README

@cisl/logger

This is a NPM module that wraps around the winston logging library to take advantage of the cog.json file for configuration. This allows for easier usage within cogs as it does not require knowing the boilerplate of using winston and the parts of the cog.json. This is largely compatible with the existing function/usage of @cel/logger.

Installation

npm install @cisl/logger

Usage

const logger = require('@cisl/logger');
logger.debug('debug');
logger.verbose(1);
logger.info('info');
logger.warn({test: 'aaaa', foo: 'bar'});
logger.error('error');
logger.setLogLevel('warn');
logger.logExpression('some message', 'info');
logger.logExpression('some error', 0);

Note: For logging throw exceptions, you should either cast it to a string (e.g. logger.info(`${new Error('test')}`))) or pass specific parts of the exception as strings:

const err = new Error('test');
logger.error(err.message);
logger.error(err.stack);

Attempting to log the Error object as-is will end up with just logging undefined.

Configuration

As stated above, the logger uses the cog.json file in the current working directory to configure itself. By default, the logger will always log to console and be set to a level of info. This can be tuned, as well as adding additional transports, by adding a logging block to the cog.json, using the following keys:

{
  logging: {
    info: "level" // String specifying level to log at, defaults to 'info'
    console: true | false // Boolean flag to turn on/off console logging, defaults to true.
    file: "filename" // string for file to write log to
    db: true | false // Boolean flag to turn on/off logging to MongoDB, defaults to false
  }
}

If no cog.json exists, then it uses a default of log level info and uses the console.

Function Signatures

error(msg: string | object): void
warn(msg: string | object): void
info(msg: string | object): void
debug(msg: string | object): void
setLogLevel(level: string | number): void
logExpression(msg: string | object, level: string | number)

Where msg is the message to log and then level is a specific log level to use (see below).

Log Levels

The setLogLevel and logExpression functions both allow passing in a string or number to them. Strings should be equal to one of the following available levels:

error
warn
info
debug

Each of these strings can also be used as the function name on the logger object:

logger.error(msg);
logger.warn(msg);
logger.info(msg);
logger.verbose(msg);
logger.debug(msg);
logger.silly(msg);

If you use a number, these correspond to the following levels (being backwards compatible with @cel/logger):

const levels = {
  0: error,
  1: warn,
  2: info,
  3: debug
}

Usage no npm install needed!