chip-log

• Installation
• • General Logger
• • Express Logging
• Levels
• Configuration
• Debug Wrapping
• Middleware
• • Context
• • Request
• Example Application

Chip-log provides NodeJS with structured logging which includes extended attributes

• module, function name, and line number of the caller
• requestId pulled from async hook in the request (express)
• request logging (express)
• wrapper for Debug for faster debug logs

# Examples below using pino-pretty as formatter

[1611629195127] INFO (17914 on evil.lan): nested
    module: "example-appserver"
    function: "nestedHandler"
    lineNum: 6
    requestId: "10279b7c-69fe-4767-b36a-80f6b0b2266c"
    payload: {
      myData: "example payload"
    }
[1611629195128] INFO (17914 on evil.lan): finished
    module: "example-appserver"
    function: "helloWorldHandler"
    lineNum: 12
    requestId: "10279b7c-69fe-4767-b36a-80f6b0b2266c"

Installation

Requirements

• NodeJS 14+
• [optional] Express v4+

Use as a general purpose logger

Import chip-log and call the log level with a message, a json object, or both

const log = require('chip-log');

log.info('hello world')
log.error(err.message, { error })

Use with Express

See example-app below, or the Chip-Log Repo on Github

Log Levels

• error
• warn
• info
• debug
• trace
• fatal
• silent

Configuration

Envars to configure

Minimum log level to dispatch, default: info

LOG_LEVEL=trace|debug|info|warn|error|fatal

Namespace for the async hook context, default: APP_NAMESPACE

APP_NAMESPACE=My_Application

Path to the entry directory of the application (defaults to current working directory the node process is started in)

APP_BASE=./src

Disable logging, like during tests

LOG_VOID=true

Redacting specific paths in logs

REDACT='req.body.password,req.params.password

Debug Wrapping

To wrap debug messages provided from Debug, ensure Chip-Log is the first import of the entry file for your module.

Middleware

requires Express v4+

Context Middleware

Using NodeJS Async Hooks, attach a Request ID to a request. When logging in a function as part of a Express request, the requestId will be one of the attributes on the log

In your application setup for express, when declaring middleware .use(), aim to add the context middleware as close to being first as possible.

const app = require('express')()
const { context } = require('chip-log').middleware;

app.use(context())

# example output using pino-pretty

[1611629195128] INFO (17914 on evil.lan): finished
    module: "example-appserver"
    function: "helloWorldHandler"
    lineNum: 12
    requestId: "10279b7c-69fe-4767-b36a-80f6b0b2266c"

Request Middleware

Provides details of the request and response from Express for a request. If used with Context middleware, the log will also contain the requestId

In your application setup for express, when declaring middleware .use(), you can place request anywhere before routes are declared. If using with the Context middleware, place anywhere after, before the routes

const app = require('express')()
const { context, request } = require('chip-log').middleware;

app.use(context())
app.use(request())

# example output using pino-pretty

[1612893183539] INFO (25216 on RR3D-MAC0005.lan): request completed
    req: {
      "id": "8c276c5d-2717-47b5-8dbf-c4d33964e057",
      "method": "GET",
      "url": "/favicon.ico",
      "headers": {
        "host": "localhost:3000",
        "connection": "keep-alive",
        "sec-ch-ua": "\"Google Chrome\";v=\"87\", \" Not;A Brand\";v=\"99\", \"Chromium\";v=\"87\"",
        "sec-ch-ua-mobile": "?0",
        "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 11_2_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36",
        "accept": "image/avif,image/webp,image/apng,image/*,*/*;q=0.8",
        "sec-fetch-site": "same-origin",
        "sec-fetch-mode": "no-cors",
        "sec-fetch-dest": "image",
        "referer": "http://localhost:3000/",
        "accept-encoding": "gzip, deflate, br",
        "accept-language": "en-US,en;q=0.9"
      },
      "remoteAddress": "::1",
      "remotePort": 50622
    }
    requestId: "8c276c5d-2717-47b5-8dbf-c4d33964e057"
    res: {
      "statusCode": 404,
      "headers": {
        "x-powered-by": "Express",
        "content-security-policy": "default-src 'none'",
        "x-content-type-options": "nosniff",
        "content-type": "text/html; charset=utf-8",
        "content-length": 150
      }
    }
    responseTime: 2

Example Application

const app = require('express')()
const log = require('chip-log')

const {
  context,
  request,
} = log.middleware

const nestedHandler = () => {
  log.info('nested')
}

const helloWorldHandler = (req, res) => {
  nestedHandler()

  log.info('finished', { test: 'one' })
  res.send('Hello world')
}

app.use(context())
app.use(request())
app.get('/', helloWorldHandler)

app.listen(3000, () => log.info('Running'))