# lambda-edge-server

[![npm version](https://badge.fury.io/js/lambda-edge-server.svg)](https://badge.fury.io/js/lambda-edge-server) [![](https://img.shields.io/npm/dm/lambda-edge-server.svg)](https://www.npmjs.com/package/lambda-edge-server) [![Build Status](https://api.travis-ci.com/lambda-lambda-lambda/lambda-edge-server.svg?branch=master)](https://app.travis-ci.com/github/lambda-lambda-lambda/lambda-edge-server) [![Install size](https://packagephobia.com/badge?p=lambda-edge-server)](https://packagephobia.com/result?p=lambda-edge-server) [![](https://img.shields.io/github/v/release/lambda-lambda-lambda/lambda-edge-server)](https://github.com/lambda-lambda-lambda/lambda-edge-server/releases) [![NO AI](https://raw.githubusercontent.com/nuxy/no-ai-badge/master/badge.svg)](https://github.com/nuxy/no-ai-badge)

AWS [CloudFront Lambda@Edge](https://docs.aws.amazon.com/lambda/latest/dg/lambda-edge.html) function handler emulator.

Provides a translation layer between [Node.js](https://nodejs.org) HTTP server and [Lambda](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/lambda-generating-http-responses.html) function response format.  The goal is simplify local testing without the need for complex dependencies.

## Dependencies

- [Node.js](https://nodejs.org)

## Installation

Install this package using [NPM](https://npmjs.com):

    $ npm install lambda-edge-server

## Lambda function handlers

The following `origin-request/origin-response` format is currently supported.

### Synchronous example

```javascript
/**
 * @see AWS::Serverless::Function
 */
exports.handler = function(event, context, callback) {
  const response = {
    status: '200',
    statusDescription: 'OK',
    headers: {
      'cache-control': [{
        key: 'Cache-Control',
        value: 'max-age=0'
      }],
      'content-type': [{
        key: 'Content-Type',
        value: 'text/html'
      }]
    },
    body: 'Success',
  };

  callback(null, response);
};
```

### Asynchronous example

```javascript
/**
 * @see AWS::Serverless::Function
 */
exports.handler = async function(event) {
  const response = {
    status: '200',
    statusDescription: 'OK',
    headers: {
      'cache-control': [{
        key: 'Cache-Control',
        value: 'max-age=0'
      }],
      'content-type': [{
        key: 'Content-Type',
        value: 'text/html'
      }]
    },
    body: 'Success',
  };

  return response;
};
```

## Developers

### CLI options

Launch [HTTP server instance](http://localhost:3000), run the function:

    $ npm start ./path/to/script.js

Run [ESLint](https://eslint.org/) on project sources:

    $ npm run lint

Run [Mocha](https://mochajs.org) integration tests:

    $ npm run test

## References

- [Example origin request](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/lambda-event-structure.html#example-origin-request)
- [Example origin-response](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/lambda-event-structure.html#lambda-event-structure-response)

## AWS changes starting in Node.js 24

Going forward, it is recommended that you build your L³ application using `async` handlers in anticipation of the AWS changes below.

> AWS Lambda plans to remove support for callback-based function handlers starting with Node.js 24. You will need to update this function to use an async handler to use Node.js 24 or later. For more information and to provide feedback on this change, see aws/aws-lambda-nodejs-runtime-interface-client#137

While backwards compatibity will be supported for older Node.js releases this support **will eventually be phased out** with the deprecation of `nodejs22.x` (Apr 30, 2027).

See [AWS Node.js Supported Runtimes](https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html#runtimes-supported) for support information.

## Contributions

If you fix a bug, or have a code you want to contribute, please send a pull-request with your changes. (Note: Before committing your code please ensure that you are following the [Node.js style guide](https://github.com/felixge/node-style-guide))

## Versioning

This package is maintained under the [Semantic Versioning](https://semver.org) guidelines.

## License and Warranty

This package is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.

_lambda-edge-server_ is provided under the terms of the [MIT license](http://www.opensource.org/licenses/mit-license.php)

[AWS](https://aws.amazon.com) is a registered trademark of Amazon Web Services, Inc.

## Author

[Marc S. Brooks](https://github.com/nuxy)