main.go

package main

import (
	"net/http"
	"log"
	"fmt"
	"mime/multipart"
	"bytes"
	"path/filepath"
	
	"github.com/globalsign/mgo/bson"
	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/credentials"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/s3"
)



// UploadFileToS3 saves a file to aws bucket and returns the url to the file and an error if there's any
func UploadFileToS3(s *session.Session, file multipart.File, fileHeader *multipart.FileHeader) (string, error) {
	// get the file size and read
	// the file content into a buffer
	size := fileHeader.Size
	buffer := make([]byte, size)
	file.Read(buffer)

	// create a unique file name for the file
	tempFileName := "pictures/" + bson.NewObjectId().Hex() + filepath.Ext(fileHeader.Filename)
	
	// config settings: this is where you choose the bucket,
	// filename, content-type and storage class of the file
	// you're uploading
	_, err := s3.New(s).PutObject(&s3.PutObjectInput{
		Bucket:               aws.String("test-bucket"),
		Key:                  aws.String(tempFileName),
		ACL:                  aws.String("public-read"),// could be private if you want it to be access by only authorized users
		Body:                 bytes.NewReader(buffer),
		ContentLength:        aws.Int64(int64(size)),
		ContentType:          aws.String(http.DetectContentType(buffer)),
		ContentDisposition:   aws.String("attachment"),
		ServerSideEncryption: aws.String("AES256"),
		StorageClass:         aws.String("INTELLIGENT_TIERING"),
	})
	if err != nil {
		return "", err
	}

	return tempFileName, err
}

func handler(w http.ResponseWriter, r *http.Request) {
	maxSize := int64(1024000) // allow only 1MB of file size

	err := r.ParseMultipartForm(maxSize)
	if err != nil {
		log.Println(err)
		fmt.Fprintf(w, "Image too large. Max Size: %v", maxSize)
		return
	}

	file, fileHeader, err := r.FormFile("profile_picture")
	if err != nil {
		log.Println(err)
		fmt.Fprintf(w, "Could not get uploaded file")
		return
	}
	defer file.Close()

	// create an AWS session which can be
	// reused if we're uploading many files
	s, err := session.NewSession(&aws.Config{
		Region: aws.String("us-east-2"),
		Credentials: credentials.NewStaticCredentials(
			"secret-id", // id
			"secret-key",   // secret
			""),  // token can be left blank for now
	})
	if err != nil {
		fmt.Fprintf(w, "Could not upload file")
	}

	fileName, err := UploadFileToS3(s, file, fileHeader)
	if err != nil {
		fmt.Fprintf(w, "Could not upload file")
	}

	fmt.Fprintf(w, "Image uploaded successfully: %v", fileName)
}

func main() {
	http.HandleFunc("/", handler)
	log.Println("Upload server started")
	log.Fatal(http.ListenAndServe(":8080", nil))
}