The exported pino
function takes two optional arguments,
options
and destination
, and
returns a logger instance.
Default: undefined
The name of the logger. When set adds a name
field to every JSON line logged.
Default: 'info'
The minimum level to log: Pino will not log messages with a lower level. Setting this option reduces the load, as typically, debug and trace logs are only valid for development, and not needed in production.
One of 'fatal'
, 'error'
, 'warn'
, 'info
', 'debug'
, 'trace'
or 'silent'
.
Additional levels can be added to the instance via the customLevels
option.
Default: undefined
Use this option to define additional logging levels. The keys of the object correspond to the namespace of the log level, and the values should be the numerical value of the level.
const logger = pino({
customLevels: {
foo: 35
}
})
logger.foo('hi')
Default: false
Use this option to only use defined customLevels
and omit Pino's levels.
Logger's default level
must be changed to a value in customLevels
to use useOnlyCustomLevels
Warning: this option may not be supported by downstream transports.
const logger = pino({
customLevels: {
foo: 35
},
useOnlyCustomLevels: true,
level: 'foo'
})
logger.foo('hi')
logger.info('hello') // Will throw an error saying info is not found in logger object
Default: 5
Option to limit stringification at a specific nesting depth when logging circular objects.
Default: 100
Option to limit stringification of properties/elements when logging a specific object/array with circular references.
Default: undefined
If provided, the mixin
function is called each time one of the active
logging methods is called. The first parameter is the value mergeObject
or an empty object. The second parameter is the log level number.
The function must synchronously return an object. The properties of the returned object will be added to the
logged JSON.
let n = 0
const logger = pino({
mixin () {
return { line: ++n }
}
})
logger.info('hello')
// {"level":30,"time":1573664685466,"pid":78742,"hostname":"x","line":1,"msg":"hello"}
logger.info('world')
// {"level":30,"time":1573664685469,"pid":78742,"hostname":"x","line":2,"msg":"world"}
The result of mixin()
is supposed to be a new object. For performance reason, the object returned by mixin()
will be mutated by pino.
In the following example, passing mergingObject
argument to the first info
call will mutate the global mixin
object by default:
(* See mixinMergeStrategy
option):
const mixin = {
appName: 'My app'
}
const logger = pino({
mixin() {
return mixin;
}
})
logger.info({
description: 'Ok'
}, 'Message 1')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","appName":"My app","description":"Ok","msg":"Message 1"}
logger.info('Message 2')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","appName":"My app","description":"Ok","msg":"Message 2"}
// Note: the second log contains "description":"Ok" text, even if it was not provided.
The mixin
method can be used to add the level label to each log message such as in the following example:
const logger = pino({
mixin(_context, level) {
return { 'level-label': logger.levels.labels[level] }
}
})
logger.info({
description: 'Ok'
}, 'Message 1')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","description":"Ok","level-label":"info","msg":"Message 1"}
logger.error('Message 2')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","level-label":"error","msg":"Message 2"}
If the mixin
feature is being used merely to add static metadata to each log message,
then a child logger β should be used instead.
As of pino 7.x, when the mixin
is used with the nestedKey
option,
the object returned from the mixin
method will also be nested. Prior versions would mix
this object into the root.
const logger = pino({
nestedKey: 'payload',
mixin() {
return { requestId: requestId.currentId() }
}
})
logger.info({
description: 'Ok'
}, 'Message 1')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","payload":{"requestId":"dfe9a9014b","description":"Ok"},"msg":"Message 1"}
Default: undefined
If provided, the mixinMergeStrategy
function is called each time one of the active
logging methods is called. The first parameter is the value mergeObject
or an empty object,
the second parameter is the value resulting from mixin()
(* See mixin
option or an empty object.
The function must synchronously return an object.
