Package Exports

@neo9/n9-node-log
@neo9/n9-node-log/dist/src/index.js

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Readme

n9-node-log

Logging node module based on Pino.

Requirements

NodeJS >= 10.0.0

Installation

npm install --save @neo9/n9-node-log

Usage

import n9Log from '@neo9/n9-node-log';

const log = n9Log('my-app-name');

// Write on stdout
log.trace('This is a trace message');
log.debug('This is a debug message');
log.info('This is an information message');
log.warn('Warning, this feature will be removed soon');
// Write on stderr
log.error('An error appened');

2017-05-12T15:57:14.474Z - info: [my-app-name] This is an information message
2017-05-12T15:57:14.689Z - warn: [my-app-name] Warning, this feature will be removed soon
2017-05-12T15:57:14.974Z - error: [my-app-name] An error appened

Metadata

log.info('Log with metadata', { anything: 'this is metadata' });
log.error('Here an error', new Error('hello'));

2017-05-12T15:57:14.474Z - info: [my-app-name] Log with metadata anything=this is metadata
2017-05-12T15:57:14.785Z - error: [node-ts-skeleton] Here an error Error: hello
     err: {
      "type": "Error",
      "message": "something-went-wrong",
      "stack":
          Error: something-went-wrong
              at /home/bdaniel/projects/neo9/n9-libs/n9-node-log/test/index.ts:110:29
    }

Prefixing

const logUsers = log.module('users');

logUsers.info('Log specific to users module');

2017-05-12T15:57:14.474Z - info: [my-app-name:users] Log specific to users module

Profiling

log.profile('test');
setTimeout(() => log.profile('test'), 1000);

2017-05-12T15:57:14.474Z - info: [my-app-name] test {"durationMs":1000}

Log level

You can filter the list of logs on startup with the N9LOG environment or with the level option.

Possible values:

trace: Display all logs
debug: Display debug + info + warn + error logs
info: Display info + warn + error logs
warn: Display warn + error logs
error: Display only error logs

Default value: info

Example: N9LOG=error node server.js will display only error logs.

For performance matter, you can check if you need to compute your log data :

if (log.isLevelEnabled('debug')) {
    log.debug('My debug log', { complexDataAsOneField: JSON.stringify(data) });
}

Breaking changes from V3 to V4

Log level verbose renamed to log level trace
JSON Format is enabled by default, it wasn't before
Remove transports features
Filters function change their signatures