Resize an image, create a thumbnail, compress and uploads to S3

s3_image_upload.go

package main

import (
	"bytes"
	"compress/gzip"
	"fmt"
	"github.com/awslabs/aws-sdk-go/aws"
	"github.com/awslabs/aws-sdk-go/aws/awsutil"
	"github.com/awslabs/aws-sdk-go/service/s3"
	"github.com/hyperboloide/pipe"
	"github.com/nfnt/resize"
	"image"
	"image/jpeg"
	"io"
	"log"
	"os"
)

func zip(r io.Reader, w io.Writer) error {
	gzw, err := gzip.NewWriterLevel(w, gzip.BestCompression)
	if err != nil {
		return err
	}
	defer gzw.Close()
	_, err = io.Copy(gzw, r)
	return err
}

func scaleImage(width uint, height uint) func(io.Reader, io.Writer) error {

	return func(r io.Reader, w io.Writer) error {
		img, _, err := image.Decode(r)
		if err != nil {
			return err
		}

		newImage := resize.Thumbnail(width, height, img, resize.Lanczos2)
		return jpeg.Encode(w, newImage, nil)
	}
}

func s3Upload(path string, body bytes.Buffer) {
	svc := s3.New(&aws.Config{
		Region: "eu-west-1",
	})

	params := &s3.PutObjectInput{
		Bucket:          aws.String("some_bucket"),
		Key:             aws.String(path),
		Body:            bytes.NewReader(body.Bytes()),
		ContentType:     aws.String("image/jpeg"),
		ContentEncoding: aws.String("gzip"),
	}
	resp, err := svc.PutObject(params)

	if awserr := aws.Error(err); awserr != nil {
		fmt.Println("Error:", awserr.Code, awserr.Message)
	} else if err != nil {
		log.Fatal(err)
	}
	fmt.Println(awsutil.StringValue(resp))
}

func main() {
	// pipe input
	in, err := os.Open("test.jpg")
	if err != nil {
		log.Fatal(err)
	}
	defer in.Close()

	// create a new pipe with a io.Reader
	pImage := pipe.New(in)

	// scale the image
	pImage.Push(scaleImage(600, 600))

	// create a tee to upload a thumbnail
	pThumb := pImage.Tee()

	// scale and compress the thumbnail
	pThumb.Push(scaleImage(160, 160), zip)

	// compresss the image
	pImage.Push(zip)

	// too bad this s3 package doesn't support stream upload yet...
	var buffImage bytes.Buffer
	pImage.To(&buffImage)
	if err := pImage.Exec(); err != nil {
		log.Fatal(err)
	}
	s3Upload("test.jpg", buffImage)

	var buffThumb bytes.Buffer
	pThumb.To(&buffThumb)
	if err := pThumb.Exec(); err != nil {
		log.Fatal(err)
	}
	s3Upload("test@thumb.jpg", buffThumb)
}