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 = () => undefined;
   7
   8 class Logger {
   9   /**
  10    * @callback LogFn
  11    * @param {any} ...args values to log
  12    * @returns {void} nothing
  13    */
  14   /**
  15    * @typedef {object} ConsoleLike
  16    * @property {LogFn} error error level
  17    * @property {LogFn} warn warn level
  18    * @property {LogFn} info info level
  19    * @property {LogFn} log log level
  20    * @property {LogFn} debug debug level
  21    */
  22   /**
  23    * @typedef AsyncLocalStorage
  24    * @property {Function} getStore local storage
  25    */
  26   /**
  27    * @typedef {object} LoggerOptions
  28    * @property {string} ignoreBelowLevel minimum level to log, e.g. 'info'
  29    */
  30   /**
  31    * Wrap backend calls with payload normalization and metadata.
  32    * @param {LoggerOptions} options options
  33    * @param {object} commonObject object to be merged into logged json
  34    * @param {AsyncLocalStorage} asyncLocalStorage async storage for an object to be merged into logged json
  35    * @param {ConsoleLike} backend default is console
  36    */
  37   constructor(options, commonObject, asyncLocalStorage, backend) {
  38     const logLevels = Object.keys(Logger.nullLogger);
  39     const ignoreBelowLevel = options?.ignoreBelowLevel || 'debug';
  40     this.backend = backend || console;
  41     this.commonObject = commonObject || {};
  42     this.jsonReplacers = Object.values(jsonReplacers);
  43     this.dataSanitizers = Object.values(dataSanitizers);
  44
  45     if (asyncLocalStorage) {
  46       // Override the class getter.
  47       Object.defineProperty(this, 'asyncLogObject', {
  48         enumerable: true,
  49         get: asyncLocalStorage.getStore.bind(asyncLocalStorage),
  50       });
  51     }
  52
  53     if (!logLevels.includes(ignoreBelowLevel)) {
  54       throw new RangeError(`unrecognized minimum log level '${ignoreBelowLevel}'`);
  55     }
  56     const ignoreLevelIdx = logLevels.indexOf(ignoreBelowLevel);
  57     logLevels.forEach((level) => {
  58       const includeBackendLevel = (logLevels.indexOf(level) > ignoreLevelIdx) && this.backend[level]; // eslint-disable-line security/detect-object-injection
  59       // eslint-disable-next-line security/detect-object-injection
  60       this[level] = (includeBackendLevel) ?
  61         nop :
  62         (...args) => this.backend[level](this.payload(level, ...args)); // eslint-disable-line security/detect-object-injection
  63     });
  64   }
  65
  66
  67   /**
  68    * All the expected Console levels, but do nothing.
  69    * Ordered from highest priority to lowest.
  70    * @returns {object} no-op backend
  71    */
  72   static get nullLogger() {
  73     return {
  74       error: nop,
  75       warn: nop,
  76       info: nop,
  77       log: nop,
  78       debug: nop,
  79     };
  80   }
  81
  82
  83   /**
  84    * Default of empty object when no asyncLocalStorage is defined.
  85    * Overridden on instance when asyncLocalStorage is defined.
  86    * @returns {object} empty
  87    */
  88   // eslint-disable-next-line class-methods-use-this
  89   get asyncLogObject() {
  90     return {};
  91   }
  92
  93
  94   /**
  95    * Structure all expected log data into JSON string.
  96    * @param {string} level log level
  97    * @param {string} scope scope
  98    * @param {string} message message
  99    * @param {object} data data
 100    * @param  {...any} other more data merged into payload
 101    * @returns {string} JSON string
 102    */
 103   payload(level, scope, message, data, ...other) {
 104     const replacer = this.getReplacer();
 105
 106     if (this.sanitizationNeeded(data)) {
 107       // Create copy of data so we are not changing anything important.
 108       try {
 109         data = structuredClone(data);
 110       } catch (e) { // eslint-disable-line no-unused-vars
 111         data = JSON.parse(JSON.stringify(data, replacer));
 112       }
 113       this.sanitize(data);
 114     }
 115
 116     const now = new Date();
 117     const logPayload = {
 118       ...this.commonObject,
 119       timestamp: now.toISOString(),
 120       timestampMs: now.getTime(),
 121       level: level,
 122       scope: scope || '[unknown]',
 123       message: message || '',
 124       data: data || {},
 125       ...(other.length && { other }),
 126       ...this.asyncLogObject,
 127     };
 128     return JSON.stringify(logPayload, replacer);
 129   }
 130
 131
 132   /**
 133    * Determine if data needs sanitizing.
 134    * @param {object} data data
 135    * @returns {boolean} needs sanitization
 136    */
 137   sanitizationNeeded(data) {
 138     return this.dataSanitizers.some((sanitizer) => sanitizer(data, false));
 139   }
 140
 141
 142   /**
 143    * Mogrify data.
 144    * @param {object} data data
 145    */
 146   sanitize(data) {
 147     this.dataSanitizers.forEach((sanitizer) => sanitizer(data));
 148   }
 149
 150
 151   /**
 152    * Return a replacer function which does de-cycling, as well as the rest of our replacers.
 153    * @returns {Function} replacer
 154    */
 155   getReplacer() {
 156     const ancestors = [];
 157     const loggerReplacers = this.jsonReplacers;
 158     return function cycleReplacer(key, value) {
 159       loggerReplacers.every((replacer) => {
 160         const oldValue = value;
 161         value = replacer(key, value);
 162         return oldValue === value;
 163       });
 164       if (typeof value === 'object' && value !== null) {
 165         // 'this' is object where key/value came from
 166         while (ancestors.length > 0 && ancestors.at(-1) !== this) {
 167           ancestors.pop();
 168         }
 169         if (ancestors.includes(value)) {
 170           return '[Circular]';
 171         } else {
 172           ancestors.push(value);
 173         }
 174       }
 175
 176       return value;
 177     };
 178   }
 179
 180 }
 181
 182 module.exports = Logger;