lalog

lalog

Logging aggregation and distribution

Installation

npm i lalog --save

Usage

Setup

If logging to Loggly then your Loggly token needs to be set in the LOGGLY_TOKEN environment variable.

If you want to specify a different initial logging level for your application than the default error levels you can set the LALOG_LEVEL environment variable.

Create a Logger

Require the Logger class:

const Logger = require('lalog');

Set the logging level

Logger.setLevel('info');

There are 6 levels:

trace, info, warn, error, fatal, security

If you do not call setLevel(...) then it will default to error and above.

setLevel can be used to change the log level at anytime while your app is running and it will immediately change the level for any loggers that have been created.

Create a logger

const logger = Logger.create({
  serviceName: 'service-name',
  moduleName: 'module-name',
  presets: {}, // optional
  addTrackId: true, // options
});

or

const logger = new Logger({
  serviceName: 'service-name',
  moduleName: 'module-name',
  presets: {}, // optional
  addTrackId: true, // options
});

Notes on create:

• lalog uses debug as one of its destinations. The serviceName and moduleName props allow you to filter debug messages. A debug name of the form serviceName:moduleName will be created which can be used for debugging.
• presets is an optional object that will have its contents merged with any object that's logged. Useful for putting in data that you want logged with every message.
• If addTrackId is truthy then a trackId (uuid) will be added to presets.
• The moduleName is added to presets as module.

Write Log Messages

logger.trace({
  message: 'I am a message'
});

There are 6 levels at which to write log messages:

trace, info, warn, error, fatal, security

The log will only be written to the destination if the log level has be set at this or above. It defaults to error if not set.

The only parameter you can pass to logger.<level>() is an object which will be written to the destination after some modifications have been made to it:

• If the log is error or above then the object will be written to the destination.

time(label) and timeEnd(label, [logObject])

time() and timeEnd() work pretty much the same as console.time() and console.timeEnd().

time('label') starts the timer and timeEnd('label') stops the timer and writes the log.

timeEnd() operates at the info level. i.e. it will only write to the destination if the level is set to info or trace.

timeEnd has the same modifiers that a created logger has inasmuch as it can be called as:

time('label');
// do some stuff
timeEnd.warn('label');
// or
timeEnd.error('label');

timeEnd() and timeEnd.<level>() take an optional log object.

This allows you to do:

try {
  logger.time('write-to-db');
  await writeToDb();
  logger.timeEnd('write-to-db');
} catch(err) {
  logger.timeEnd.error('write-to-db', { err });
}

This saves you from having to do a logger.error() and a logger.timeEnd() if an error is caught. Also if the level is set to error then the timing will be captured in the event of an error (in addition to any extra logging data) but not in the event of normal operation because the default level for logger.timeEnd() is info.

Changelog

0.4.0

• Use LALOG_LEVEL environment variable as the initial log level if it is set and is valid.