aws-lambda-fastify

Introduction

Inspired by the AWSLABS aws-serverless-express library tailor made for the Fastify web framework.

No use of internal sockets, makes use of Fastify's inject function.

Seems faster (as the name implies) than aws-serverless-express and aws-serverless-fastify 😉

👨🏻‍💻Installation

$ npm install aws-lambda-fastify

📖Example

lambda.js

const awsLambdaFastify = require('aws-lambda-fastify')
const app = require('./app')

const proxy = awsLambdaFastify(app)
// or
// const proxy = awsLambdaFastify(app, { binaryMimeTypes: ['application/octet-stream'] })

exports.handler = proxy
// or
// exports.handler = (event, context, callback) => proxy(event, context, callback)
// or
// exports.handler = (event, context) => proxy(event, context)
// or
// exports.handler = async (event, context) => proxy(event, context)

app.js

const fastify = require('fastify')

const app = fastify()
app.get('/', (request, reply) => reply.send({ hello: 'world' }))

if (require.main === module) {
  // called directly i.e. "node app"
  app.listen(3000, (err) => {
    if (err) console.error(err)
    console.log('server listening on 3000')
  })
} else {
  // required as a module => executed on aws lambda
  module.exports = app
}

When executed in your lambda function we don't need to listen to a specific port, so we just export the app in this case. The lambda.js file will use this export.

When you execute your Fastify application like always, i.e. node app.js (the detection for this could be require.main === module), you can normally listen to your port, so you can still run your Fastify function locally.

📣Hint

The original lambda event and context are passed via headers and can be used like this:

app.get('/', (request, reply) => {
  const event = JSON.parse(decodeURIComponent(request.headers['x-apigateway-event']))
  const context = JSON.parse(decodeURIComponent(request.headers['x-apigateway-context']))
  // ...
})

⚡️Some basic performance metrics

aws-lambda-fastify x 28,189 ops/sec ±4.59% (79 runs sampled)

serverless-http x 20,975 ops/sec ±4.65% (79 runs sampled)

aws-serverless-fastify x 4,042 ops/sec ±2.14% (75 runs sampled)

aws-serverless-express x 3,558 ops/sec ±4.48% (71 runs sampled)

Fastest is aws-lambda-fastify

⚠️Considerations

• For apps that may not see traffic for several minutes at a time, you could see cold starts
• Stateless only
• API Gateway has a timeout of 29 seconds, and Lambda has a maximum execution time of 15 minutes. (Using Application Load Balancer has no timeout limit, so the lambda maximum execution time is relevant)
• If you are using another web framework (Connect, Express, Koa, Restana, Sails, Hapi, Fastify, Restify) or want to use a more generic serverless proxy framework, have a look at: serverless-http