How to Stream File Uploads to AWS S3 Using Go?

package main

import (
    "fmt"
    "os"

    "github.com/aws/aws-sdk-go/aws/credentials"

    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/s3/s3manager"
)

const (
    filename      = "file_name.zip"
    myBucket      = "myBucket"
    myKey         = "file_name.zip"
    accessKey     = ""
    accessSecret  = ""
)

func main() {
    var awsConfig *aws.Config
    if accessKey == "" || accessSecret == "" {
        //load default credentials
        awsConfig = &aws.Config{
            Region: aws.String("us-west-2"),
        }
    } else {
        awsConfig = &aws.Config{
            Region:      aws.String("us-west-2"),
            Credentials: credentials.NewStaticCredentials(accessKey, accessSecret, ""),
        }
    }

    // The session the S3 Uploader will use
    sess := session.Must(session.NewSession(awsConfig))

    // Create an uploader with the session and default options
    //uploader := s3manager.NewUploader(sess)

    // Create an uploader with the session and custom options
    uploader := s3manager.NewUploader(sess, func(u *s3manager.Uploader) {
        u.PartSize = 5 * 1024 * 1024 // The minimum/default allowed part size is 5MB
        u.Concurrency = 2            // default is 5
    })

    //open the file
    f, err := os.Open(filename)
    if err != nil {
        fmt.Printf("failed to open file %q, %v", filename, err)
        return
    }
    //defer f.Close()

    // Upload the file to S3.
    result, err := uploader.Upload(&s3manager.UploadInput{
        Bucket: aws.String(myBucket),
        Key:    aws.String(myKey),
        Body:   f,
    })

    //in case it fails to upload
    if err != nil {
        fmt.Printf("failed to upload file, %v", err)
        return
    }
    fmt.Printf("file uploaded to, %s\n", result.Location)
}