lambda-response

Express-like API for sending responses from Lambda Integration Proxy to API Gateway.

Includes a CLI tool and express middleware for local development.

Install

npm install @jschr/lambda-response

Usage

const { Response } = require('@jschr/lambda-response')

export default function handler(event, context) {
  const res = new Response()

  context.succeed(res.send('OK'))
  // => { statusCode: 200, body: 'OK' }

  context.succeed(res.json({ foo: bar }))
  // => { statusCode: 200, body: '{"foo":"bar"}' }

  context.succeed(res.status(404).json({ message: 'Not found.' }))
  // => { statusCode: 404, body: '{"message":"Not found."}' }

  context.succeed(res.redirect('https://github.com'))
  // => { statusCode: 302, headers: { Location: 'https://github.com'} } }
}

Even more express-like with async/await:

const { Response } = require('@jschr/lambda-response')

async function route(req, res) {
  const data = await someAsyncFunction(req.query.id)

  if (data) {
    res.json(data)
  } else {
    res.status(404).json({ message: 'Not found'. })
  }
}

export default function handler(event, context) {
  const req = { query: event.queryStringParameters || {} }
  const res = new Response()

  route(req, res)
    .then(() => context.succeed(res))
    .catch(context.fail)
}

Headers

Default headers can be passed when creating a new response:

const headers = { 'Content-Type': 'application/json' }
const res = new Response({ headers })

Or on an instance:

const res = new Response()
const headers = { 'Content-Type': 'application/json' }
res.set(headers)

CORS

CORS is enabled by default. You can pass in cors options when creating a new response:

const cors = { origin: 'example.com', methods: ['GET'], headers: ['X-Api-Key'] }
const res = new Response({ cors })

Check out the tests for more examples.

CLI

You can use the CLI for local development. If you've installed @jschr/lambda-response globally:

$ lambda-response foo/bar.default --port 8080

Where foo/bar is the path to your lambda handler and default is the exported function.

Middleware

For advanced use cases you can use the lambda-response express middleware:

import * as express from 'express'
import { middleware } from '@jschr/lambda-response'

import handler from './foo/bar'

const app = express()

app.use(middleware(handler))

app.listen(8080)