Logging

Hemera use Pino an extremely fast node.js json logger, inspired by Bunyan. It also includes a shell utility to pretty-print its log files.

Logging

hemera.log.info('fooBar')
hemera.log.error('fooBar')

hemera.act(
  {
    topic: 'a',
    cmd: 'a'
  },
  function(err, resp) {
    this.log.error(err)
  }
)

Pretty logs

Pretty logging is disabled by default but you can enable it with prettyLog option. Before you can use it you have install the pino-pretty package.

npm install --save-dev pino-pretty

const hemera = new Hemera(nats, {
  logLevel: 'info',
  prettyLog: true
})
// or
const hemera = new Hemera(nats, {
  logLevel: 'info',
  prettyLog: {} // pino-pretty options
})

Attach tracing information to each log

This will add tracing and request informations to each log.

const hemera = new Hemera(nats, {
  logLevel: 'info',
  traceLog: true
})

Configure log level

const hemera = new Hemera(nats, {
  logLevel: 'info'
})

Log levels

• info
• warn
• debug
• trace
• error
• fatal

Child logger

The default logger provide a function to create child loggers. This is used inside Hemera to create a logger context inside plugins.

hemera.log.child({ plugin: 'foo' }).info('test')

Pass custom stream

This is useful for debugging and to implement your own serializer.

const split = require('split2')
const stream = split(JSON.parse)
const hemera = new Hemera(nats, {
  logLevel: 'info',
  logger: stream
})
stream.once('data', line => {
  // some code
})
hemera.log.info('test')

Use you own logger

You can pass your own logger but it must implement all log levels and the child logger function.

const split = require('split2')
const stream = split(JSON.parse)
const hemera = new Hemera(nats, {
  logger: {
    info: function() {},
    child: function() {
      return this
    }
  }
})
hemera.log.info('test')