@logtail/node

🪵 Logtail - Node.js logging

New to Logtail? Here's a low-down on logging in JavaScript.

@logtail/node

This NPM library is for logging in Node.js.

If you have a universal or client-side app that requires logging in the browser, check out @logtail/browser or @logtail/js (which combines the two packages.)

Here's how to get started:

Installation

Install the package directly from NPM:

npm i @logtail/node

Importing

In ES6/Typescript, import the Logtail class:

import { Logtail } from "@logtail/node";

For CommonJS, require the package:

const { Logtail } = require("@logtail/node");

Creating a client

Simply pass your Logtail.com source access token as a parameter to a new Logtail instance (you can grab it from Logtail.com):

const logtail = new Logtail("logtail-access-token");

Documentation

This Node.js library extends @logtail/core, which provides a simple API for logging, adding middleware and more.

Visit the relevant readme section for more info/how-to:

• Logging
• Middleware

Streaming

In addition to .log|debug|info|warn|error() returning a Promise, the Node.js logger offers a .pipe() function for piping successfully synchronized logs to any writable stream.

This makes it trivial to additionally save logs to a file, stream logs over the network, or interface with other loggers that accept streamed data.

Here's a simple example of saving logs to a logs.txt file:

// Import the Node.js `fs` lib
import * as fs from "fs";

// Import the Node.js Logtail library
import { Logtail } from "@logtail/node";

// Open a writable stream to `logs.txt`
const logsTxt = fs.createWriteStream("./logs.txt");

// Create a new Logtail instance, and pipe output to `logs.txt`
const logtail = new Logtail("logtail-access-token");
logtail.pipe(logsTxt);

// When you next log, `logs.txt` will get a JSON string copy
logtail.log("This will also show up in logs.txt");

Streamed logs passed to your write stream's .write() function will be JSON strings in the format of type ILogtailLog, and always contain exactly one complete log after it has been transformed by middleware and synced with Logtail.com.

e.g:

{"dt":"2018-12-29T08:38:33.272Z","level":"info","message":"message 1"}

If you want to further process logs in your stream, remember to JSON.parse(chunk.toString()) the written 'chunk', to turn it back into an ILogtailLog object.

Calls to .pipe() will return the passed writable stream, allowing you to chain multiple .pipe() operations or access any other stream function:

// Import a 'pass-through' stream, to prove it works
import { PassThrough } from "stream";

// This stream won't do anything, except copy input -> output
const passThroughStream = new PassThrough();

// Passing to multiple streams works...
logtail.pipe(passThroughStream).pipe(logsTxt);

LICENSE

ISC