Logger for all Node.js modules by SEAL Systems

Usage no npm install needed!

<script type="module">
  import sealsystemsLog from 'https://cdn.skypack.dev/@sealsystems/log';



@sealsystems/log is the logger for all Node.js modules by SEAL Systems.

All log messages will be written to stdout and can then be processed by 3rd-party tools.


$ npm install @sealsystems/log

Quick start

First you need to integrate @sealsystems/log into your application.

const log = require('@sealsystems/log').getLogger();


The following log levels are defined:

  • debug:

    log.debug('This is a debug message.');
  • info:

    log.info('This is a info message.');
  • warn:

    log.warn('This is a warning message.');
  • error:

    log.error('This is a error message.');
  • fatal:

    log.fatal('This is a fatal error message.');

    Please note: This level will be used for logging an unhandled exception.

Uncaught exceptions/Unhandled rejections

Exceptions and rejections that are not caught otherwise are also logged with log level fatal. After logging the error, the process will be terminated with exit code 1. You have to require the log module at least one time in your project to enable this feature. No further configuration is required.

Environment Variables

Please note that when using mocha, all log-levels are always activated. See flaschenpost.


A list of log levels to print out. Possible levels are:

  • debug
  • info
  • warn
  • error
  • fatal

You have to provide a comma seperated list of the log levels you are interessted in:


The list given above is the default setting, if no environment variable is set.

You can enable all logging levels with the shortcut



A single minimum log level which includes all higher levels.


The setting above includes log levels warn, error and fatal.

The environment variable LOG_LEVEL has precedence over LOG_LEVELS.

Running the build

To build this module use roboter.

$ bot