@kofile/log
v4.3.0
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Node log wrapper
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Log
Log is a thin wrapper around a logging engine. It supports
- limiting log output based on log level
- creating high-resolution timers for instrumenting code
- any engine with the appropriate adapater
At present, these adapters are included by default:
console
noop
(does nothing)
Usage
Create a log:
const { makeLog } = require('@kofile/log')
const log = makeLog()
By default, your adapter will be console
and the log level will be set to DEBUG
.
See available log levels with
Log.LEVELS //=> ERROR, WARN, INFO, & DEBUG
You can pass in a different level when you instantiate your log:
const log = makeLog({ level: Log.LEVELS.INFO })
If you want to use another adapter, pass it in to the constructor as well:
const { Adapters } = require('@kofile/log')
const log = makeLog({ adapter: new Adapters.File() })
NOTE The File adapter currently doesn't exist. :wink:
If you want access to export the LEVELS
, you can do so:
const { LEVELS } = require('@kofile/log')
LEVELS.DEBUG //=> 'DEBUG'
You can also pass in a meta
object, which will be rendered with every log message as stringified JSON
:
const meta = { foo: 'bar' }
const log = makeLog({ meta })
log.info('test message')
//=> `1984-10-04T06:12:43.453Z [DEBUG] test message -- {"foo":"bar"}`
Meta must be an object.
You can pass in tags to use to group messages together:
const log = makeLog({ tags: ['api', 'will-fix'] })
log.info('test message')
//=> `1984-10-04T06:12:43.453Z [DEBUG] #api #will-fix test message`
Tags
- may only contain alphanumeric characters and dashes
- may not contain double dashes
--
- can be added with
spawn()
(new tags will be added to old tags)
API
Setting SILENCE_LOG
to any truthy value will setup the logger to use the Noop Adapter.
Log
log.level
Returns the configured log level.
ERROR
will only log messages created withlog.error
WARN
will log messages created withlog.error
andlog.warn
INFO
will log messages created withlog.error
,log.warn
, andlog.info
DEBUG
will log all messages
Use Log.LEVELS
when specifying levels for log initialization.
log.level = newLevel
Set the given level as the new log level for this instance.
Log level must be one of Log.LEVELS
.
log.adapter
Returns the adapter used by this instance of Log
.
log.defaultTimerCallback = cb
Set the given callback function cb
as the default callback function for timers to execute when they complete.
The callback function will receive (message, [durationSeconds, durationNanoseconds])
.
Example:
const { makeLog } = require('@kofile/log')
const statsd = require('./statsd')
const log = makeLog()
const timerCallback = (message, duration) => {
statsd.timing(message, duration)
}
log.defaultTimerCallback = timerCallback
const timer1 = log.makeTimer('timer-1')
const timer1 = log.makeTimer('timer-2')
const timer1 = log.makeTimer('timer-3')
timer1.start()
timer2.start()
timer3.start()
timer1.end() //=> calls timerCallback with details for timer1
timer2.end() //=> calls timerCallback with details for timer2
timer3.end() //=> calls timerCallback with details for timer3
log.error(message[, error[, supplementalInfo]])
Log an error message. Give an actual instance of Error
as the second argument. Provide any additional information (as an object) as supplementalInfo
.
log.warn(message, [...args])
log.info(message, [...args])
log.debug(message, [...args])
log.makeTimer(key, [callback])
Returns a preconfigured instance of Timer
.
If the optional callback is provided, when the timer instance ends, the callback will be invoked.
log.spawn([meta, tags])
Returns a new instance of log
with the same initialization parameters as its parent.
- if a
meta
object is provided, it will be merged in with existingmeta
- if a
tags
array is provided, the new tags will be merged with the old tags
Timer
Please see the Timer documentation.
Supported Platforms
Node 7+
Testing
Run tests with yarn test