Error Logger Middleware for Middy

Errors logging middleware for Middy.

The middleware catches thrown exceptions and rejected promises and logs them comprehensibly to the console. All logs are enriched with event and context.

It works with http-errors module and creates a proper HTTP response for them using the message and the status code.

Usage

import createError from 'http-errors';
import middy from 'middy';
import errorLogger from '@keboola/middy-error-logger';

export const handler = middy(() => {
  throw new createError.UnprocessableEntity();
});

handler
  .use(errorLogger());

This sample code writes such a stringified json to the console:

{
  "message": "Unprocessable Entity",
  "statusCode": 422,
  "stack": [
    "UnprocessableEntityError: Unprocessable Entity",
    "at Function._callee$ (/var/task/src/lambda.js:6:19)",
    "at tryCatch (/var/task/node_modules/regenerator-runtime/runtime.js:62:40)",
    "..."
  ],
  "event": {
    "resource": "/",
    "httpMethod": "GET",
    "queryStringParameters": null,
    "body": null
  },
  "context": {
    "sourceIp": "214.178.123.91",
    "userAgent": "Paw/3.1.7 (Macintosh; OS X/10.14.0) GCDHTTPRequest"
  },
  "awsRequestId": "ab022f5a-d3ad-11e8-89f6-89a425b4ca0a"
}

And return this message to the request response:

{
  "errorMessage": "Unprocessable Entity",
  "errorCode": 422,
  "requestId": "ab022f5a-d3ad-11e8-89f6-89a425b4ca0a"
}

If the error is not an instance from http-errors, the error message in the response is replaced with "Internal Error." and the status code is set to 500.