// Default strategy, `mergeObject` has priority
const logger = pino({
mixin() {
return { tag: 'docker' }
},
// mixinMergeStrategy(mergeObject, mixinObject) {
// return Object.assign(mixinMeta, mergeObject)
// }
})
logger.info({
tag: 'local'
}, 'Message')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","tag":"local","msg":"Message"}
// Custom mutable strategy, `mixin` has priority
const logger = pino({
mixin() {
return { tag: 'k8s' }
},
mixinMergeStrategy(mergeObject, mixinObject) {
return Object.assign(mergeObject, mixinObject)
}
})
logger.info({
tag: 'local'
}, 'Message')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","tag":"k8s","msg":"Message"}
// Custom immutable strategy, `mixin` has priority
const logger = pino({
mixin() {
return { tag: 'k8s' }
},
mixinMergeStrategy(mergeObject, mixinObject) {
return Object.assign({}, mergeObject, mixinObject)
}
})
logger.info({
tag: 'local'
}, 'Message')
// {"level":30,"time":1591195061437,"pid":16012,"hostname":"x","tag":"k8s","msg":"Message"}
Default: undefined
As an array, the redact
option specifies paths that should
have their values redacted from any log output.
Each path must be a string using a syntax that corresponds to JavaScript dot and bracket notation.
If an object is supplied, three options can be specified:
paths
(array): Required. An array of paths. See redaction - Path Syntax β for specifics.censor
(String|Function|Undefined): Optional. When supplied as a String thecensor
option will overwrite keys that are to be redacted. When set toundefined
the key will be removed entirely from the object. Thecensor
option may also be a mapping function. The (synchronous) mapping function has the signature(value, path) => redactedValue
and is called with the unredactedvalue
andpath
to the key being redacted, as an array. For example given a redaction path ofa.b.c
thepath
argument would be['a', 'b', 'c']
. The value returned from the mapping function becomes the applied censor value. Default:'[Redacted]'
value synchronously. Default:'[Redacted]'
remove
(Boolean): Optional. Instead of censoring the value, remove both the key and the value. Default:false
WARNING: Never allow user input to define redacted paths.
- See the redaction β documentation.
- See fast-redact#caveat β
An object mapping to hook functions. Hook functions allow for customizing internal logger operations. Hook functions must be synchronous functions.
Allows for manipulating the parameters passed to logger methods. The signature
for this hook is logMethod (args, method, level) {}
, where args
is an array
of the arguments that were passed to the log method and method
is the log
method itself, level
is the log level itself. This hook must invoke the
method
function by using apply, like so: method.apply(this, newArgumentsArray)
.
For example, Pino expects a binding object to be the first parameter with an optional string message as the second parameter. Using this hook the parameters can be flipped:
const hooks = {
logMethod (inputArgs, method, level) {
if (inputArgs.length >= 2) {
const arg1 = inputArgs.shift()
const arg2 = inputArgs.shift()
return method.apply(this, [arg2, arg1, ...inputArgs])
}
return method.apply(this, inputArgs)
}
}
An object containing functions for formatting the shape of the log lines. These functions should return a JSONifiable object and should never throw. These functions allow for full customization of the resulting log lines. For example, they can be used to change the level key name or to enrich the default metadata.
Changes the shape of the log level. The default shape is { level: number }
.
The function takes two arguments, the label of the level (e.g. 'info'
)
and the numeric value (e.g. 30
).
ps: The log level cannot be customized when using multiple transports
const formatters = {
level (label, number) {
return { level: number }
}
}
Changes the shape of the bindings. The default shape is { pid, hostname }
.
The function takes a single argument, the bindings object. It will
be called every time a child logger is created.
const formatters = {
bindings (bindings) {
return { pid: bindings.pid, hostname: bindings.hostname }
}
}
Changes the shape of the log object. This function will be called every time
one of the log methods (such as .info
) is called. All arguments passed to the
log method, except the message, will be passed to this function. By default, it does
not change the shape of the log object.
const formatters = {
log (object) {
return object
}
}
Default: {err: pino.stdSerializers.err}
An object containing functions for custom serialization of objects. These functions should return an JSONifiable object and they should never throw. When logging an object, each top-level property matching the exact key of a serializer will be serialized using the defined serializer.
