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

`js
// 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

$3

`js
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"}
`

$3

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

`js
createLogger({ context });

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

$3

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 dev@assetchain.com.au 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.