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 const nop = () => { /**/ };
   7
   8 class Logger {
   9   /**
  10    * @typedef {Object} ConsoleLike
  11    * @property {Function(...):void} error
  12    * @property {Function(...):void} warn
  13    * @property {Function(...):void} info
  14    * @property {Function(...):void} log
  15    * @property {Function(...):void} debug
  16    */
  17   /**
  18    * @typedef {Object} LoggerOptions
  19    * @property {String} ignoreBelowLevel - minimum level to log, e.g. 'info'
  20    */
  21   /**
  22    * Wrap backend calls with payload normalization and metadata.
  23    * @param {LoggerOptions} options
  24    * @param {Object} commonObject - object to be merged into logged json
  25    * @param {AsyncLocalStorage} asyncLocalStorage - async storage for an object to be merged into logged json
  26    * @param {ConsoleLike} backend - default is console
  27    */
  28   constructor(options, commonObject, asyncLocalStorage, backend) {
  29     const logLevels = Object.keys(Logger.nullLogger);
  30     const ignoreBelowLevel = options?.ignoreBelowLevel || 'debug';
  31     this.backend = backend || console;
  32     this.commonObject = commonObject || {};
  33     this.jsonReplacers = Object.values(jsonReplacers);
  34     this.dataSanitizers = Object.values(dataSanitizers);
  35
  36     if (asyncLocalStorage) {
  37       // Override the class getter.
  38       Object.defineProperty(this, 'asyncLogObject', {
  39         enumerable: true,
  40         get: asyncLocalStorage.getStore.bind(asyncLocalStorage),
  41       });
  42     }
  43
  44     if (!logLevels.includes(ignoreBelowLevel)) {
  45       throw new RangeError(`unrecognized minimum log level '${ignoreBelowLevel}'`);
  46     }
  47     const ignoreLevelIdx = logLevels.indexOf(ignoreBelowLevel);
  48     logLevels.forEach((level) => {
  49       const includeBackendLevel = (logLevels.indexOf(level) > ignoreLevelIdx) && this.backend[level]; // eslint-disable-line security/detect-object-injection
  50       // eslint-disable-next-line security/detect-object-injection
  51       this[level] = (includeBackendLevel) ?
  52         nop :
  53         (...args) => this.backend[level](this.payload(level, ...args)); // eslint-disable-line security/detect-object-injection
  54     });
  55   }
  56
  57
  58   /**
  59    * All the expected Console levels, but do nothing.
  60    * Ordered from highest priority to lowest.
  61    */
  62   static get nullLogger() {
  63     return {
  64       error: nop,
  65       warn: nop,
  66       info: nop,
  67       log: nop,
  68       debug: nop,
  69     };
  70   }
  71
  72
  73   /**
  74    * Default of empty object when no asyncLocalStorage is defined.
  75    * Overridden on instance when asyncLocalStorage is defined.
  76    */
  77   // eslint-disable-next-line class-methods-use-this
  78   get asyncLogObject() {
  79     return {};
  80   }
  81
  82
  83   /**
  84    * Structure all expected log data into JSON string.
  85    * @param {String} level
  86    * @param {String} scope
  87    * @param {String} message
  88    * @param {Object} data
  89    * @param  {...any} other
  90    * @returns {String} JSON string
  91    */
  92   payload(level, scope, message, data, ...other) {
  93     if (this.sanitizationNeeded(data)) {
  94       // Create copy of data so we are not changing anything important.
  95       data = JSON.parse(JSON.stringify(data, this.jsonReplacer.bind(this)));
  96       this.sanitize(data);
  97     }
  98
  99     const now = new Date();
 100     return JSON.stringify({
 101       ...this.commonObject,
 102       timestamp: now.toISOString(),
 103       timestampMs: now.getTime(),
 104       level: level,
 105       scope: scope || '[unknown]',
 106       message: message || '',
 107       data: data || {},
 108       ...(other.length && { other }),
 109       ...this.asyncLogObject,
 110     }, this.jsonReplacer.bind(this));
 111   }
 112
 113
 114   /**
 115    * Determine if data needs sanitizing.
 116    * @param {Object} data
 117    * @returns {Boolean}
 118    */
 119   sanitizationNeeded(data) {
 120     return this.dataSanitizers.some((sanitizer) => sanitizer(data, false));
 121   }
 122
 123
 124   /**
 125    * Mogrify data.
 126    * @param {Object} data
 127    */
 128   sanitize(data) {
 129     this.dataSanitizers.forEach((sanitizer) => sanitizer(data));
 130   }
 131
 132
 133   /**
 134    * Convert data into JSON.
 135    * @param {String} _key
 136    * @param {*} value
 137    * @returns {String} serialized value
 138    */
 139   jsonReplacer(key, value) {
 140     let replaced;
 141
 142     // Try applying all our replacers, until one does something.
 143     this.jsonReplacers.every((replacer) => {
 144       ({ replaced, value } = replacer(key, value));
 145       return !replaced;
 146     });
 147     return value;
 148   }
 149
 150 }
 151
 152 module.exports = Logger;