Winston namespace

This package is a wrapper for the winston logger that has the functionality to create loggers with namespaces, that is that you can log information but with labels, the console will look like:

[verifyClient] 2018-1-17 15:50:08.909 - INFO: Client verified
[websocket] 2018-1-17 15:50:08.925 - INFO: New connection. ID: f23ab1ff-f925-4360-9a93-6f9d11e70f3b
[websocket] 2018-1-17 15:50:14.222 - INFO: Received message from f23ab1ff-f925-4360-9a93-6f9d11e70f3b.
[applogic:api] 2018-1-17 15:50:14.222 - INFO: Sending message to app logic
[messagesDispatcher] 2018-1-17 15:50:14.784 - INFO: Dispatching data to user 'f23ab1ff-f925-4360-9a93-6f9d11e70f3b'

Where in the [ ] is the namespace for clarity. But the power of this wrapper is that you can filter your logs by level (like working only with winston) but also by namespace, so you can debug by module/label/namespace.

Usage

The usage is very similar to winston with the levels but now is more simple to log by modules. Create the logger:

const logger = require('winston-namespace')('namespace')
...
logger.error(new Error('This is an error').stack)
logger.info('This is an info message.')

The logger came with its own formatter to show the namespace and the timestamp, but if you want to pass your own options to winston you can:

const logger = require('winston-namespace')('namespace', {level: 'info'})

Filter

The debug and the silly mode can be disabled by modules. For example if you create a logger with the namespace 'server' and another with the namespace 'app', in the LOG_NAMESPACES environment variable you can write 'server,app' (separated by comma) to log both, only 'server' if you don't want to see debug messages for the 'app' module or only 'app' to see the app's debug messages. It also has wildcards ('*'). For example you can write 'app:api,app:logic,app:controller', or only write 'app:*' that will work for all the cases that are subspaces of 'app'. Or in the case that you want to debug all you can write LOG_NAMESPACES = *. The level of the log is the same as winston and you can set it the in LOG_LEVEL env variable. It could be:

• error
• warn
• info
• debug
• silly

Example of filtering:

const logger1 = require('winston-namespace')('app:api')
const logger2 = require('winston-namespace')('app:controller')
const logger3 = require('winston-namespace')('view')

process.env.LOG_NAMESPACES = 'app:*'
process.env.LOG_LEVEL = 'debug'

logger1.info('Testing info')
// > [app:api] Date&Time - INFO: Testing info
logger2.info('Testing info for controller.')
// > [app:controller] Date&Time - INFO: Testing info for controller.
logger1.silly('This message won\'t be shown.')
logger3.info('This message won\'t be shown too.')