@middy/core

What is @middy/core?

@middy/core is a middleware engine for AWS Lambda that helps you simplify and streamline your Lambda functions by allowing you to compose them using reusable middleware. It provides a way to handle common concerns such as input validation, error handling, and response formatting in a modular and reusable manner.

What are @middy/core's main functionalities?

Middleware Composition

This feature allows you to compose your Lambda function using multiple middleware. Each middleware can perform specific tasks and then pass control to the next middleware in the chain.

const middy = require('@middy/core');
const middleware1 = (request, next) => { console.log('Middleware 1'); next(); };
const middleware2 = (request, next) => { console.log('Middleware 2'); next(); };
const handler = middy((event, context) => { return { message: 'Hello World' }; })
  .use(middleware1)
  .use(middleware2);

exports.handler = handler;

Error Handling

This feature allows you to handle errors in a centralized manner. The errorHandler middleware catches any errors thrown by the Lambda function and sets a custom response.

const middy = require('@middy/core');
const errorHandler = (request, next) => { try { next(); } catch (err) { console.error(err); request.response = { statusCode: 500, body: 'Internal Server Error' }; } };
const handler = middy((event, context) => { throw new Error('Something went wrong'); })
  .use(errorHandler);

exports.handler = handler;

Input Validation

This feature allows you to validate the input to your Lambda function. The inputValidator middleware checks if the input is valid and throws an error if it is not.

const middy = require('@middy/core');
const inputValidator = (request, next) => { if (!request.event.body) { throw new Error('Invalid input'); } next(); };
const handler = middy((event, context) => { return { message: 'Input is valid' }; })
  .use(inputValidator);

exports.handler = handler;

Other packages similar to @middy/core

serverless-middleware

serverless-middleware is a middleware framework for AWS Lambda functions, similar to @middy/core. It allows you to compose your Lambda functions using middleware, but it is less mature and has fewer built-in middleware options compared to @middy/core.

lambda-middleware

lambda-middleware is another middleware framework for AWS Lambda functions. It provides a similar middleware composition model as @middy/core but focuses more on simplicity and ease of use. It has a smaller community and fewer plugins compared to @middy/core.

express

Express is a web application framework for Node.js that provides a robust set of features for web and mobile applications. While not specifically designed for AWS Lambda, it can be used in conjunction with AWS Lambda to handle HTTP requests and middleware. It is more feature-rich and has a larger community compared to @middy/core.

README

Middy Core

Core component of the middy framework, the stylish Node.js middleware engine for AWS Lambda

You can read the documentation at: https://middy.js.org

Install

To install middy you can use NPM:

npm install --save @middy/core

Documentation and examples

For documentation and examples, refers to the main Middy monorepo on GitHub or Middy official website.

Contributing

Everyone is very welcome to contribute to this repository. Feel free to raise issues or to submit Pull Requests.

License

Licensed under MIT License. Copyright (c) 2017-2022 Luciano Mammino, will Farrell, and the Middy team.