direct-logger

direct-logger

based on https://github.com/wesleytodd/loggerr

Logger call API is interoperable with pino logger.

Features:

• Synchronous output (great for cli's, browser and tools)
• Levels (built-in and customizable)
• Formatting (built-in and customizable)
• direct-logger is dependency free (formatters are not)
• Always captures stack trace on error logs
• Tiny filesize
• The cli formatter 🚀

Install

$ yarn add direct-logger

Usage

const { Logger } = require('direct-logger')
const logger = Logger()

logger.error(new Error('My error message'))
// Thu Apr 16 2015 22:05:27 GMT-0500 (CDT) [error] - {"msg":"Error: My error message\n<STACK TRACE>"}

logger.info('Something happened', {
  foo: 'info about what happened'
})
// Thu Apr 16 2015 22:05:27 GMT-0500 (CDT) [info] - {"msg":"Something happened","foo":"info about what happened"}

Log Levels

Each log level can be directed to a different output stream or disabled entirely. The default levels are as follows:

• fatal
• error
• warn (default)
• info
• debug
• trace

Constants are available for setting and referencing the levels and their streams. These constants are the all uppercase version of the level. Here is an example of setting the log level:

const logger = Logger({
  level: Logger.DEBUG
})

logger.debug('Foo')
// Thu Apr 16 2015 22:05:27 GMT-0500 (CDT) [debug] - {"msg":"Foo"}

Customize Levels

You can fully customize the levels for your purposes. For example, here we implement pino compatible levels:

const log = Logger({
  level: [ 'trace', 'debug', 'info', 'warn', 'error', 'fatal' ]
})

log.trace('Example trace log')

Log Formatting

direct-logger supports formatting via formatter functions. The default formatter outputs a timestamp, the log level and the messages formatted as json. But you can provide a custom formatter function with the formatter options. Formatter functions take three parameters: date, level, data. Say we want to output the log message with a color based on the level:

const Logger = require('direct-logger')
const chalk = require('chalk')

const logger = Logger({
  formatter: (date, level, data) => {
    var color
    switch (Logger.levels.indexOf(level)) {
      case Logger.FATAL:
      case Logger.ERROR:
        color = chalk.red
        break
      case Logger.WARN:
        color = chalk.yellow
        break
      case Logger.INFO:
      case Logger.DEBUG:
        color = chalk.white
        break
    }
    return color(data.msg)
  }
})

There are a few built-in in formatters:

• default: Outputs date, level and json
• cli: Outputs the message and json data, colorized and formatted
• bunyan: Compatible format to bunyan
• browser: Relies on console.log, so just returns the data

For these built-in formatters can specify the string name of the formatter for built-in formatters:

const log = Logger({
  formatter: 'cli'
})

To use the cli formatter you can require it and pass the formatter options:

const log = Logger({
  formatter: require('direct-logger/formatters/cli')
})

Output Streams

You can output each level to it's own stream. The method is simple, just pass an array of streams corresponding to each level as the streams option. The simplest way is to just map over Logger.levels, this is how we set the defaults:

Logger({
  streams: Logger.levels.map(function (level, i) {
    return i > Logger.WARN ? process.stdin : process.stderr
  })
})

The most useful reason to specify an output stream to to redirect logs to files. Here is an example of how to do that:

const logfile = fs.createWriteStream('./logs/stdout.log', {
  flags: 'a',
  encoding: 'utf8'
})

Logger({
  streams: Logger.levels.map(() => logfile)
})

Redact secrets

const logger = Logger({
  secrets: ["1234"],
  secretsHideCharsCount: false, // default false
  secretsStringSubstition: "***", // used when secretsHideCharsCount is true
  secretsRepeatCharSubstition: "*", // used when secretsHideCharsCount is false
})

logger.info("secret is 123454678") // output "secret is ****5678"

logger.addSecret("5678")
logger.secretsHideCharsCount = true
logger.info("secret is 123454678") // output "secret is ***"

logger.deleteSecret("1234")
logger.info("secret is 123454678") // output "secret is 1234***"

const hasSecret = logger.hasSecret("54678") // hasSecret === true

Arguments order

Arguments orders are reversible.

// classical
logger.debug("Hello world !", { foo: "bar" })

// pino compatible
logger.debug({ foo: "bar" }, "Hello world !")

// string message can be replaced by object having a `toString` method
logger.debug({ foo: "bar" }, new Error("Here is a message"))
logger.debug(new Error("Here is another message"), { foo: "bar" })

Set Level

logger.setLevel("warn")
logger.minLevel("debug")
logger.maxLevel("info")

Changelog

2.15.1 (2023-05-07)

Bug Fixes

• relay dateStart to children logger + lint (67d40d7)