pino-seq

A stream to send Pino events to Seq. Tested with Node.js versions 18.x and up.

Now written in TypeScript with automatic type definitions and full ES Module support!

Installation

npm install pino-seq

Usage

Use the createStream() method to create a Pino stream configuration, passing serverUrl, apiKey and batching parameters.

This example works in both JavaScript and TypeScript projects:

import pino from 'pino';
import { createStream } from 'pino-seq';

// Create a stream to Seq
const stream = createStream({ 
  serverUrl: 'http://localhost:5341',
  apiKey: 'your-api-key' // optional
});

// Create a Pino logger
const logger = pino({ name: 'pino-seq example' }, stream);

// Log some messages
logger.info('Hello Seq, from Pino');

// Child loggers work too
const frLogger = logger.child({ lang: 'fr' });
frLogger.warn('au reviour');

// Flush logs before exit
await stream.flush();

For TypeScript projects with explicit typing:

import { createStream, PinoSeqStreamConfig } from 'pino-seq';

const config: PinoSeqStreamConfig = {
  serverUrl: 'http://localhost:5341',
  // ... see Configuration section below for all options
};
const stream = createStream(config);

Configuration

The createStream() function accepts a configuration object with the following properties:

• serverUrl (string): The URL of your Seq server
• apiKey (string, optional): API key for authentication
• logOtherAs (string, optional): Log level for unstructured messages ('Verbose', 'Debug', 'Information', 'Warning', 'Error', 'Fatal')
• additionalProperties (object, optional): Additional properties to add to all log events
• maxBatchingTime (number, optional): Maximum time in milliseconds to wait before sending a batch
• eventSizeLimit (number, optional): Maximum size of a single event
• batchSizeLimit (number, optional): Maximum size of a batch
• onError (function, optional): Error handler callback

Development

Running Tests

The test suite includes:

• Integration tests that verify round-trip logging to Seq by querying the API
• Example tests that verify examples work as users would use them (via npm link)

With local Seq instance (recommended - tests actual integration):

# Start Seq container (with health check)
npm run test:setup

# Run tests (includes TypeScript compilation and example verification)
npm test

# Stop Seq
npm run test:teardown

Without Seq (type checking only):

npm run build  # Just compiles TypeScript

Running the Example

# Start Seq
npm run test:setup

# Run the example
npm start

# View logs at http://localhost:5341

# Stop Seq
npm run test:teardown

Building

npm run build

The build uses the TypeScript compiler (tsc) to produce ES Module output in the dist/ directory with automatic type definitions.

Note: This package is ESM-only (like its dependency seq-logging). If you need CommonJS support, please use version 2.x or earlier.

Acknowledgements

Originally by Simi Hartstein and published as simihartstein/pino-seq; maintainership transferred to Datalust at version 0.5.