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Amazon S3 Resources

The following common Amazon Resource Name (ARN) format identifies resources in AWS:

arn:partition:service:region:namespace:relative-id

For information about ARNs, see Amazon Resource Names (ARNs) in the AWS General Reference.

For information about resources, see IAM JSON Policy Elements: Resource in the IAM User Guide.

An Amazon S3 ARN excludes the AWS Region and namespace, but includes the following:

  • Partition ‐ aws is a common partition name. If your resources are in the China (Beijing) Region, aws-cn is the partition name.
  • Service ‐ s3.
  • Relative ID ‐ bucket-name or a bucket-name/object-key. You can use wild cards.

The ARN format for Amazon S3 resources reduces to the following:

1. arn:aws:s3:::bucket_name/key_name

For a complete list of Amazon S3 resources, see Actions, resources, and condition keys for Amazon S3.

To find the ARN for an S3 bucket, you can look at the Amazon S3 console Bucket Policy or CORS configuration permissions pages. For more information, see the following topics in the Amazon Simple Storage Service Console User Guide:

Amazon S3 ARN Examples

The following are examples of Amazon S3 resource ARNs.

Bucket Name and Object Key Specified
The following ARN identifies the /developers/design_info.doc object in the examplebucket bucket.

1. arn:aws:s3:::examplebucket/developers/design_info.doc

Wildcards
You can use wildcards as part of the resource ARN. You can use wildcard characters (* and ?) within any ARN segment (the parts separated by colons). An asterisk (*) represents any combination of zero or more characters, and a question mark (?) represents any single character. You can use multiple * or ? characters in each segment, but a wildcard cannot span segments.

  • The following ARN uses the wildcard * in the relative-ID part of the ARN to identify all objects in the examplebucket bucket.

    1. arn:aws:s3:::examplebucket/*

  • The following ARN uses * to indicate all Amazon S3 resources (all S3 buckets and objects in your account).

    arn:aws:s3:::*

  • The following ARN uses both wildcards, * and ?, in the relative-ID part. It identifies all objects in buckets such as example1bucket, example2bucket, example3bucket, and so on.

    1. arn:aws:s3:::example?bucket/*

Policy Variables
You can use policy variables in Amazon S3 ARNs. At policy evaluation time, these predefined variables are replaced by their corresponding values. Suppose that you organize your bucket as a collection of folders, one folder for each of your users. The folder name is the same as the user name. To grant users permission to their folders, you can specify a policy variable in the resource ARN:

arn:aws:s3:::bucket_name/developers/${aws:username}/

At runtime, when the policy is evaluated, the variable ${aws:username} in the resource ARN is substituted with the user name making the request.