Serve S3 files through express proxy

s3proxy.js

// Example of using express to proxy files from s3.
// Works with streaming media like mp4

const AWS = require('aws-sdk')
const mime = require('mime-types')
const express = require('express')

AWS.config.update({
	secretAccessKey: '...',
	accessKeyId: '...',
})

const s3 = new AWS.S3({ params: { Bucket: 'bucketname' } })
const app = express()

AWS.Request.prototype.forwardToExpress = function forwardToExpress(res, next, key) {
	this.on('httpHeaders', function(code, headers) {
		res.status(code)
		if (code < 300) {
			const newHeaders = {
				...headers,
				'Content-Type': mime.lookup(key),
			}
			// Remove some unwanted amazon headers
			delete newHeaders['x-amz-id-2']
			delete newHeaders['x-amz-request-id']
			delete newHeaders['x-amz-meta-modified']
			res.set(newHeaders)
		}
	})
		.createReadStream()
		.on('error', next)
		.pipe(res)
}

app.get('/myfile.mp4', function(req, res, next) {
	s3.getObject({
		Bucket: 'bucketname',
		Key: 'myfile.mp4',
		Range: req.headers.range,
	}).forwardToExpress(res, next, key)
})

app.listen(8000, () => console.log('App launched on port 8000'))