Logging

Stellar makes use of the fantastic Winston package for log management. With Winston it is possible to customize log output according to the needs of your project.

Providers

In your config/logger.js file you can customize which transports you would like logger to use. If none are provided, a default logger which only will print to stdout will be used. See Winston’s documentation for a list of all logger types; these include console, file, S3, Riak, and more.

'use strict'

exports.logger = {
  transports: [
    api => {
      return new (winston.transports.Console)({
        colorize: true,
        level: 'debug',
      })
    },

    api => {
      return new (winston.transports.File)({
        filename: `./log/${api.pids.title}.log`,
        level: 'info',
        timestamp: true,
      })
    }
  ]
}

Levels

There are 8 levels of logging; each transport can have a different level. The levels are:

• 0 = debug
• 1 = info
• 2 = notice
• 3 = warning
• 4 = error
• 5 = crit
• 6 = alert
• 7 = emerg

Note: you can customize the levels and colors in the config/logger.js file.

For example, if the log level is set to notice, critical messages are visible, but informational and debug messages are not.

// will use the default 'info' level
api.log('hello!')

// will not show up unless you have configured your logger to be debug
api.log('debug message', 'debug')

// will show up in all logger levels
api.log('Bad things happened :(', 'emerg')

// you can log objects too
api.log('the params were', 'info', action.params)

Methods

The api.logger.log and api.logger[severity] methods are accessible via the api object and allow you to modify the Winston instance directly. The api.log method passes the message to all transports. Below are some examples of using the api.log(message, severity, metadata) method:

// the most basic use - will assume 'info' as the severity
api.log('hello')

// custom severity
api.log('Hmm...', 'warning')

// custom severity with a metadata object
api.log('Red Alert xD', 'emerg', { error: new Error('Some additional information!') })