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