Documentation

Overview

Package s3 provides the client and types for making API requests to Amazon Simple Storage Service.

See https://docs.aws.amazon.com/goto/WebAPI/s3-2006-03-01 for more information on this service.

See s3 package documentation for more information. https://docs.aws.amazon.com/sdk-for-go/api/service/s3/

Using the Client

To use the client for Amazon Simple Storage Service you will first need to create a new instance of it.

When creating a client for an AWS service you'll first need to have a Session already created. The Session provides configuration that can be shared between multiple service clients. Additional configuration can be applied to the Session and service's client when they are constructed. The aws package's Config type contains several fields such as Region for the AWS Region the client should make API requests too. The optional Config value can be provided as the variadic argument for Sessions and client creation.

Once the service's client is created you can use it to make API requests the AWS service. These clients are safe to use concurrently.

// Create a session to share configuration, and load external configuration.
sess := session.Must(session.NewSession())

// Create the service's client with the session.
svc := s3.New(sess)

See the SDK's documentation for more information on how to use service clients. https://docs.aws.amazon.com/sdk-for-go/api/

See aws package's Config type for more information on configuration options. https://docs.aws.amazon.com/sdk-for-go/api/aws/#Config

See the Amazon Simple Storage Service client S3 for more information on creating the service's client. https://docs.aws.amazon.com/sdk-for-go/api/service/s3/#New

Once the client is created you can make an API request to the service. Each API method takes a input parameter, and returns the service response and an error.

The API method will document which error codes the service can be returned by the operation if the service models the API operation's errors. These errors will also be available as const strings prefixed with "ErrCode".

result, err := svc.AbortMultipartUpload(params)
if err != nil {
    // Cast err to awserr.Error to handle specific error codes.
    aerr, ok := err.(awserr.Error)
    if ok && aerr.Code() == <error code to check for> {
        // Specific error code handling
    }
    return err
}

fmt.Println("AbortMultipartUpload result:")
fmt.Println(result)

Using the Client with Context

The service's client also provides methods to make API requests with a Context value. This allows you to control the timeout, and cancellation of pending requests. These methods also take request Option as variadic parameter to apply additional configuration to the API request.

ctx := context.Background()

result, err := svc.AbortMultipartUploadWithContext(ctx, params)

See the request package documentation for more information on using Context pattern with the SDK. https://docs.aws.amazon.com/sdk-for-go/api/aws/request/

Upload Managers

The s3manager package's Uploader provides concurrent upload of content to S3 by taking advantage of S3's Multipart APIs. The Uploader also supports both io.Reader for streaming uploads, and will also take advantage of io.ReadSeeker for optimizations if the Body satisfies that type. Once the Uploader instance is created you can call Upload concurrently from multiple goroutines safely.

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

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

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

// Upload the file to S3.
result, err := uploader.Upload(&s3manager.UploadInput{
    Bucket: aws.String(myBucket),
    Key:    aws.String(myString),
    Body:   f,
})
if err != nil {
    return fmt.Errorf("failed to upload file, %v", err)
}
fmt.Printf("file uploaded to, %s\n", aws.StringValue(result.Location))

See the s3manager package's Uploader type documentation for more information. https://docs.aws.amazon.com/sdk-for-go/api/service/s3/s3manager/#Uploader

Download Manager

The s3manager package's Downloader provides concurrently downloading of Objects from S3. The Downloader will write S3 Object content with an io.WriterAt. Once the Downloader instance is created you can call Upload concurrently from multiple goroutines safely.

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

// 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 {
    return fmt.Errorf("failed to create file %q, %v", filename, err)
}

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

See the s3manager package's Downloader type documentation for more information. https://docs.aws.amazon.com/sdk-for-go/api/service/s3/s3manager/#Downloader

Get Bucket Region

GetBucketRegion will attempt to get the region for a bucket using a region hint to determine which AWS partition to perform the query on. Use this utility to determine the region a bucket is in.

sess := session.Must(session.NewSession())

bucket := "my-bucket"
region, err := s3manager.GetBucketRegion(ctx, sess, bucket, "us-west-2")
if err != nil {
    if aerr, ok := err.(awserr.Error); ok && aerr.Code() == "NotFound" {
         fmt.Fprintf(os.Stderr, "unable to find bucket %s's region not found\n", bucket)
    }
    return err
}
fmt.Printf("Bucket %s is in %s region\n", bucket, region)

See the s3manager package's GetBucketRegion function documentation for more information https://docs.aws.amazon.com/sdk-for-go/api/service/s3/s3manager/#GetBucketRegion

S3 Crypto Client

The s3crypto package provides the tools to upload and download encrypted content from S3. The Encryption and Decryption clients can be used concurrently once the client is created.

sess := session.Must(session.NewSession())

// Create the decryption client.
svc := s3crypto.NewDecryptionClient(sess)

// The object will be downloaded from S3 and decrypted locally. By metadata
// about the object's encryption will instruct the decryption client how
// decrypt the content of the object. By default KMS is used for keys.
result, err := svc.GetObject(&s3.GetObjectInput {
    Bucket: aws.String(myBucket),
    Key: aws.String(myKey),
})

See the s3crypto package documentation for more information. https://docs.aws.amazon.com/sdk-for-go/api/service/s3/s3crypto/

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