@sugo/logger

Plugin based logger to be used in multiple applications. It's philosophy is to be a 'glue' or 'container' for different types of plugins that do all the hard work. The Logger creates the log date and the message to be logged and gives them to the plugins.

Requirements

node version >= 9.11.2

How to install

npm install --save @sugo/logger

Logger

Base object to which the plugins will be attached.

options

• level: Log level to which to write logs. It follows the Log4J rules for levels. All levels have a numeric value associated to them, if the logger level is higher than a requested level, it will not be logged. This module contains a levels object to help readability when assigning levels.

{
  "ALL": 0,
  "TRACE": 1,
  "DEBUG": 2,
  "INFO": 3,
  "WARN": 4,
  "ERROR": 5,
  "FATAL": 6,
  "OFF": 7
}

import { Logger } from '@sugo/logger';
import { ConsoleLoggerPlugIn } from '@sugo/logger/plugins/console';
import { ElasticSearchRestLoggerPlugIn } from '@sugo/logger/plugins/elasticSearchRest';
import { FileLoggerPlugIn } from '@sugo/logger/plugins/file';

import { Logger, levels } from '../logger';
import { ConsoleLoggerPlugIn } from '../plugins';
// It will only print FATAL logs
const logger = new Logger({ level: levels.FATAL, plugins: [new ConsoleLoggerPlugIn()] });

• transports: Color to be used for the log tag in the trace method.

Methods:

• addPlugin(plugin)

• trace(message, date)

• debug(message, date)

• info(message, date)

• warn(message, date)

• error(message, date)

• fatal(message, date)

NOTE: All logging methods are asynchronous to reduce the logger performance impact.

ConsoleLoggerPlugIn

A simple logger that logs to the console. Has a default color scheme that can be customtized. The exportd colors object contains the different colors that can be assigned.

options

• resetColor: Default text color.

• traceColor: Color to be used for the log tag in the trace method.

• debugColor: Color to be used for the debug tag in the debug method.

• infoColor: Color to be used for the debug tag in the info method.

• warnColor: Color to be used for the warn tag in the warn method.

• errorColor: Color to be used for the error tag in the error method.

• fatalColor: Color to be used for the error tag in the fatal method.

const { ConsoleLoggerPlugIn, colors } = require('@sugo/logger/plugins/console');
const consolePlugin = new ConsoleLoggerPlugIn({
  infoColor: colors.FgBlack,
});

ElasticSearchRestLoggerPlugIn

Logs to an elastic search index.

this.host = options.host || "http://localhost"; this.port = options.port || 9200; this.index = options.index; this.type = options.type || "logs";

options

• host: Elastic search server host url. Default: http://localhost.

• port: Elastic search server port. Default: 9200.

• index: Elastic search index name. Required.

• type: Elastic search mapping type. Default: 'logs'.

FileLoggerPlugIn

Logs to a file. Can be set to log to a different file daily.

options

• path: The path where the logs will be created. Default: './logs/'.

• filename: The name of the file. Default: 'log.txt'.

• daily: Boolean that defines if there must be a file for each day. If set to true then it will append the date to the filename name. Example 'logs-28-10-1991.txt Default: false.

Writing a Custom Plugin

To write a custom plugin, just create an object that implementes the following methods:

• trace(message, date)

• debug(message, date)

• info(message, date)

• warn(message, date)

• error(message, date)

• fatal(message, date)

NOTE 1: The message and date will be passed down from the Logger object.

NOTE 2: As the logger is not meant to stop the execution of most applications, a handleError(err) method that captures all errors is recommended.

Complete Application Example

import { Logger } from '@sugo/logger';
import { ConsoleLoggerPlugIn } from '@sugo/logger/plugins/console';
import { ElasticSearchRestLoggerPlugIn } from '@sugo/logger/plugins/elasticSearchRest';
import { FileLoggerPlugIn } from '@sugo/logger/plugins/file';

const logger = new Logger();
const consolePlugin = new ConsoleLoggerPlugIn();
const elasticPlugin = new ElasticSearchRestLoggerPlugIn({
  host: 'http://localhost',
  port: 9200,
  index: 'sugo-logger-test',
  type: 'logs',
});
const filePlugin = new FileLoggerPlugIn({
  path: './logs/',
  filename: 'test.log',
  daily: true,
});
logger
  .addPlugin(consolePlugin)
  .addPlugin(elasticPlugin)
  .addPlugin(filePlugin);

logger.trace('Hello', 'World');
logger.debug('Hello', 'World');
logger.info('Hello', 'World');
logger.warn('Hello', 'World');
logger.error('Hello', 'World');
logger.fatal('Hello', 'World');