The serializers are applied when a property in the logged object matches a property
in the serializers. The only exception is the err
serializer as it is also applied in case
the object is an instance of Error
, e.g. logger.info(new Error('kaboom'))
.
See errorKey
option to change err
namespace.
Default: undefined
The msgPrefix
property allows you to specify a prefix for every message of the logger and its children.
const logger = pino({
msgPrefix: '[HTTP] '
})
logger.info('got new request!')
// > [HTTP] got new request!
const child = logger.child({})
child.info('User authenticated!')
// > [HTTP] User authenticated!
Default: {pid: process.pid, hostname: os.hostname}
Key-value object added as child logger to each log line.
Set to undefined
to avoid adding pid
, hostname
properties to each log.
Default: true
Set to false
to disable logging.
Default: false
Set to true
to logs newline delimited JSON with \r\n
instead of \n
.
Default: true
Enables or disables the inclusion of a timestamp in the
log message. If a function is supplied, it must synchronously return a partial JSON string
representation of the time, e.g. ,"time":1493426328206
(which is the default).
If set to false
, no timestamp will be included in the output.
See stdTimeFunctions for a set of available functions for passing in as a value for this option.
Example:
timestamp: () => `,"time":"${new Date(Date.now()).toISOString()}"`
// which is equivalent to:
// timestamp: stdTimeFunctions.isoTime
Caution: attempting to format time in-process will significantly impact logging performance.
Default: 'msg'
The string key for the 'message' in the JSON object.
Default: 'err'
The string key for the 'error' in the JSON object.
Default: null
If there's a chance that objects being logged have properties that conflict with those from pino itself (level
, timestamp
, pid
, etc)
and duplicate keys in your log records are undesirable, pino can be configured with a nestedKey
option that causes any object
s that are logged
to be placed under a key whose name is the value of nestedKey
.
This way, when searching something like Kibana for values, one can consistently search under the configured nestedKey
value instead of the root log record keys.
For example,
const logger = require('pino')({
nestedKey: 'payload'
})
const thing = { level: 'hi', time: 'never', foo: 'bar'} // has pino-conflicting properties!
logger.info(thing)
// logs the following:
// {"level":30,"time":1578357790020,"pid":91736,"hostname":"x","payload":{"level":"hi","time":"never","foo":"bar"}}
In this way, logged objects' properties don't conflict with pino's standard logging properties, and searching for logged objects can start from a consistent path.
Browser only, may have asObject
and write
keys. This option is separately
documented in the Browser API β documentation.
- See Browser API β
The transport
option is a shorthand for the pino.transport() function.
It supports the same input options:
require('pino')({
transport: {
target: '/absolute/path/to/my-transport.mjs'
}
})
// or multiple transports
require('pino')({
transport: {
targets: [
{ target: '/absolute/path/to/my-transport.mjs', level: 'error' },
{ target: 'some-file-transport', options: { destination: '/dev/null' }
]
}
})
If the transport option is supplied to pino
, a destination
parameter may not also be passed as a separate argument to pino
:
pino({ transport: {}}, '/path/to/somewhere') // THIS WILL NOT WORK, DO NOT DO THIS
pino({ transport: {}}, process.stderr) // THIS WILL NOT WORK, DO NOT DO THIS
when using the transport
option. In this case, an Error
will be thrown.
- See pino.transport()
The onChild
function is a synchronous callback that will be called on each creation of a new child, passing the child instance as its first argument.
Any error thrown inside the callback will be uncaught and should be handled inside the callback.
const parent = require('pino')({ onChild: (instance) => {
// Execute call back code for each newly created child.
}})
// `onChild` will now be executed with the new child.
parent.child(bindings)
Default: pino.destination(1)
(STDOUT)
The destination
parameter, at a minimum must be an object with a write
method.
An ordinary Node.js stream
can be passed as the destination (such as the result
of fs.createWriteStream
) but for peak log writing performance it is strongly
recommended to use pino.destination
to create the destination stream.
Note that the destination
parameter can be the result of pino.transport()
.
