Common logging for Node.js Lambdas

This logger library provides an easier way to initialise execution-wide AWS loggers that will share the same metadata object within the lambda execution. We use _X_AMZN_TRACE_ID - automatically generated environment variable to differentiate between executions. AWS Lambdas executions share environment variables except for that one.

That's also allowing us to get logger in any part of our application without need to pass logger object or context. See examples to get more details.

Behind the scenes we use winston logger.

Install

npm i --save @assetchain/logging-nodejs-lambda

Example

Here is the example how to use parameter discovery service in your lambda

// Main js file
import { createLogger } from '@assetchain/logging-nodejs-lambda';
import { otherFunction } from './secondary.js';

export async function handler(event, context, callback) {
  const log = createLogger({ context });

  // Do your mumbo-jumbo
  // ....
  const { memberId, something } = ...;
    
  // Log text
  log.info(`Something is ${something}`);
  
  // Add common metadata using predefined methods
  log.setMember(memberId);
  
  // Log json
  log.info({pew: 123});
  
  // Update meta manually (you shouldn't)
  log.meta().customProperty = 123;
  
  otherFunction();
}

// ./secondary.js
import { getLogger } from '@assetchain/logging-nodejs-lambda';

export otherFunction = () => {
  const log = getLogger();
  log.info('This logger will share the same metadata. It will not be re-initialised');
}

Docs

Package exposes two functions

createLogger({ context = {}, logLevel = 'info', ...rest }): Logger

const log = createLogger({ context });
log.warn('Some weird warning', {example: 'whatever'})

// Will log something like
// {"example":"whatever","level":"warn",
// "message":"Some weird warning","meta":{"invokeId":"bbbf527c-5308-4d7f-a85f-597595136db5"},
// "timestamp":"2018-02-05T05:42:35.002Z"}

getLogger(): Logger

Will return already initialized worker (if exist) using process process.env._X_AMZN_TRACE_ID. Creates a new logger if _X_AMZN_TRACE_ID env variable is not defined or logger not found

createLogger({ context });

const log = getLogger();
log.info({pewpew: 42})

Logger object

Exposes all the winston methods (read docs) and also provides some aliases to set execution-wide metadata

log.setMember(any)

log.setAccount(any)

log.setCorrelation(any)

Aliases to set metadata fields

log.meta(): Object

Returns metadata object

Publish

Login (npm login) as assetchain user (check [email protected] email) and publish it

npm publish --access public

Development

Build this library using npm build - that will run eslint + prettier checks and unit tests

License

The MIT License (MIT)

Copyright © 2017 AssetChain

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.