Setting Object Ownership when you create a bucket - Amazon Simple Storage Service

Setting Object Ownership when you create a bucket

When you create a bucket, you can configure S3 Object Ownership. To set Object Ownership for an existing bucket, see Setting Object Ownership on an existing bucket.

S3 Object Ownership is an Amazon S3 bucket-level setting that you can use to disable access control lists (ACLs) and take ownership of every object in your bucket, simplifying access management for data stored in Amazon S3. By default, S3 Object Ownership is set to the Bucket owner enforced setting, and ACLs are disabled for new buckets. With ACLs disabled, the bucket owner owns every object in the bucket and manages access to data exclusively by using access-management policies. We recommend that you keep ACLs disabled, except in unusual circumstances where you must control access for each object individually.

Object Ownership has three settings that you can use to control ownership of objects uploaded to your bucket and to disable or enable ACLs:

ACLs disabled

  • Bucket owner enforced (default) – ACLs are disabled, and the bucket owner automatically owns and has full control over every object in the bucket. ACLs no longer affect permissions to data in the S3 bucket. The bucket uses policies to define access control.

ACLs enabled

  • Bucket owner preferred – The bucket owner owns and has full control over new objects that other accounts write to the bucket with the bucket-owner-full-control canned ACL.

  • Object writer – The AWS account that uploads an object owns the object, has full control over it, and can grant other users access to it through ACLs.

Permissions: To apply the Bucket owner enforced setting or the Bucket owner preferred setting, you must have the following permissions: s3:CreateBucket and s3:PutBucketOwnershipControls. No additional permissions are needed when creating a bucket with the Object writer setting applied. For more information about Amazon S3 permissions, see Actions, resources, and condition keys for Amazon S3 in the Service Authorization Reference.

Important

A majority of modern use cases in Amazon S3 no longer require the use of ACLs, and we recommend that you disable ACLs except in unusual circumstances where you need to control access for each object individually. With Object Ownership, you can disable ACLs and rely on policies for access control. When you disable ACLs, you can easily maintain a bucket with objects uploaded by different AWS accounts. You, as the bucket owner, own all the objects in the bucket and can manage access to them using policies.

  1. Sign in to the AWS Management Console and open the Amazon S3 console at https://console.aws.amazon.com/s3/.

  2. In the navigation bar on the top of the page, choose the name of the currently displayed AWS Region. Next, choose the Region in which you want to create a bucket.

    Note

    To minimize latency and costs and address regulatory requirements, choose a Region close to you. Objects stored in a Region never leave that Region unless you explicitly transfer them to another Region. For a list of Amazon S3 AWS Regions, see AWS service endpoints in the Amazon Web Services General Reference.

  3. In the left navigation pane, choose Buckets.

  4. Choose Create bucket.

    The Create bucket page opens.

  5. Under General configuration, view the AWS Region where your bucket will be created.

  6. Under Bucket type, choose General purpose.

  7. For Bucket name, enter a name for your bucket.

    The bucket name must:

    • Be unique within a partition. A partition is a grouping of Regions. AWS currently has three partitions: aws (Standard Regions), aws-cn (China Regions), and aws-us-gov (AWS GovCloud (US) Regions).

    • Be between 3 and 63 characters long.

    • Consist only of lowercase letters, numbers, dots (.), and hyphens (-). For best compatibility, we recommend that you avoid using dots (.) in bucket names, except for buckets that are used only for static website hosting.

    • Begin and end with a letter or number.

    After you create the bucket, you cannot change its name. For more information about naming buckets, see Bucket naming rules.

    Important

    Avoid including sensitive information, such as account numbers, in the bucket name. The bucket name is visible in the URLs that point to the objects in the bucket.

  8. AWS Management Console allows you to copy an existing bucket's settings to your new bucket. If you do not want to copy the settings of an existing bucket, skip to the next step.

    Note

    This option:

    • Is not available in the AWS CLI and is only available in console

    • Is not available for directory buckets

    • Does not copy the bucket policy from the existing bucket to the new bucket

    To copy an existing bucket's settings, under Copy settings from existing bucket, select Choose bucket. The Choose bucket window opens. Find the bucket with the settings that you would like to copy, and select Choose bucket. The Choose bucket window closes, and the Create bucket window re-opens.