// pino.destination(1) by default
const stdoutLogger = require('pino')()
// destination param may be in first position when no options:
const fileLogger = require('pino')( pino.destination('/log/path'))
// use the stderr file handle to log to stderr:
const opts = {name: 'my-logger'}
const stderrLogger = require('pino')(opts, pino.destination(2))
// automatic wrapping in pino.destination
const fileLogger = require('pino')('/log/path')
// Asynchronous logging
const fileLogger = pino(pino.destination({ dest: '/log/path', sync: false }))
However, there are some special instances where pino.destination
is not used as the default:
- When something, e.g a process manager, has monkey-patched
process.stdout.write
.
In these cases process.stdout
is used instead.
Note: If the parameter is a string integer, e.g. '1'
, it will be coerced to
a number and used as a file descriptor. If this is not desired, provide a full
path, e.g. /tmp/1
.
- See
pino.destination
Default: false
Using the global symbol Symbol.for('pino.metadata')
as a key on the destination
parameter and
setting the key to true
, indicates that the following properties should be
set on the destination
object after each log line is written:
- the last logging level as
destination.lastLevel
- the last logging message as
destination.lastMsg
- the last logging object as
destination.lastObj
- the last time as
destination.lastTime
, which will be the partial string returned by the time function. - the last logger instance as
destination.lastLogger
(to support child loggers)
The following is a succinct usage example:
const dest = pino.destination('/dev/null')
dest[Symbol.for('pino.metadata')] = true
const logger = pino(dest)
logger.info({a: 1}, 'hi')
const { lastMsg, lastLevel, lastObj, lastTime} = dest
console.log(
'Logged message "%s" at level %d with object %o at time %s',
lastMsg, lastLevel, lastObj, lastTime
) // Logged message "hi" at level 30 with object { a: 1 } at time 1531590545089
The logger instance is the object returned by the main exported
pino
function.
The primary purpose of the logger instance is to provide logging methods.
The default logging methods are trace
, debug
, info
, warn
, error
, and fatal
.
Each logging method has the following signature:
([mergingObject], [message], [...interpolationValues])
.
The parameters are explained below using the logger.info
method but the same applies to all logging methods.
An object can optionally be supplied as the first parameter. Each enumerable key and value
of the mergingObject
is copied into the JSON log line.
logger.info({MIX: {IN: true}})
// {"level":30,"time":1531254555820,"pid":55956,"hostname":"x","MIX":{"IN":true}}
If the object is of type Error, it is wrapped in an object containing a property err ({ err: mergingObject }
).
This allows for a unified error handling flow.
Options serializers
and errorKey
could be used at instantiation time to change the namespace
from err
to another string as preferred.
A message
string can optionally be supplied as the first parameter, or
as the second parameter after supplying a mergingObject
.
By default, the contents of the message
parameter will be merged into the
JSON log line under the msg
key:
logger.info('hello world')
// {"level":30,"time":1531257112193,"msg":"hello world","pid":55956,"hostname":"x"}
The message
parameter takes precedence over the mergingObject
.
That is, if a mergingObject
contains a msg
property, and a message
parameter
is supplied in addition, the msg
property in the output log will be the value of
the message
parameter not the value of the msg
property on the mergingObject
.
See Avoid Message Conflict for information
on how to overcome this limitation.
If no message
parameter is provided, and the mergingObject
is of type Error
or it has a property named err
, the
message
parameter is set to the message
value of the error. See option errorKey
if you want to change the namespace.
The messageKey
option can be used at instantiation time to change the namespace
from msg
to another string as preferred.
The message
string may contain a printf style string with support for
the following placeholders:
%s
β string placeholder%d
β digit placeholder%O
,%o
, and%j
β object placeholder
Values supplied as additional arguments to the logger method will then be interpolated accordingly.
