AWS::S3::BucketPolicy - AWS CloudFormation
SyntaxPropertiesExamples

AWS::S3::BucketPolicy

Applies an Amazon S3 bucket policy to an Amazon S3 bucket. If you are using an identity other than the root user of the AWS account that owns the bucket, the calling identity must have the PutBucketPolicy permissions on the specified bucket and belong to the bucket owner's account in order to use this operation.

If you don't have PutBucketPolicy permissions, Amazon S3 returns a 403 Access Denied error. If you have the correct permissions, but you're not using an identity that belongs to the bucket owner's account, Amazon S3 returns a 405 Method Not Allowed error.

Important

As a security precaution, the root user of the AWS account that owns a bucket can always use this operation, even if the policy explicitly denies the root user the ability to perform this action.

When using the AWS::S3::BucketPolicy resource, you can create, update, and delete bucket policies for S3 buckets located in regions different from the stack's region. This cross-region bucket policy modification functionality is supported for backward compatibility with existing workflows.

Important

If the DeletionPolicy attribute is not specified or set to Delete, the bucket policy will be removed when the stack is deleted. If set to Retain, the bucket policy will be preserved even after the stack is deleted.

For example, a CloudFormation stack in us-east-1 can use the AWS::S3::BucketPolicy resource to manage the bucket policy for an S3 bucket in us-west-2. The retention or removal of the bucket policy during the stack deletion is determined by the DeletionPolicy attribute specified in the stack template.

For more information, see Bucket policy examples.

The following operations are related to PutBucketPolicy:

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{
  "Type" : "AWS::S3::BucketPolicy",
  "Properties" : {
      "Bucket" : String,
      "PolicyDocument" : Json
    }
}

YAML

Type: AWS::S3::BucketPolicy
Properties:
  Bucket: String
  PolicyDocument: Json

Properties

Bucket

The name of the Amazon S3 bucket to which the policy applies.

Required: Yes

Type: String

Update requires: Replacement

PolicyDocument

A policy document containing permissions to add to the specified bucket. In IAM, you must provide policy documents in JSON format. However, in CloudFormation you can provide the policy in JSON or YAML format because CloudFormation converts YAML to JSON before submitting it to IAM. For more information, see the AWS::IAM::Policy PolicyDocument resource description in this guide and Access Policy Language Overview in the Amazon S3 User Guide.

Required: Yes

Type: Json

Update requires: No interruption

Examples

Bucket policy that allows GET requests from specific referers

The following sample is a bucket policy that is attached to the DOC-EXAMPLE-BUCKET bucket and allows GET requests that originate from www.example.com and example.net:

Important

This key should be used carefully. It is dangerous to include a publicly known referer header value. Unauthorized parties can use modified or custom browsers to provide any aws:referer value that they choose. As a result, aws:referer should not be used to prevent unauthorized parties from making direct AWS requests. It is offered only to allow customers to protect their digital content, such as content stored in Amazon S3, from being referenced on unauthorized third-party sites. For more information, see aws:referer in the IAM User Guide .

JSON

{
    "SampleBucketPolicy": {
        "Type": "AWS::S3::BucketPolicy",
        "Properties": {
            "Bucket": {
                "Ref": "DOC-EXAMPLE-BUCKET"
            },
            "PolicyDocument": {
                "Version": "2012-10-17",
                "Statement": [
                    {
                        "Action": [
                            "s3:GetObject"
                        ],
                        "Effect": "Allow",
                        "Resource": {
                            "Fn::Join": [
                                "",
                                [
                                    "arn:aws:s3:::",
                                    {
                                        "Ref": "DOC-EXAMPLE-BUCKET"
                                    },
                                    "/*"
                                ]
                            ]
                        },
                        "Principal": "*",
                        "Condition": {
                            "StringLike": {
                                "aws:Referer": [
                                    "http://www.example.com/*",
                                    "http://example.net/*"
                                ]
                            }
                        }
                    }
                ]
            }
        }
    }
}

YAML

SampleBucketPolicy:
  Type: AWS::S3::BucketPolicy
  Properties:
    Bucket: !Ref DOC-EXAMPLE-BUCKET
    PolicyDocument:
      Version: 2012-10-17
      Statement:
        - Action:
            - 's3:GetObject'
          Effect: Allow
          Resource: !Join
            - ''
            - - 'arn:aws:s3:::'
              - !Ref DOC-EXAMPLE-BUCKET
              - /*
          Principal: '*'
          Condition:
            StringLike:
              'aws:Referer':
                - 'http://www.example.com/*'
                - 'http://example.net/*'