golangでawsのs3のデータをダウンロードするコード

下記を参考にした
https://docs.aws.amazon.com/sdk-for-go/api/service/s3/
https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/go/example_code/s3

package main

import (
    "fmt"
    "os"

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

func main() {
    creds := credentials.NewStaticCredentials("アクセスキー", "シークレットキー", "")

    sess := session.Must(session.NewSession(&aws.Config{
        Credentials: creds,
        Region:      aws.String("ap-northeast-1"),
    }))

    filename := "aaa.txt"

    // Create a downloader with the session and default options
    downloader := s3manager.NewDownloader(sess)

    // Create a file to write the S3 Object contents to.
    f, err := os.Create(filename)
    if err != nil {
        fmt.Println(fmt.Errorf("failed to create file %q, %v", filename, err))
        return
    }

    // Write the contents of S3 Object to the file
    n, err := downloader.Download(f, &s3.GetObjectInput{
        Bucket: aws.String("backet-name"),
        Key:    aws.String("/aaa.txt"),
    })
    if err != nil {
        fmt.Println(fmt.Errorf("failed to download file, %v", err))
        return
    }
    fmt.Printf("file downloaded, %d bytes\n", n)

}

// ついでにアップロードは下記
func upload() {

    accessKey := "your accessKey"
    privateKey := "your privateKey"
    region := "ap-northeast-1"
    fileName := "gazou.png"
    bucketName := "your bucketName"

    creds := credentials.NewStaticCredentials(accessKey, privateKey, "")
    sess := session.Must(session.NewSession(&aws.Config{
        Credentials: creds,
        Region:      aws.String(region),
    }))
    uploader := s3manager.NewUploader(sess)

    f, err := os.Open(fileName)
    if err != nil {
        log.Fatal(fmt.Errorf("failed to open file %q, %v", fileName, err))
    }
    res, err := uploader.Upload(&s3manager.UploadInput{
        Bucket: aws.String(bucketName),
        Key:    aws.String("/test/" + fileName),
        Body:   f,
    })
    if err != nil {
        fmt.Println(res)
        if err, ok := err.(awserr.Error); ok && err.Code() == request.CanceledErrorCode {
            fmt.Fprintf(os.Stderr, "upload canceled due to timeout, %v\n", err)
        } else {
            fmt.Fprintf(os.Stderr, "failed to upload object, %v\n", err)
        }
        os.Exit(1)
    }
    fmt.Println("successfully uploaded file!!")
}

exampleに、credentialsの部分の記述が見当たらなかったので、メモ的にアップしました。

それ以外はサンプル通りです。結構簡単ですね。