git.squeep.com Git - squeep-logger-json-console/blob - lib/logger.js

   1 'use strict';
   2
   3 const jsonReplacers = require('./json-replacers');
   4 const dataSanitizers = require('./data-sanitizers');
   5
   6 /**
   7  * Log as JSON to stdout/stderr.
   8  */
   9
  10 const nop = () => { /**/ };
  11
  12
  13 class Logger {
  14   /**
  15    * Wrap backend calls with payload normalization.
  16    * @param {Object} options
  17    * @param {String} options.nodeId - unique identifier for running instance, usually a uuid
  18    * @param {Object} options.logger
  19    * @param {String} options.logger.ignoreBelowLevel - minimum level to log
  20    */
  21   constructor(options) {
  22     const logLevels = Object.keys(Logger.nullLogger);
  23     const ignoreBelowLevel = options && options.logger && options.logger.ignoreBelowLevel || 'debug';
  24     this.backend = console;
  25     this.nodeId = options.nodeId;
  26     this.jsonReplacers = Object.values(jsonReplacers);
  27     this.dataSanitizers = Object.values(dataSanitizers);
  28
  29     if (!logLevels.includes(ignoreBelowLevel)) {
  30       throw new RangeError(`unrecognized minimum log level '${ignoreBelowLevel}'`);
  31     }
  32     const ignoreLevelIdx = logLevels.indexOf(ignoreBelowLevel);
  33     logLevels.forEach((level) => {
  34       // eslint-disable-next-line security/detect-object-injection
  35       this[level] = (logLevels.indexOf(level) > ignoreLevelIdx) ?
  36         nop :
  37         (...args) => this.backend[level](this.payload(level, ...args)); // eslint-disable-line security/detect-object-injection
  38     });
  39   }
  40
  41
  42   /**
  43    * All the expected Console levels, but do nothing.
  44    * Ordered from highest priority to lowest.
  45    */
  46   static get nullLogger() {
  47     return {
  48       error: nop,
  49       warn: nop,
  50       info: nop,
  51       log: nop,
  52       debug: nop,
  53     };
  54   }
  55
  56
  57   /**
  58    * Structure all expected log data into JSON string.
  59    * @param {String} level
  60    * @param {String} scope
  61    * @param {String} message
  62    * @param {Object} data
  63    * @param  {...any} other
  64    * @returns {String} JSON string
  65    */
  66   payload(level, scope, message, data, ...other) {
  67     if (this.sanitizationNeeded(data)) {
  68       // Create copy of data so we are not changing anything important.
  69       data = JSON.parse(JSON.stringify(data, this.jsonReplacer.bind(this)));
  70       this.sanitize(data);
  71     }
  72
  73     const now = new Date();
  74     return JSON.stringify({
  75       nodeId: this.nodeId,
  76       timestamp: now.toISOString(),
  77       timestampMs: now.getTime(),
  78       level: level,
  79       scope: scope || '[unknown]',
  80       message: message || '',
  81       data: data || {},
  82       ...(other.length && { other }),
  83     }, this.jsonReplacer.bind(this));
  84   }
  85
  86
  87   /**
  88    * Determine if data needs sanitizing.
  89    * @param {Object} data
  90    * @returns {Boolean}
  91    */
  92   sanitizationNeeded(data) {
  93     return this.dataSanitizers.some((sanitizer) => sanitizer(data, false));
  94   }
  95
  96
  97   /**
  98    * Mogrify data.
  99    * @param {Object} data
 100    */
 101   sanitize(data) {
 102     this.dataSanitizers.forEach((sanitizer) => sanitizer(data));
 103   }
 104
 105
 106   /**
 107    * Convert data into JSON.
 108    * @param {String} _key
 109    * @param {*} value
 110    * @returns {String} serialized value
 111    */
 112   jsonReplacer(key, value) {
 113     let replaced;
 114
 115     // Try applying all our replacers, until one does something.
 116     this.jsonReplacers.every((replacer) => {
 117       ({ replaced, value } = replacer(key, value));
 118       return !replaced;
 119     });
 120     return value;
 121   }
 122
 123 }
 124
 125 module.exports = Logger;