Logger

Install

npm install @bitrefill/logger

Usage

const log = require('@bitrefill/logger')('my-module');

log.info('Regular operation');
log.warn('Something is off but not critical');
log.error('Someone should look into this');

log.info('With an object', { my: { deep: 'object' } });
log.info('A number', 100000000);
log.info('Multiple arguments:', 'isProduction', true, 'amount', 27);

log.error(new Error('Oops!'));
log.error('Error with a message', new Error('Oops, I did it again!'));
log.error('Error within an object, error prop', { error: new Error('An error!'), amount: 0.00081 });
log.error('Error within an object, err prop', { err: new Error('An err!'), amount: 0.00081 });
log.error('Error within an object, e prop', { e: new Error('An e!'), amount: 0.00081 });

Will output:

{"level":30,"time":1521079820856,"msg":"Regular operation","namespace":"my-module","v":1}
{"level":40,"time":1521079820858,"msg":"Something is off but not critical","namespace":"my-module","v":1}
{"level":50,"time":1521079820858,"msg":"Someone should look into this","namespace":"my-module","v":1}

{"level":30,"time":1521080308250,"msg":"With an object","namespace":"my-module","my":{"deep":"object"},"v":1}
{"level":30,"time":1521080308250,"msg":"A number 100000000","namespace":"my-module","v":1}
{"level":30,"time":1521080308250,"msg":"Multiple arguments: isProduction true amount 27","namespace":"my-module","v":1}

{"level":50,"time":1521080917001,"msg":"Oops!","namespace":"my-module","type":"Error","stack":"Error: Oops!\n    at Object.
<anonymous>...","v":1}
{"level":50,"time":1521080917001,"msg":"Error with a message","namespace":"my-module","type":"Error","stack":"Error: Oops,
I did it again!\n    at Object.<anonymous>...","v":1}
{"level":50,"time":1521080917001,"msg":"Error within an object, error prop","namespace":"my-module","error":{"type":"Error"
,"message":"An error!","stack":"Error: An error!\n    at Object.<anonymous>..."},"amount":0.00081,"v":1}
{"level":50,"time":1521080917002,"msg":"Error within an object, err prop","namespace":"my-module","err":{"type":"Error","me
ssage":"An err!","stack":"Error: An err!\n    at Object.<anonymous>..."},"amount":0.00081,"v":1}
{"level":50,"time":1521080917002,"msg":"Error within an object, e prop","namespace":"my-module","e":{"type":"Error","messag
e":"An e!","stack":"Error: An e!\n    at Object.<anonymous>..."},"amount":0.00081,"v":1}

Note: For brevity the stack has been shortened but in practice the entire error stack will be logged as a string.

Config

The library is configurable through ENV vars.

APP_NAME

Every log line will output the value of this variable. Use for different app instances. Eg.: api, worker, etc. .

NODE_ENV

If equal to development the logs will be pretty printed for easier debugging on localhost.

[2018-03-15T02:41:38.460Z] INFO: Regular operation
    namespace: "my-module"

Note: NODE_ENV=test will silent all logs

CLI

We provide a command line interface that can be used to parse Heroku live tail into an easy to read format.

To use the command line tool, you can install the module globally:

npm install -g @bitrefill/logger

Then pipe the Heroku live tail output:

heroku logs -t -a my-app | logger

Options

-i, --include

Which JSON properties to include. Specify one or more property names, separated by commas. By default all JSON properties are included.

License

Licensed under the MIT License, Copyright © 2018 Airfill Prepaid AB.

See LICENSE for more information.