    Under Copy settings from existing bucket, you will now see the name of the bucket you selected. You will also see a Restore defaults option that you can use to remove the copied bucket settings. Review the remaining bucket settings, on the Create bucket page. You will see that they now match the settings of the bucket that you selected. You can skip to the final step.

  9. Under Object Ownership, to disable or enable ACLs and control ownership of objects uploaded in your bucket, choose one of the following settings:

    ACLs disabled

    • Bucket owner enforced (default) – ACLs are disabled, and the bucket owner automatically owns and has full control over every object in the bucket. ACLs no longer affect access permissions to data in the S3 bucket. The bucket uses policies exclusively to define access control.

      By default, ACLs are disabled. A majority of modern use cases in Amazon S3 no longer require the use of ACLs. We recommend that you keep ACLs disabled, except in unusual circumstances where you must control access for each object individually. For more information, see Controlling ownership of objects and disabling ACLs for your bucket.

    ACLs enabled

    • Bucket owner preferred – The bucket owner owns and has full control over new objects that other accounts write to the bucket with the bucket-owner-full-control canned ACL.

      If you apply the Bucket owner preferred setting, to require all Amazon S3 uploads to include the bucket-owner-full-control canned ACL, you can add a bucket policy that allows only object uploads that use this ACL.

    • Object writer – The AWS account that uploads an object owns the object, has full control over it, and can grant other users access to it through ACLs.

    Note

    The default setting is Bucket owner enforced. To apply the default setting and keep ACLs disabled, only the s3:CreateBucket permission is needed. To enable ACLs, you must have the s3:PutBucketOwnershipControls permission.

  10. Under Block Public Access settings for this bucket, choose the Block Public Access settings that you want to apply to the bucket.

    By default, all four Block Public Access settings are enabled. We recommend that you keep all settings enabled, unless you know that you need to turn off one or more of them for your specific use case. For more information about blocking public access, see Blocking public access to your Amazon S3 storage.

    Note

    To enable all Block Public Access settings, only the s3:CreateBucket permission is required. To turn off any Block Public Access settings, you must have the s3:PutBucketPublicAccessBlock permission.

  11. (Optional) Under Bucket Versioning, you can choose if you wish to keep variants of objects in your bucket. For more information about versioning, see Using versioning in S3 buckets.

    To disable or enable versioning on your bucket, choose either Disable or Enable.

  12. (Optional) Under Tags, you can choose to add tags to your bucket. Tags are key-value pairs used to categorize storage.

    To add a bucket tag, enter a Key and optionally a Value and choose Add Tag.

  13. Under Default encryption, choose Edit.

  14. To configure default encryption, under Encryption type, choose one of the following:

    • Amazon S3 managed key (SSE-S3)

    • AWS Key Management Service key (SSE-KMS)

      Important

      If you use the SSE-KMS option for your default encryption configuration, you are subject to the requests per second (RPS) quota of AWS KMS. For more information about AWS KMS quotas and how to request a quota increase, see Quotas in the AWS Key Management Service Developer Guide.

    Buckets and new objects are encrypted with server-side encryption with an Amazon S3 managed key as the base level of encryption configuration. For more information about default encryption, see Setting default server-side encryption behavior for Amazon S3 buckets.

    For more information about using Amazon S3 server-side encryption to encrypt your data, see Using server-side encryption with Amazon S3 managed keys (SSE-S3).

  15. If you chose AWS Key Management Service key (SSE-KMS), do the following:

    1. Under AWS KMS key, specify your KMS key in one of the following ways:

      • To choose from a list of available KMS keys, choose Choose from your AWS KMS keys, and choose your KMS key from the list of available keys.

        Both the AWS managed key (aws/s3) and your customer managed keys appear in this list. For more information about customer managed keys, see Customer keys and AWS keys in the AWS Key Management Service Developer Guide.

