index.js

/* @flow */
const winston = require('winston')
const path = require('path')

/**
 * creates new custom winston logger
 *
 * @param {object} config - koop configuration
 * @return {Logger} custom logger instance
 */
function createLogger (config) {
  config = config || {}
  let level
  if (process.env.KOOP_LOG_LEVEL) {
    level = process.env.KOOP_LOG_LEVEL
  } else if (process.env.NODE_ENV === 'production') {
    level = 'info'
  } else {
    level = 'debug'
  }

  if (!config.logfile) {
    // no logfile defined, log to STDOUT an STDERRv
    const debugConsole = new winston.transports.Console({
      colorize: process.env.NODE_ENV === 'production',
      level,
      stringify: true,
      json: true
    })
    return winston.createLogger({ transports: [debugConsole] })
  }

  // we need a dir to do log rotation so we get the dir from the file
  const logpath = path.dirname(config.logfile)
  const logAll = new winston.transports.File({
    filename: config.logfile,
    name: 'log.all',
    dirname: logpath,
    colorize: true,
    json: false,
    level,
    formatter: formatter
  })
  const logError = new winston.transports.File({
    filename: config.logfile.replace('.log', '.error.log'),
    name: 'log.error',
    dirname: logpath,
    colorize: true,
    json: false,
    level: 'error',
    formatter: formatter
  })

  // always log errors
  const transports = [logError]
  // only log everthing if debug mode is on
  if (process.env.LOG_LEVEL === 'debug') {
    transports.push(logAll)
  }

  return winston.createLogger({ transports })
}

/**
 * formats winston log lines
 * @param {object} options - log info from winston
 * @return {string} formatted log line
 */
function formatter (options) {
  const line = [
    new Date().toISOString(),
    options.level
  ]

  if (options.message !== undefined) line.push(options.message)

  if (options.meta && Object.keys(options.meta).length) line.push(JSON.stringify(options.meta))

  return line.join(' ')
}

module.exports = createLogger