All arguments supplied after message
are serialized and interpolated according
to any supplied printf-style placeholders (%s
, %d
, %o
|%O
|%j
) to form
the final output msg
value for the JSON log line.
logger.info('%o hello %s', {worldly: 1}, 'world')
// {"level":30,"time":1531257826880,"msg":"{\"worldly\":1} hello world","pid":55956,"hostname":"x"}
Since pino v6, we do not automatically concatenate and cast to string consecutive parameters:
logger.info('hello', 'world')
// {"level":30,"time":1531257618044,"msg":"hello","pid":55956,"hostname":"x"}
// world is missing
However, it's possible to inject a hook to modify this behavior:
const pinoOptions = {
hooks: { logMethod }
}
function logMethod (args, method) {
if (args.length === 2) {
args[0] = `${args[0]} %j`
}
method.apply(this, args)
}
const logger = pino(pinoOptions)
Errors can be supplied as either the first parameter or if already using mergingObject
then as the err
property on the mergingObject
.
Options serializers
and errorKey
could be used at instantiation time to change the namespace
from err
to another string as preferred.
This section describes the default configuration. The error serializer can be mapped to a different key using the
serializers
option.
logger.info(new Error("test"))
// {"level":30,"time":1531257618044,"msg":"test","stack":"...","type":"Error","pid":55956,"hostname":"x"}
logger.info({ err: new Error("test"), otherkey: 123 }, "some text")
// {"level":30,"time":1531257618044,"err":{"msg": "test", "stack":"...","type":"Error"},"msg":"some text","pid":55956,"hostname":"x","otherkey":123}
Write a 'trace'
level log, if the configured level
allows for it.
- See
mergingObject
log method parameter - See
message
log method parameter - See
...interpolationValues
log method parameter
Write a 'debug'
level log, if the configured level
allows for it.
- See
mergingObject
log method parameter - See
message
log method parameter - See
...interpolationValues
log method parameter
Write an 'info'
level log, if the configured level
allows for it.
- See
mergingObject
log method parameter - See
message
log method parameter - See
...interpolationValues
log method parameter
Write a 'warn'
level log, if the configured level
allows for it.
- See
mergingObject
log method parameter - See
message
log method parameter - See
...interpolationValues
log method parameter
Write a 'error'
level log, if the configured level
allows for it.
- See
mergingObject
log method parameter - See
message
log method parameter - See
...interpolationValues
log method parameter
Write a 'fatal'
level log, if the configured level
allows for it.
Since 'fatal'
level messages are intended to be logged just before the process exiting the fatal
method will always sync flush the destination.
Therefore it's important not to misuse fatal
since
it will cause performance overhead if used for any
other purpose than writing final log messages before
the process crashes or exits.
- See
mergingObject
log method parameter - See
message
log method parameter - See
...interpolationValues
log method parameter
Noop function.
The logger.child
method allows for the creation of stateful loggers,
where key-value pairs can be pinned to a logger causing them to be output
on every log line.
Child loggers use the same output stream as the parent and inherit the current log level of the parent at the time they are spawned.
The log level of a child is mutable. It can be set independently
of the parent either by setting the level
accessor after creating
the child logger or using the options.level
key.
An object of key-value pairs to include in every log line output via the returned child logger.
const child = logger.child({ MIX: {IN: 'always'} })
child.info('hello')
// {"level":30,"time":1531258616689,"msg":"hello","pid":64849,"hostname":"x","MIX":{"IN":"always"}}
child.info('child!')
// {"level":30,"time":1531258617401,"msg":"child!","pid":64849,"hostname":"x","MIX":{"IN":"always"}}
The bindings
object may contain any key except for reserved configuration keys level
and serializers
.
Use options.serializers
instead.
Options for child logger. These options will override the parent logger options.
The level
property overrides the log level of the child logger.
By default, the parent log level is inherited.
After the creation of the child logger, it is also accessible using the logger.level
key.
const logger = pino()
logger.debug('nope') // will not log, since default level is info
const child = logger.child({foo: 'bar'}, {level: 'debug'})
child.debug('debug!') // will log as the `level` property set the level to debug
Default: undefined
The msgPrefix
property allows you to specify a prefix for every message of the child logger.
By default, the parent prefix is inherited.
If the parent already has a prefix, the prefix of the parent and then the child will be displayed.
const logger = pino({
msgPrefix: '[HTTP] '
})
logger.info('got new request!')
