hapi-gateway

hapi-gateway is a hapi plugin that allows a hapi server to act as an API Gateway to AWS Lambda functions. hapi-gateway defines a new lambda handler type. When a lambda route handler is accessed, it invokes the backing the AWS Lambda function.

hapi-gateway allows your Lambda function code to be deployed along with your hapi server. A lambda handler can be associated with a file containing your Lambda function code. When the hapi server starts, the code is deployed to AWS (overwriting any existing Lambda function of the same name). Optionally, the Lambda function can be removed from AWS when the hapi server is shut down.

Example

The following example creates a hapi server. On server startup, a Lambda function is deployed to AWS. The Lambda can be invoked via the GET /hello-world route. When the hapi server stops, the Lambda function is automatically deleted. A SIGINT signal handler has been added to catch Control+C and gracefully shutdown the server.

'use strict';
 
const Path = require('path');
const Hapi = require('hapi');
const Gateway = require('hapi-gateway');
const server = new Hapi.Server();
 
server.connection();
server.register([
  {
    register: Gateway,
    // These are options that are applied to all lambda handlers
    options: {
      role: 'arn:aws:iam::XXXX:role/lambda_basic_execution',  // IAM role
      config: {
        accessKeyId: 'YOUR_ACCESS_KEY',                       // access key
        secretAccessKey: 'YOUR_SECRET_KEY',                   // secret key
        region: 'YOUR_REGION'                                 // region
      }
    }
  }
], (err) => {
  if (err) {
    throw err;
  }
 
  server.route([
    {
      // This deploys the lambda function code in deploy.source at startup.
      // The function can then be invoked via this route. When the server
      // shuts down, the lambda function is deleted.
      method: 'GET',
      path: '/hello-world',
      config: {
        handler: {
          lambda: {
            name: 'hello-world',
            deploy: {
              source: Path.join(__dirname, 'hello-world.js'),
              export: 'handler',
              teardown: true
            }
          }
        }
      }
    }
  ]);
 
  server.start((err) => {
    if (err) {
      throw err;
    }
 
    // Handle Control+C so the server can be stopped and lambdas torn down
    process.on('SIGINT', () => {
      console.log('Shutting down server...');
      server.stop((err) => {
        if (err) {
          throw err;
        }
 
        process.exit(0);
      });
    });
 
    console.log(`Server started at ${server.info.uri}`);
  });
});

The corresponding Lambda function code, which is loaded from 'hello-world.js', is shown below:

'use strict';
 
module.exports.handler = function handler (event, context, callback) {
  callback(null, 'hello world!');
};

API

On plugin registration, hapi-gateway defines a new handler type named lambda. These routes are configured using an object with the following schema.

• name (string) - The name of the Lambda function to invoke.
• setup(request, callback) (function) - An optional function that creates the request payload sent to the Lambda function. request is the hapi request object associated with the route. Once setup() is complete, callback() is invoked with an error argument, followed by the payload to send to the Lambda function. If a custom setup() function is not provided, a default function is used which outputs a JSON string representing much of hapi request object.
• complete(err, response, request, reply) (function) - An optional function that converts the Lambda function's response into a client reply. err and response are the error and response from the Lambda function. request and reply are the hapi request and reply objects.
• local (boolean) - If true, the Lambda function will not be deployed to or invoked on AWS. Instead, the function will be run locally. This is useful for applying at the plugin level to test everything locally. Defaults to false.
• config (object) - An optional configuration object passed directly to the Aws.Lambda() constructor.
• role (string) - An AWS role with permission to execute the Lambda.
• deploy (object) - An optional object used to deploy code as an AWS Lambda. Code is deployed at server startup using an 'onPreStart' extension point. If this object is not provided, then the user is responsible for deploying the code prior to starting the server. If this object is present, it must adhere to the following schema.
  • source (string) - The path to a file containing Lambda function code.
  • export (string) - The name of the exported function in source that acts as the Lambda function's entry point.
  • timeout (number) - The execution timeout of the Lambda function in seconds. Defaults to three seconds.
  • memory (number) - The amount of memory, in MB, given to the Lambda function. Must be a multiple of 64MB. Defaults to 128MB.
  • teardown (boolean) - If true, the deployed Lambda function is deleted when the hapi server shuts down. The deletion is done during an 'onPostStop' extension point. Defaults to false, meaning the deployed function is not deleted.
  • exclude (array) - An optional array of strings representing modules to exclude from the bundle. This array is passed to Browserify. This option is essential when bundling code that uses the 'aws-sdk' module. You can bundle 'aws-sdk' via the files option, or rely on the version that is natively available on Lambda.
  • files (array) - An optional array of strings and/or objects indicating additional files (such as standalone executables) to include in the zip archive. Strings specify file and directory paths. Objects should have name and data properties which are used as the file name and contents in the zip archive.

It is worth noting that the same options can be provided to the plugin's register() function. The configuration for each route is used by merging the module defaults, the plugin registration options, and the individual route options (in order of increasing priority).