s3-object-response

Middy s3-object-response middleware

S3 object response middleware for the middy framework, the stylish Node.js middleware engine for AWS Lambda

** This middleware is a Proof of Concept and requires real world testing before use, not recommended for production **

Fetches S3 object as a stream and writes back to s3 object response.

Install

To install this middleware you can use NPM:

npm install --save @middy/s3-object-response

Options

• bodyType (string) (required): How to pass in the s3 object through the handler. Can be stream or promise.
• AwsClient (object) (default AWS.S3): AWS.STS class constructor (e.g. that has been instrumented with AWS XRay). Must be from aws-sdk v2.
• awsClientOptions (object) (optional): Options to pass to AWS.STS class constructor.
• awsClientCapture (function) (optional): Enable XRay by passing captureAWSClient from aws-xray-sdk in.
• httpsCapture (function) (optional): Enable XRay by passing captureHTTPsGlobal from aws-xray-sdk in.
• disablePrefetch (boolean) (default false): On cold start requests will trigger early if they can. Setting awsClientAssumeRole disables prefetch.

NOTES:

• The response from the handler must match the allowed parameters for S3.writeGetObjectResponse, excluding RequestRoute and RequestToken.
• Lambda is required to have IAM permission for s3-object-lambda:WriteGetObjectResponse

Sample usage

Stream

import zlib from 'zlib'
import middy from '@middy/core'
import s3ObjectResponse from '@middy/s3-object-response'

const handler = middy((event, context) => {
  const readStream = context.s3Object
  const transformStream = zlib.createBrotliCompress()
  return {
    Body: readStream.pipe(transformStream)
  }
})

handler
  .use(s3ObjectResponse({
    bodyType: 'stream'
  }))

Promise

import zlib from 'zlib'
import middy from '@middy/core'
import s3ObjectResponse from '@middy/s3-object-response'

const handler = middy(async (event, context) => {
  let body = await context.s3Object
  // change body
  return {
    Body: JSON.stringify(body)
  }
})

handler
  .use(s3ObjectResponse({
    bodyType: 'promise'
  }))

Middy documentation and examples

For more documentation and examples, refers to the main Middy monorepo on GitHub or Middy official website.

Contributing

Everyone is very welcome to contribute to this repository. Feel free to raise issues or to submit Pull Requests.

License

Licensed under MIT License. Copyright (c) 2017-2021 Luciano Mammino, will Farrell, and the Middy team.