README

VTFK Logger

A simple logger for node applications. Logs to console, papertrail (via token) and Azure Function.

Installation

npm install --save @vtfk/logger

Usage

Config

All options are optional.

Logging to papertrail can be configured in logConfig() or as env variables.

Azure Function logging can be configured in logConfing().

Note: logConfig() can be called multiple times to update the config throughout the program. And it will keep the previous config parameter if not specified in the next call.

const options = {
  remote: {                     // Options for remote logging. If undefined; disables remote logging
    disabled: false,            // If true; disables logging to remote, even if remote config is set
    onlyInProd: true,           // If true; only log to remote aggregator when NODE_ENV === 'production' (default is true)
    host: '',                   // Host for the remote aggregator
    token: ''                   // Token for the remote aggregator
  },
  azure: {                      // Options for Azure
    context: context,           // The context object received from an Azure Function (see example further down)
    excludeInvocationId: false  // If true; do not append the invocationId from the context object
  },
  prefix: '',                   // A string that will be added in front of each log message (ex. UID for each run)
  suffix: '',                   // A string that will be added at the end of each log message
  error: {                      // Options for logging out Error object. If undefined; stack from Error object will be returned
    useMessage: true            // If true; use message from Error object instead of stack
  },
  localLogger: console.log      // Replace the local logger with a custom function (Default: console.log)
}

logConfig(options)

ENV Variables

PAPERTRAIL_HOST = papertrail.example.com/v1/log
PAPERTRAIL_TOKEN = jvkuvuyoufyofo8ygo8f609fo7ouyvcio7=

logConfig() options take priority.

Examples

Ex. Basic

The least amount of code to log to console or a remote aggregator (if options are set in enviroment variables)

const { logger } = require('@vtfk/logger')

logger('info', ['test', 'message'])

Ex. Basic (async)

The least amount of code to log to console or a remote aggregator asynchronous (if options are set in enviroment variables)

const { logger } = require('@vtfk/logger')

await logger('info', ['test', 'message'])

Ex. Basic with specifying Error property

Use logConfig to instruct that message property is used from Error objects

const { logConfig, logger } = require('@vtfk/logger')

logConfig({
  error: {
    useMessage: true
  }
})

logger('info', ['test', 'message'])

logger('warn', ['another', 'action', new Error('Ups. Something happend')])

// OUTPUT 
// NAME-OF-APP and VER-OF-APP is the value of "name" and "version" in your package.json
[ 2019.05.19 15:41:17 ] < INFO >  {NAME-OF-APP} - {VER-OF-APP}: test - message
[ 2019.05.19 15:41:17 ] < WARN >  {NAME-OF-APP} - {VER-OF-APP}: another - action - Ups. Something happend

Ex. Basic without specifying Error property

const { logger } = require('@vtfk/logger')

logger('info', ['test', 'message'])

logger('warn', ['another', 'action', new Error('Ups. Something happend')])

// OUTPUT 
// NAME-OF-APP and VER-OF-APP is the value of "name" and "version" in your package.json
[ 2019.05.19 15:41:17 ] < INFO >  {NAME-OF-APP} - {VER-OF-APP}: test - message
[ 2019.05.19 15:41:17 ] < WARN >  {NAME-OF-APP} - {VER-OF-APP}: another - action - Error: Ups. Something happend\n

Ex. Basic with prefix

Use logConfig to display a UID infront of each message

const { logConfig, logger } = require('@vtfk/logger')
const nanoid = require('nanoid')

logConfig({
  prefix: nanoid()
})

logger('info', ['test', 'message'])

logger('warn', ['another', 'action'])

// OUTPUT 
// NAME-OF-APP and VER-OF-APP is the value of "name" and "version" in your package.json
[ 2019.05.19 15:41:17 ] < INFO >  {NAME-OF-APP} - {VER-OF-APP}: V01k3pDpHCBkAHPyCvOOl - test - message
[ 2019.05.19 15:41:17 ] < WARN >  {NAME-OF-APP} - {VER-OF-APP}: V01k3pDpHCBkAHPyCvOOl - another - action

Ex. Logging to remote

Configuration of remote options in the logConfig() function

const { logConfig, logger } = require('@vtfk/logger')

// logConfig() is optional
logConfig({
  remote: {
    onlyInProd: true,
    host: 'papertrail.example.com/v1/log',
    token: 'jvkuvuyoufyofo8ygo8f609fo7ouyvcio7=',
  }
  prefix: 'prefixedValue',
  suffix: 'suffixedValue'
})

logger('info', ['test', 'message'])

const error = Error('Error in process')
logger('error', ['Error in app', error])

// OUTPUT
// NAME-OF-APP and VER-OF-APP is the value of "name" and "version" in your package.json
[ 2019.05.19 15:13:35 ] < INFO >  {NAME-OF-APP} - {VER-OF-APP}: prefixedValue - test - message - suffixedValue
[ 2019.05.19 15:13:35 ] < ERROR >  {NAME-OF-APP} - {VER-OF-APP}: prefixedValue - Error in app - Error: Error in process - suffixedValue

Ex. Disable logging to remote