// > [HTTP] got new request!
const child = logger.child({avengers: 'assemble'}, {msgPrefix: '[Proxy] '})
child.info('message proxied!')
// > [HTTP] [Proxy] message proxied!
Setting options.redact
to an array or object will override the parent redact
options. To remove redact
options inherited from the parent logger set this value as an empty array ([]
).
const logger = require('pino')({ redact: ['hello'] })
logger.info({ hello: 'world' })
// {"level":30,"time":1625794363403,"pid":67930,"hostname":"x","hello":"[Redacted]"}
const child = logger.child({ foo: 'bar' }, { redact: ['foo'] })
logger.info({ hello: 'world' })
// {"level":30,"time":1625794553558,"pid":67930,"hostname":"x","hello":"world", "foo": "[Redacted]" }
- See
redact
option
Child loggers inherit the serializers from the parent logger.
Setting the serializers
key of the options
object will override
any configured parent serializers.
const logger = require('pino')()
logger.info({test: 'will appear'})
// {"level":30,"time":1531259759482,"pid":67930,"hostname":"x","test":"will appear"}
const child = logger.child({}, {serializers: {test: () => `child-only serializer`}})
child.info({test: 'will be overwritten'})
// {"level":30,"time":1531259784008,"pid":67930,"hostname":"x","test":"child-only serializer"}
Returns an object containing all the current bindings, cloned from the ones passed in via logger.child()
.
const child = logger.child({ foo: 'bar' })
console.log(child.bindings())
// { foo: 'bar' }
const anotherChild = child.child({ MIX: { IN: 'always' } })
console.log(anotherChild.bindings())
// { foo: 'bar', MIX: { IN: 'always' } }
Flushes the content of the buffer when using pino.destination({ sync: false })
.
This is an asynchronous, fire and forget, operation.
The use case is primarily for asynchronous logging, which may buffer
log lines while others are being written. The logger.flush
method can be
used to flush the logs
on a long interval, say ten seconds. Such a strategy can provide an
optimum balance between extremely efficient logging at high demand periods
and safer logging at low demand periods.
Set this property to the desired logging level.
The core levels and their values are as follows:
Level: | trace | debug | info | warn | error | fatal | silent |
Value: | 10 | 20 | 30 | 40 | 50 | 60 | Infinity |
The logging level is a minimum level based on the associated value of that level.
For instance if logger.level
is info
(30) then info
(30), warn
(40), error
(50), and fatal
(60) log methods will be enabled but the trace
(10) and debug
(20) methods, being less than 30, will not.
The silent
logging level is a specialized level that will disable all logging,
the silent
log method is a noop function.
A utility method for determining if a given log level will write to the destination.
The given level to check against:
if (logger.isLevelEnabled('debug')) logger.debug('conditional log')
Defines the method name of the new level.
- See
logger.level
Defines the associated minimum threshold value for the level, and therefore where it sits in order of priority among other levels.
- See
logger.level
Supplies the integer value for the current logging level.
if (logger.levelVal === 30) {
console.log('logger level is `info`')
}
Levels are mapped to values to determine the minimum threshold that a
logging method should be enabled at (see logger.level
).
The logger.levels
property holds the mappings between levels and values,
and vice versa.
$ node -p "require('pino')().levels"
{ labels:
{ '10': 'trace',
'20': 'debug',
'30': 'info',
'40': 'warn',
'50': 'error',
'60': 'fatal' },
values:
{ fatal: 60, error: 50, warn: 40, info: 30, debug: 20, trace: 10 } }
- See
logger.level
Returns the serializers as applied to the current logger instance. If a child logger did not register its own serializer upon instantiation the serializers of the parent will be returned.
