tripitaka/lib/processors/human.js

A low dependency, no frills logger, designed to play nicely with tools like fluentd and Elasticsearch

const { EOL } = require('os');
const has = require('has-value');
const Chalk = require('chalk');
const stringify = require('json-stringify-safe');
const Level = require('../Level');

const DEFAULT_DECYCLER = () => {};

module.exports = (params = {}) => {
  const { serializer = null, indent = 2, decycler = DEFAULT_DECYCLER, colours } = params;
  const chalk = new Chalk.Instance({ level: colours });
  return ({ record }) => {
    const { level, timestamp = new Date(), message } = record;

    const timestampText = chalk.underline(timestamp.toISOString().replace(/T/, ' ').replace(/\..+/, ''));

    let levelText;

    switch (Level.lookup(level)) {
      case Level.ERROR: {
        levelText = chalk.redBright(level);
        break;
      }
      case Level.WARN: {
        levelText = chalk.yellow(level.padEnd(5));
        break;
      }
      default: {
        levelText = chalk.green(level.padEnd(5));
      }
    }

    let msg = `${timestampText} ${levelText} ${message}`;

    const ctx = {};
    for (const [key, value] of Object.entries(record)) {
      if (has(value, 'stack')) msg += `${EOL}${value.stack}`;
      else if (['timestamp', 'level', 'message'].includes(key)) continue;
      else {
        ctx[key] = value;
      }
    }
    if (Object.keys(ctx).length > 0) {
      const contextText = stringify(ctx, serializer, indent, decycler);
      msg += `${EOL}${contextText}`;
    }
    return msg;
  };
};