A dead-simple Go HTTP streamer/proxy for files hosted in a S3 bucket. NOTE 1: You will need the `AWS_ACCESS_KEY` and `AWS_SECRET_KEY` environment variables set properly in order for this script to work. NOTE 2: This creates a mini HTTP server on localhost:3001.

http_streamer.go

package main

import (
	"github.com/mitchellh/goamz/aws"
	"github.com/mitchellh/goamz/s3"
	"log"
	"net/http"
	"io"
)

func checkEnv() aws.Auth {
	log.Print("Checking for AWS_ACCESS_KEY and AWS_SECRET_KEY environment variables...")
	auth, err := aws.EnvAuth()
	if err != nil {
		panic(err.Error())
	}
	return auth
}

func streamS3File(path string, bucket *s3.Bucket, w io.Writer) int {
	log.Printf("Downloading stream at path %#v from bucket %#v...", path, bucket.Name)

	rc, err := bucket.GetReader(path)
	if err != nil {
		panic(err.Error())
	}
	defer rc.Close()

	buf := make([]byte, 8 * 1048576)
	n := 0
	total := 0
	for err == nil {
		n, err = rc.Read(buf)
		w.Write(buf[0:n])
		total += n
	}

	return total
}

func handler(w http.ResponseWriter, r *http.Request) {
	path := r.URL.Path

	streamS3File(path, bucket, w)
}

func startServing() {
	http.HandleFunc("/", handler)
    http.ListenAndServe(":3001", nil)
}

var auth aws.Auth
var client *s3.S3
var bucket *s3.Bucket

func main() {
	auth = checkEnv()
	client = s3.New(auth, aws.USWest2)
	bucket = client.Bucket("your-bucket-name")

	log.Print(bucket.Name)

	startServing()
}