The logger instance is also an EventEmitter β
A listener function can be attached to a logger via the level-change
event
The listener is passed five arguments:
levelLabel
β the new level string, e.gtrace
levelValue
βΒ the new level number, e.g10
previousLevelLabel
β the prior level string, e.ginfo
previousLevelValue
β the prior level number, e.g30
logger
β the logger instance from which the event originated
const logger = require('pino')()
logger.on('level-change', (lvl, val, prevLvl, prevVal) => {
console.log('%s (%d) was changed to %s (%d)', prevLvl, prevVal, lvl, val)
})
logger.level = 'trace' // trigger event
Please note that due to a known bug, every logger.child()
call will
fire a level-change
event. These events can be ignored by writing an event handler like:
const logger = require('pino')()
logger.on('level-change', function (lvl, val, prevLvl, prevVal, instance) {
if (logger !== instance) {
return
}
console.log('%s (%d) was changed to %s (%d)', prevLvl, prevVal, lvl, val)
})
logger.child({}); // trigger an event by creating a child instance, notice no console.log
logger.level = 'trace' // trigger event using actual value change, notice console.log
Exposes the Pino package version. Also available on the exported pino
function.
- See
pino.version
Create a Pino Destination instance: a stream-like object with significantly more throughput than a standard Node.js stream.
const pino = require('pino')
const logger = pino(pino.destination('./my-file'))
const logger2 = pino(pino.destination())
const logger3 = pino(pino.destination({
dest: './my-file',
minLength: 4096, // Buffer before writing
sync: false // Asynchronous logging, the default
}))
const logger4 = pino(pino.destination({
dest: './my-file2',
sync: true // Synchronous logging
}))
The pino.destination
method may be passed a file path or a numerical file descriptor.
By default, pino.destination
will use process.stdout.fd
(1) as the file descriptor.
pino.destination
is implemented on sonic-boom
β.
A pino.destination
instance can also be used to reopen closed files
(for example, for some log rotation scenarios), see Reopening log files.
Create a stream that routes logs to a worker thread that wraps around a Pino Transport.
const pino = require('pino')
const transport = pino.transport({
target: 'some-transport',
options: { some: 'options for', the: 'transport' }
})
pino(transport)
Multiple transports may also be defined, and specific levels can be logged to each transport:
const pino = require('pino')
const transport = pino.transport({
targets: [{
level: 'info',
target: 'pino-pretty' // must be installed separately
}, {
level: 'trace',
target: 'pino/file',
options: { destination: '/path/to/store/logs' }
}]
})
pino(transport)
A pipeline could also be created to transform log lines before sending them:
const pino = require('pino')
const transport = pino.transport({
pipeline: [{
target: 'pino-syslog' // must be installed separately
}, {
target: 'pino-socket' // must be installed separately
}]
})
pino(transport)
If WeakRef
, WeakMap
, and FinalizationRegistry
are available in the current runtime (v14.5.0+), then the thread
will be automatically terminated in case the stream or logger goes out of scope.
The transport()
function adds a listener to process.on('beforeExit')
and process.on('exit')
to ensure the worker
is flushed and all data synced before the process exits.
Note that calling process.exit()
on the main thread will stop the event loop on the main thread from turning. As a result,
using console.log
and process.stdout
after the main thread called process.exit()
will not produce any output.
If you are embedding/integrating pino within your framework, you will need to make pino aware of the script that is calling it, like so:
const pino = require('pino')
const getCaller = require('get-caller-file')
module.exports = function build () {
const logger = pino({
transport: {
caller: getCaller(),
target: 'transport',
options: { destination: './destination' }
}
})
return logger
}
For more on transports, how they work, and how to create them see the Transports documentation
.
- See
Transports
- See
thread-stream
β
target
: The transport to pass logs through. This may be an installed module name or an absolute path.options
: An options object which is serialized (see [Structured Clone Algorithm][https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm]), passed to the worker thread, parsed and then passed to the exported transport function.worker
: Worker thread configuration options. Additionally, theworker
option supportsworker.autoEnd
. If this is set tofalse
logs will not be flushed on process exit. It is then up to the developer to calltransport.end()
to flush logs.targets
: May be specified instead oftarget
. Must be an array of transport configurations. Transport configurations include the aforementionedoptions
andtarget
options plus alevel
option which will send only logs above a specified level to a transport.pipeline
: May be specified instead oftarget
. Must be an array of transport configurations. Transport configurations include the aforementionedoptions
andtarget
options. All intermediate steps in the pipeline must beTransform
streams and notWritable
.dedupe
: See pino.multistream options
Create a stream composed by multiple destination streams and returns an object implementing the MultiStreamRes interface.
