amazon-web-services - 如何使用 golang 从公共(public) s3 存储桶下载

Question

我正在实现一个从 s3 存储桶下载文件的功能。当存储桶是私有(private)的并且我设置了凭据时，这工作正常

os.Setenv("AWS_ACCESS_KEY_ID", "test")
os.Setenv("AWS_SECRET_ACCESS_KEY", "test")

但是，我公开了 s3 存储桶，如 here 中所述现在我想在没有凭据的情况下下载它。

func DownloadFromS3Bucket(bucket, item, path string) {
    file, err := os.Create(filepath.Join(path, item))
    if err != nil {
        fmt.Printf("Error in downloading from file: %v \n", err)
        os.Exit(1)
    }

    defer file.Close()

    sess, _ := session.NewSession(&aws.Config{
        Region: aws.String(constants.AWS_REGION)},
    )

    // Create a downloader with the session and custom options
    downloader := s3manager.NewDownloader(sess, func(d *s3manager.Downloader) {
        d.PartSize = 64 * 1024 * 1024 // 64MB per part
        d.Concurrency = 6
    })

    numBytes, err := downloader.Download(file,
        &s3.GetObjectInput{
            Bucket: aws.String(bucket),
            Key:    aws.String(item),
        })
    if err != nil {
        fmt.Printf("Error in downloading from file: %v \n", err)
        os.Exit(1)
    }

    fmt.Println("Download completed", file.Name(), numBytes, "bytes")
}

但现在我遇到了一个错误。

Error in downloading from file: NoCredentialProviders: no valid providers in chain. Deprecated.
    For verbose messaging see aws.Config.CredentialsChainVerboseErrors

知道如何在没有凭据的情况下下载它吗？

Answer 1

我们可以在创建 session 时设置Credentials: credentials.AnonymousCredentials。以下是工作代码。

func DownloadFromS3Bucket(bucket, item, path string) {
    file, err := os.Create(filepath.Join(path, item))
    if err != nil {
        fmt.Printf("Error in downloading from file: %v \n", err)
        os.Exit(1)
    }

    defer file.Close()

    sess, _ := session.NewSession(&aws.Config{
        Region: aws.String(constants.AWS_REGION), Credentials: credentials.AnonymousCredentials},
    )

    // Create a downloader with the session and custom options
    downloader := s3manager.NewDownloader(sess, func(d *s3manager.Downloader) {
        d.PartSize = 64 * 1024 * 1024 // 64MB per part
        d.Concurrency = 6
    })

    numBytes, err := downloader.Download(file,
        &s3.GetObjectInput{
            Bucket: aws.String(bucket),
            Key:    aws.String(item),
        })
    if err != nil {
        fmt.Printf("Error in downloading from file: %v \n", err)
        os.Exit(1)
    }

    fmt.Println("Download completed", file.Name(), numBytes, "bytes")
}