      • To enter the KMS key ARN, choose Enter AWS KMS key ARN, and enter your KMS key ARN in the field that appears.

      • To create a new customer managed key in the AWS KMS console, choose Create a KMS key.

        For more information about creating an AWS KMS key, see Creating keys in the AWS Key Management Service Developer Guide.

      Important

      You can use only KMS keys that are available in the same AWS Region as the bucket. The Amazon S3 console lists only the first 100 KMS keys in the same Region as the bucket. To use a KMS key that is not listed, you must enter your KMS key ARN. If you want to use a KMS key that is owned by a different account, you must first have permission to use the key and then you must enter the KMS key ARN. For more information on cross account permissions for KMS keys, see Creating KMS keys that other accounts can use in the AWS Key Management Service Developer Guide. For more information on SSE-KMS, see Specifying server-side encryption with AWS KMS (SSE-KMS).

      When you use an AWS KMS key for server-side encryption in Amazon S3, you must choose a symmetric encryption KMS key. Amazon S3 supports only symmetric encryption KMS keys and not asymmetric KMS keys. For more information, see Identifying symmetric and asymmetric KMS keys in the AWS Key Management Service Developer Guide.

      For more information about creating an AWS KMS key, see Creating keys in the AWS Key Management Service Developer Guide. For more information about using AWS KMS with Amazon S3, see Using server-side encryption with AWS KMS keys (SSE-KMS).

    2. When you configure your bucket to use default encryption with SSE-KMS, you can also enable S3 Bucket Keys. S3 Bucket Keys lower the cost of encryption by decreasing request traffic from Amazon S3 to AWS KMS. For more information, see Reducing the cost of SSE-KMS with Amazon S3 Bucket Keys.

      To use S3 Bucket Keys, under Bucket Key, choose Enable.

  16. (Optional) If you want to enable S3 Object Lock, do the following:

    1. Choose Advanced settings.

      Important

      Enabling Object Lock also enables versioning for the bucket. After enabling you must configure the Object Lock default retention and legal hold settings to protect new objects from being deleted or overwritten.

    2. If you want to enable Object Lock, choose Enable, read the warning that appears, and acknowledge it.

    For more information, see Using S3 Object Lock.

    Note

    To create an Object Lock enabled bucket, you must have the following permissions: s3:CreateBucket, s3:PutBucketVersioning and s3:PutBucketObjectLockConfiguration.

  17. Choose Create bucket.

To set Object Ownership when you create a new bucket, use the create-bucket AWS CLI command with the --object-ownership parameter.

This example applies the Bucket owner enforced setting for a new bucket using the AWS CLI:

aws s3api create-bucket --bucket  DOC-EXAMPLE-BUCKET --region us-east-1 --object-ownership BucketOwnerEnforced
Important

If you don’t set Object Ownership when you create a bucket by using the AWS CLI, the default setting will be ObjectWriter (ACLs enabled).

This example sets the Bucket owner enforced setting for a new bucket using the AWS SDK for Java:

    // Build the ObjectOwnership for CreateBucket
    CreateBucketRequest createBucketRequest = CreateBucketRequest.builder()
            .bucket(bucketName)
            .objectOwnership(ObjectOwnership.BucketOwnerEnforced)
            .build()

     // Send the request to Amazon S3 
     s3client.createBucket(createBucketRequest);

To use the AWS::S3::Bucket AWS CloudFormation resource to set Object Ownership when you create a new bucket, see OwnershipControls within AWS::S3::Bucket in the AWS CloudFormation User Guide.

To apply the Bucket owner enforced setting for S3 Object Ownership, use the CreateBucket API operation with the x-amz-object-ownership request header set to BucketOwnerEnforced. For information and examples, see CreateBucket in the Amazon Simple Storage Service API Reference.

Next steps: After you apply the Bucket owner enforced or bucket owner preferred settings for Object Ownership, you can further take the following steps:

  • Bucket owner enforced – Require that all new buckets are created with ACLs disabled by using an IAM or Organizations policy.

  • Bucket owner preferred – Add an S3 bucket policy to require the bucket-owner-full-control canned ACL for all object uploads to your bucket.