var fs = require('fs')
var pino = require('pino')
var pretty = require('pino-pretty')
var streams = [
{stream: fs.createWriteStream('/tmp/info.stream.out')},
{stream: pretty() },
{level: 'debug', stream: fs.createWriteStream('/tmp/debug.stream.out')},
{level: 'fatal', stream: fs.createWriteStream('/tmp/fatal.stream.out')}
]
var log = pino({
level: 'debug' // this MUST be set at the lowest level of the
// destinations
}, pino.multistream(streams))
log.debug('this will be written to /tmp/debug.stream.out')
log.info('this will be written to /tmp/debug.stream.out and /tmp/info.stream.out')
log.fatal('this will be written to /tmp/debug.stream.out, /tmp/info.stream.out and /tmp/fatal.stream.out')
In order for multistream
to work, the log level must be set to the lowest level used in the streams array. Default is info
.
levels
: Pass custom log level definitions to the instance as an object.
-
dedupe
: Set this totrue
to send logs only to the stream with the higher level. Default:false
dedupe
flag can be useful for example when usingpino.multistream
to redirecterror
logs toprocess.stderr
and others toprocess.stdout
:var pino = require('pino') var multistream = pino.multistream var streams = [ {level: 'debug', stream: process.stdout}, {level: 'error', stream: process.stderr}, ] var opts = { levels: { silent: Infinity, fatal: 60, error: 50, warn: 50, info: 30, debug: 20, trace: 10 }, dedupe: true, } var log = pino({ level: 'debug' // this MUST be set at the lowest level of the // destinations }, multistream(streams, opts)) log.debug('this will be written ONLY to process.stdout') log.info('this will be written ONLY to process.stdout') log.error('this will be written ONLY to process.stderr') log.fatal('this will be written ONLY to process.stderr')
The pino.stdSerializers
object provides functions for serializing objects common to many projects. The standard serializers are directly imported from pino-std-serializers.
The timestamp
option can accept a function that determines the
timestamp
value in a log line.
The pino.stdTimeFunctions
object provides a very small set of common functions for generating the
timestamp
property. These consist of the following
-
pino.stdTimeFunctions.epochTime
: Milliseconds since Unix epoch (Default) -
pino.stdTimeFunctions.unixTime
: Seconds since Unix epoch -
pino.stdTimeFunctions.nullTime
: Clears timestamp property (Used whentimestamp: false
) -
pino.stdTimeFunctions.isoTime
: ISO 8601-formatted time in UTC -
See
timestamp
option
For integration purposes with ecosystem and third-party libraries pino.symbols
exposes the symbols used to hold non-public state and methods on the logger instance.
Access to the symbols allows logger state to be adjusted, and methods to be overridden or proxied for performant integration where necessary.
The pino.symbols
object is intended for library implementers and shouldn't be utilized
for general use.
Exposes the Pino package version. Also available on the logger instance.
- See
logger.version
Properties:
write(data)
data
Object | string- Returns: void
Write data
onto the streams held by the current instance.
add(dest)
dest
StreamEntry | DestinationStream- Returns: MultiStreamRes
Add dest
stream to the array of streams of the current instance.
flushSync()
- Returns:
undefined
- Returns:
Call flushSync
on each stream held by the current instance.
minLevel
- number
The minimum level amongst all the streams held by the current instance.
streams
- Returns: StreamEntry[]
The array of streams currently held by the current instance.
clone(level)
level
Level- Returns: MultiStreamRes
Returns a cloned object of the current instance but with the provided level
.
Properties:
stream
- DestinationStream
level
- Optional: Level
Properties:
write(msg)
msg
string
- Values:
"fatal"
|"error"
|"warn"
|"info"
|"debug"
|"trace"