@fengcart/logger v1.17.0

@fengcart/logger

New Shared logging library for CTG

Installation

yarn add @fengcart/logger

Usage

The default logger will cover almost all use cases.

import log from '@fengcart/logger';

function hello() {
  log.info({ data: 'Some data' }, 'A log message');
}

Output

2018-12-20T17:05:25.330Z  INFO  A log message
{
   "level": 30,
   "message": "Some A log message",
   "data": "Some data"
}

Lambda Functions

For usage in a Lambda function, you can capture request information which will append the request and tracing IDs to all log statements. This functionality is provided by pino-lamdba.

See the default tags that are tracked in Lambda functions.

The usage of withRequest is global, that is, you do not need to pass instances of logger around to other classes or functions. Calling withRequest once will track tags in ALL logger instances across the application, regardless of the method you use to import or create the logger.

import log from '@fengcart/logger';

export async function handler(event, context) {
  log.withRequest(event, context);

  log.info({ data: 'Some data' }, 'A log message');
}

Output

2018-12-20T17:05:25.330Z    6fccb00e-0479-11e9-af91-d7ab5c8fe19e    INFO  A log message
{
   "awsRequestId": "6fccb00e-0479-11e9-af91-d7ab5c8fe19e",
   "x-correlation-id": "238da608-0542-11e9-8eb2-f2801f1b9fd1",
   "x-correlation-trace-id": "Root=1-5c1bcbd2-9cce3b07143efd5bea1224f2;Parent=07adc05e4e92bf13;Sampled=1",
   "level": 30,
   "message": "Some A log message",
   "data": "Some data"
}

Default Tags

By default, the following tags are tracked in all log messages

These tags are compatible with what Datadog expects and AWS specific metrics will be ignored in non-aws environments.

Configuration

Log level output is controlled by environment variables set to fatal, error, warn, info (default), debug, trace, or silent

LOG_LEVEL=debug

Log level can also be controlled by upstream requests. If an incoming request contains a header of x-correlation-debug set to true, the logger will be set to debug level for that request.

In rare cases where the logger needs to be customized further, we will support all options that the underlying logging provider itself supports for configuration (by default pino).

Local Development

Local development provides a more readable output using pino-pretty by setting the LOG_PRETTY environment variable to true;

Child Loggers

You can create named child loggers which will output to add an additional tags to all messages.

import logger from '@fengcart/logger';

const childLogger = logger.child({
  module: 'Foo',
  // any additional tags
});

childLogger.info({ data: 'Some data' }, 'A log message');

Output

2018-12-20T17:05:25.330Z    6fccb00e-0479-11e9-af91-d7ab5c8fe19e    INFO  A log message
{
   "awsRequestId": "6fccb00e-0479-11e9-af91-d7ab5c8fe19e",
   "x-correlation-id": "238da608-0542-11e9-8eb2-f2801f1b9fd1",
   "x-correlation-trace-id": "Root=1-5c1bcbd2-9cce3b07143efd5bea1224f2;Parent=07adc05e4e92bf13;Sampled=1",
   "level": 30,
   "message": "Some A log message",
   "data": "Some data",
   "module": "Foo"
}

Custom Loggers

// logger.ts
import { create } from '@fengcart/logger';
export default create({
  // any pino options
});

// handler.ts
import log from './logger';

export async function handler(event, context) {
  log.withRequest(event, context);

  log.info({ data: 'Some data' }, 'A log message');
}

NestJS

The ApiLogger class implements a simple NestJS LoggerService that logs with the RBI logger instance.

import { ApiLogger } from '@fengcart/logger';

const app = await NestFactory.create(AppModule, { logger: new ApiLogger() });