abstract-transport#readme
- Issues: https://github.com/pinojs/pino-abstract-transport/issues
- npm.io page: https://npm.io/package/pino-abstract-transport

## Dependencies (1)

- [split2](https://npm.io/package/split2.md) ^4.0.0

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## Recent versions

- 3.0.0 (latest) — 2025-10-06
- 2.0.0 — 2024-09-03
- 1.2.0 — 2024-04-22
- 1.1.0 — 2023-09-04
- 1.0.0 — 2022-06-20
- 0.5.0 — 2021-11-03
- 0.4.0 — 2021-10-02
- 0.3.0 — 2021-09-16
- 0.2.0 — 2021-05-19
- 0.1.0 — 2021-04-10

## README

# pino-abstract-transport
[![npm version](https://img.shields.io/npm/v/pino-abstract-transport)](https://www.npmjs.com/package/pino-abstract-transport)
[![Build Status](https://img.shields.io/github/actions/workflow/status/pinojs/pino-abstract-transport/ci.yml?branch=main)](https://github.com/pinojs/pino-abstract-transport/actions)
[![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat)](https://standardjs.com/)

Write Pino transports easily.

## Install

```sh
npm i pino-abstract-transport
```

## Usage

```js
import build from 'pino-abstract-transport'

export default async function (opts) {
  return build(async function (source) {
    for await (let obj of source) {
      console.log(obj)
    }
  })
}
```

or in CommonJS and streams:

```js
'use strict'

const build = require('pino-abstract-transport')

module.exports = function (opts) {
  return build(function (source) {
    source.on('data', function (obj) {
      console.log(obj)
    })
  })
}
```

## Typescript usage

Install the type definitions for node. Make sure the major version of the type definitions matches the node version you are using.

#### Node 16

```sh
npm i -D @types/node@16
```

## API

### build(fn, opts) => Stream

Create a [`split2`](http://npm.im/split2) instance and returns it.
This same instance is also passed to the given function, which is called
synchronously.

If `opts.transform` is `true`, `pino-abstract-transform` will 
wrap the split2 instance and the returned stream using [`duplexify`](https://www.npmjs.com/package/duplexify),
so they can be concatenated into multiple transports.

#### Events emitted

In addition to all events emitted by a [`Readable`](https://nodejs.org/api/stream.html#stream_class_stream_readable)
stream, it emits the following events:

* `unknown` where an unparsable line is found, both the line and optional error is emitted.

#### Options

* `parse` an option to change to data format passed to build function. When this option is set to `lines`,
  the data is passed as a string, otherwise the data is passed as an object. Default: `undefined`.

* `close(err, cb)` a function that is called to shutdown the transport. It's called both on error and non-error shutdowns.
  It can also return a promise. In this case discard the the `cb` argument.

* `parseLine(line)` a function that is used to parse line received from `pino`.

* `expectPinoConfig` a boolean that indicates if the transport expects Pino to add some of its configuration to the stream. Default: `false`.

## Example

### custom parseLine

You can allow custom `parseLine` from users while providing a simple and safe default parseLine.

```js
'use strict'

const build = require('pino-abstract-transport')

function defaultParseLine (line) {
  const obj = JSON.parse(line)
  // property foo will be added on each line
  obj.foo = 'bar'
  return obj
}

module.exports = function (opts) {
  const parseLine = typeof opts.parseLine === 'function' ? opts.parseLine : defaultParseLine
  return build(function (source) {
    source.on('data', function (obj) {
      console.log(obj)
    })
  }, {
    parseLine: parseLine
  })
}
```

### Stream concatenation / pipeline

You can pipeline multiple transports:

```js
const build = require('pino-abstract-transport')
const { Transform, pipeline } = require('stream')

function buildTransform () {
  return build(function (source) {
    return new Transform({
      objectMode: true,
      autoDestroy: true,
      transform (line, enc, cb) {
        line.service = 'bob'
        cb(null, JSON.stringify(line))
      }
    })
  }, { enablePipelining: true })
}

function buildDestination () {
  return build(function (source) {
    source.on('data', function (obj) {
      console.log(obj)
    })
  })
}

pipeline(process.stdin, buildTransform(), buildDestination(), function (err) {
  console.log('pipeline completed!', err)
})
```

### Using pino config

Setting `expectPinoConfig` to `true` will make the transport wait for pino to send its configuration before starting to process logs. It will add `levels`, `messageKey` and `errorKey` to the stream.

When used with an incompatible version of pino, the stream will immediately error.

```js
import build from 'pino-abstract-transport'

export default function (opts) {
  return build(async function (source) {
    for await (const obj of source) {
      console.log(`[${source.levels.labels[obj.level]}]: ${obj[source.messageKey]}`)
    }
  }, {
    expectPinoConfig: true
  })
}
```

## License

MIT

---
_Source: https://npm.io/package/pino-abstract-transport · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._