lambda-lambda-lambda

lambda-lambda-lambda

AWS Lambda@Edge serverless application router.

Features

• Routes and URI resource support.
• Local/Globally scoped middleware.
• Request/Response handling API.
• Lightweight/cost effective solution.

Dependencies

• AWS SAM CLI
• Node.js

Installation

Install package dependencies using NPM.

$ npm install lambda-lambda-lambda

Usage

Lambda function

Unless your application requires complex routing, route handlers can be defined within the Lambda function scope.

// .. sam-app/src/app.js

'use strict';

// Load module.
const Router = require('lambda-lambda-lambda');

/**
 * @see AWS::Serverless::Function
 */
exports.handler = (event, context, callback) => {
  const {request, response} = event.Records[0].cf;

  const router = new Router(request, response);
  router.setPrefix('/api'); // optional

  // Middleware (order is important).
  router.use(function(req, res, next) {
    if (req.method() === 'CONNECT') {
      res.status(405).send();
    } else {
      next();
    }
  });

  // Send root response.
  router.get('/', function(req, res) {
    res.status(501).send();
  });

  // .. everything else.
  router.default(function(req, res) {
    res.status(404).send();
  });

  callback(null, router.response());
};

Common methods

Router

Method	Description
router.setPrefix(path)	Set URI path prefix.
router.use(func)	Load the Route (e.g. Middleware) handler.
router.get(path, func)	Handle HTTP GET requests.
router.put(path, func)	Handle HTTP PUT requests.
router.patch(path, func)	Handle HTTP PATCH requests.
router.post(path, func)	Handle HTTP POST requests.
router.delete(path, func)	Handle HTTP DELETE requests.
router.default(func)	Set router fallback (default route).
router.response()	Return the AWS response object.

Request

Method	Description
req.is(mimeType)	Check Accept matches the given value.
req.header(name)	Return value for given HTTP header name.
req.getHeaders()	Return the headers of the request.
req.method()	Return the HTTP method of the request.
req.uri()	Return the relative path of the requested object.
req.clientIp()	Return the HTTP client IP (remote address).
req.param()	Return the HTTP base64 body data as object.
req.queryString()	Return the query string, if any, in the request.
req.body()	Return the base64-encoded body data.

Response

Method	Description
res.setHeader(path)	Set HTTP response header.
res.status(code).send(body)	Send the HTTP response as text.
res.status(code).json(data)	Send the HTTP response as JSON.

Complex routing

Route handler

// .. sam-app/src/routes/foo.js

'use strict';

// Load module.
const contentTypeHeader = require('middleware/ContentTypeHeader');

/**
 * @export {Object}
 */
module.exports = {
  middleware: [contentTypeHeader],

  /**
   * GET /api/foo
   */
  index (req, res) {
    res.status(200).send('Lambda, Lambda, Lambda');
  },

  /**
   * PUT /api/foo
   */
  create (req, res) {
    res.status(201).send();
  },

  /**
   * PATCH /api/foo
   */
  update (req, res) {
    res.status(204).send();
  },

  /**
   * DELETE /api/foo
   */
  delete (req, res) {
    res.status(410).send();
  },

  /**
   * POST /api/foo
   */
  submit (req, res) {
    res.status(200).send();
  }
};

Resource handler

// .. sam-app/src/routes/foo/bar.js

'use strict';

/**
 * @export {Object}
 */
module.exports = {
  resource: true,

  /**
   * GET /api/foo/bar/<resourceId>
   */
  get (req, res, id) {
    res.setHeader('Content-Type', 'application/json');
    res.status(200).json({and: 'Omega Mu'});
  },

  /**
   * PUT /api/foo/bar/<resourceId>
   */
  put (req, res, id) {
    res.status(201).send();
  },

  /**
   * PATCH /api/foo/bar/<resourceId>
   */
  patch (req, res, id) {
    res.status(204).send();
  },

  /**
   * DELETE /api/foo/bar/<resourceId>
   */
  delete (req, res, id) {
    res.status(410).send();
  },

  /**
   * POST /api/foo/bar/<resourceId>
   */
  post (req, res, id) {
    res.status(200).send();
  }
};

Mixed Route/Resource handler

// .. sam-app/src/routes/foo.js

'use strict';

/**
 * @export {Object}
 */
module.exports = {
  resource: ['get', 'put', 'patch', 'submit'],

  /**
   * GET /api/foo
   */
  index (req, res) {
    res.setHeader('Content-Type', 'text/html');
    res.status(200).send('Lambda, Lambda, Lambda');
  },

  /**
   * GET /api/foo/<resourceId>
   */
  get (req, res, id) {
    res.setHeader('Content-Type', 'application/json');
    res.status(200).json({and: 'Omega Mu'});
  },

  /**
   * PUT /api/foo
   */
  create (req, res) {
    res.status(201).send();
  },

  /**
   * PUT /api/foo/<resourceId>
   */
  put (req, res, id) {
    res.status(201).send();
  },

  /**
   * PATCH /api/foo
   */
  update (req, res) {
    res.status(204).send();
  },

  /**
   * PATCH /api/foo/<resourceId>
   */
  patch (req, res, id) {
    res.status(204).send();
  },

  /**
   * DELETE /api/foo
   */
  delete (req, res) {
    res.status(410).send();
  },

  /**
   * POST /api/foo/<resourceId>
   */
  submit (req, res, id) {
    res.status(200).send();
  }
};

Middleware

// .. sam-app/src/middleware/ContentTypeHeader.js

'use strict';

/**
 * Middleware to send Content-Type header.
 */
module.exports = (req, res, next) => {
  res.setHeader('Content-Type', 'text/html');

  next();
};

App Example

A deployable application has been provided with this package. In order to successfully deploy you must have set-up your AWS Config and have created an IAM user with the following policies:

• IAMFullAccess
• AmazonS3FullAccess
• CloudFrontFullAccess
• AWSCloudFormationFullAccess
• AWSLambda_FullAccess

WARNING: The policies above are provided to ensure a successful application deployment. It is recommended that you adjust these policies to meet the security requirements of your Lambda application. They should NOT be used in a Production environment.

Developers

CLI options

Run ESLint on project sources:

$ npm run lint

Generate documentation using JSDoc:

$ npm run gendoc

Run Mocha integration tests:

$ npm run test

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)

Versioning

This package is maintained under the Semantic Versioning 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-lambda-lambda is provided under the terms of the MIT license

AWS is a registered trademark of Amazon Web Services, Inc.

Author

Marc S. Brooks