7.3.0 • Public • Published


npm version Build Status js-standard-style

Lead maintainer: jsumners

This module provides a "transport" for pino that simply forwards messages to an arbitrary socket. The socket can be UDPv4 or TCPv4. The module can echo the received logs or work silently.

You should install pino-socket globally for ease of use:

$ npm install --production -g pino-socket

Usage as Pino Transport

You can use this module as a pino transport like so:

const pino = require('pino')
const transport = pino.transport({
  target: 'pino-socket',
  options: {
    address: '',
    port: 5000,
    mode: 'tcp'


Name Description
address The host address to connect to. Default:
port The host port to connect to. Default: 514.
unixsocket The unix socket path for the destination. Default: ​.
mode Either tcp or udp. Default: udp.
secure Enable secure (TLS) connection. Default: false.
noverify Allow connection to server with self-signed certificates. Default: false.
reconnect Enable reconnecting to dropped TCP destinations. Default: false.
reconnectTries Number of times to attempt reconnection before giving up. Default: Infinity.
backoffStrategy The backoff strategy to use on TCP destinations. The backoff strategy must implement the BackoffStrategy interface. lternatively, you can configure the backoff strategy using primitive data (see below). Default: new FibonacciStrategy(). The backoff strategy name, either exponential or fibonacci. Default: fibonacci.
backoffStrategy.randomisationFactor The backoff randomisation factor, must be between 0 and 1. Default: 0.
backoffStrategy.initialDelay The backoff initial delay in milliseconds. Default: 100.
backoffStrategy.maxDelay The backoff maximum delay in milliseconds. Default: 10000.
backoffStrategy.factor The exponential backoff factor, must be greater than 1. Default: 2.
recovery Enable a recovery mode when the TCP connection is lost which store data in a memory queue (FIFO) until the queue max size is reached or the TCP connection is restored. Default: false.
recoveryQueueMaxSize The maximum size of items added to the queue. When reached, oldest items "First In" will be evicted to stay below this size. Default: 1024.
recoveryQueueSizeCalculation Function used to calculate the size of stored items. The item is passed as the first argument and contains a data (Buffer) and encoding (String) attribute. Default: (item) => + item.encoding.length.
onBeforeDataWrite Function used to manipulate TCP data before being written to the socket. Operations preformed here must be synchronous. Format: (data) => Buffer. Default: null


Name Callback Signature Description
open (address: AddressInfo) => void Emitted when the TCP or UDP connection is established.
socketError (error: Error) => void Emitted when an error occurs on the TCP or UDP socket. The socket won't be closed.
socketClose (error: Error|null) => void Emitted after the TCP socket is closed. The argument error is defined if the socket was closed due to a transmission error.
close (hadError: Boolean) => void Emitted after the TCP or UDP socket is closed and won't reconnect. The argument hadError is a boolean which says if the socket was closed due to a transmission error.
reconnectFailure (error: Error|undefined) => void Emitted when the maximum number of backoffs (i.e., reconnect tries) is reached on a TCP connection.

IMPORTANT: In version prior to 6.0, an error event was emitted on the writable stream when an error occurs on the TCP or UDP socket. In other words, it was not possible to write data to the writable stream after an error occurs on the TCP or UDP socket. If you want to restore the previous behavior you can do:

transport.on('socketError', () => {

Alternatively, you can propagate the socket error using:

transport.on('socketError', (err) => {
  transport.emit('error', err)

In this case, make sure that you are listening to the error event otherwise you will get an Uncaught Error.

Usage as Pino Legacy Transport

Pino supports a legacy transport interface that is still supported by this module. Given an application foo that logs via pino, and a system that collects logs on port UDP 5000 on IP, you would use pino-socket like so:

$ node foo | pino-socket -a -p 5000


$ node foo | pino-socket -u /tmp/unix.sock

CLI Options

  • --settings (-s): read settings from a JSON file (switches take precedence).
  • --unixsocket (-u): the unix socket path for the destination. Default: ​.
  • --address (-a): the address for the destination socket. Default:
  • --port (-p): the port for the destination socket. Default: 514.
  • --mode (-m): either tcp or udp. Default: udp.
  • --secure (-tls): enable secure (TLS) connection for TCP (only works with --mode=tcp).
  • --noverify (-nv): allow connection to server with self-signed certificates (only works with --secure).
  • --reconnect (-r): enable reconnecting to dropped TCP destinations. Default: off.
  • --reconnectTries <n> (-t <n>): set number (<n>) of reconnect attempts before giving up. Default: infinite.
  • --echo (-e): echo the received messages to stdout. Default: enabled.
  • --no-echo (-ne): disable echoing received messages to stdout.
  • --recovery: enable recovery mode for TCP (only works with --mode=tcp). Default: off.
  • --recovery-queue-max-size <n>: maximum size of items (<n>) added to the recovery queue. Default: 1024.
  • --max-udp-packet-size: maximum size of udp packet; Default: unlimited.

Settings JSON File

The --settings switch can be used to specify a JSON file that contains a hash of settings for the application. A full settings file is:

  "address": "",
  "port": 514,
  "mode": "tcp",
  "secure": false,
  "noverify": false,
  "reconnect": true,
  "reconnectTries": 20,
  "echo": false

Note that command line switches take precedence over settings in a settings file. For example, given the settings file:

  "address": "",
  "port": 514

And the command line:

$ yes | pino-socket -s ./settings.json -p 1514

The connection will be made to address on UDP port 1514.


MIT License



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  • matteo.collina
  • jsumners
  • watson