Resource-based policy examples - Amazon DynamoDB

Resource-based policy examples

When you specify an ARN in the Resource field of a resource-based policy, the policy takes effect only if the specified ARN matches the ARN of the DynamoDB resource to which it is attached.

Note

Remember to replace the italicized text with your resource-specific information.

Resource-based policy for a table

The following resource-based policy attached to a DynamoDB table named MusicCollection, gives the IAM users John and Jane permission to perform GetItem and BatchGetItem actions on the MusicCollection resource.

{ "Version": "2012-10-17", "Statement": [ { "Sid": "1111", "Effect": "Allow", "Principal": { "AWS": [ "arn:aws:iam::111122223333:user/John", "arn:aws:iam::111122223333:user/Jane" ] }, "Action": [ "dynamodb:GetItem", "dynamodb:BatchGetItem" ], "Resource": [ "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection" ] } ] }

Resource-based policy for a stream

The following resource-based policy attached to a DynamoDB stream named 2024-02-12T18:57:26.492 gives the IAM users John and Jane permission to perform GetRecords, GetShardIterator, and DescribeStream API actions on the 2024-02-12T18:57:26.492 resource.

{ "Version": "2012-10-17", "Statement": [ { "Sid": "1111", "Effect": "Allow", "Principal": { "AWS": [ "arn:aws:iam::111122223333:user/John", "arn:aws:iam::111122223333:user/Jane" ] }, "Action": [ "dynamodb:DescribeStream", "dynamodb:GetRecords", "dynamodb:GetShardIterator" ], "Resource": [ "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection/stream/2024-02-12T18:57:26.492" ] } ] }

Resource-based policy for access to perform all actions on specified resources

To allow a user to perform all actions on a table and all associated indexes with a table, you can use a wildcard (*) to represent the actions and the resources associated with the table. Using a wild card character for the resources, will allow the user access to the DynamoDB table and all its associated indexes, including the ones that haven’t yet been created. For example, the following policy will give the user John permission to perform any actions on the MusicCollection table and all of its indexes, including any indexes that will be created in the future.

{ "Version": "2012-10-17", "Statement": [ { "Sid": "1111", "Effect": "Allow", "Principal":"arn:aws:iam::111122223333:user/John", "Action": "dynamodb:*", "Resource": [ "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection", "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection/index/*" ] } ] }

Resource-based policy for cross-account access

You can specify permissions for a cross-account IAM identity to access DynamoDB resources. For example, you might need a user from a trusted account to get access to read the contents of your table, with the condition that they access only specific items and specific attributes in those items. The following policy allows access to user John from a trusted AWS account ID 111111111111 to access data from a table in account 123456789012 by using the GetItem API. The policy ensures that the user can access only items with a primary key Jane and that the user can only retrieve the attributes Artist and SongTitle, but no other attributes.

{ "Version": "2012-10-17", "Statement": [ { "Sid": "CrossAccountTablePolicy", "Effect": "Allow", "Principal": { "AWS": "arn:aws:iam::111111111111:user/John" }, "Action": "dynamodb:GetItem", "Resource": [ "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection" ], "Condition": { "ForAllValues:StringEquals": { "dynamodb:LeadingKeys": "Jane", "dynamodb:Attributes": [ "Artist", "SongTitle" ] } } } ] }

In addition to the preceding resource-based policy, the identity-based policy attached to the user John also needs to allow the GetItem API action for the cross-account access to work. The following is an example of an identity-based policy that you must attach to the user John.

{ "Version": "2012-10-17", "Statement": [ { "Sid": "CrossAccountIdentityBasedPolicy", "Effect": "Allow", "Action": [ "dynamodb:GetItem" ], "Resource": [ "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection" ], "Condition": { "ForAllValues:StringEquals": { "dynamodb:LeadingKeys": "Jane", "dynamodb:Attributes": [ "Artist", "SongTitle" ] } } } ] }

The user John can make a GetItem request by specifying the table ARN in the table-name parameter for accessing the table MusicCollection in the account 123456789012.

aws dynamodb get-item \ --table-name arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection \ --key '{"Artist": {"S": "Jane"},"bash": {"SongTitle": "Monsoon"}}' \ --return-consumed-capacity TOTAL

Resource-based policy with IP address conditions

You can apply a condition to restrict source IP addresses, virtual private clouds (VPCs), and VPC endpoint (VPCE). You can specify permissions based on the source addresses of the originating request. For example, you might want to allow a user to access DynamoDB resources only if they are being accessed from a specific IP source, such as a corporate VPN endpoint. Specify these IP addresses in the Condition statement.

The following example allows the user John access to any DynamoDB resource when the source IPs are 54.240.143.0/24 and 2001:DB8:1234:5678::/64.

{ "Id":"PolicyId2", "Version":"2012-10-17", "Statement":[ { "Sid":"AllowIPmix", "Effect":"Allow", "Principal":"arn:aws:iam::111111111111:user/John", "Action":"dynamodb:*", "Resource":"*", "Condition": { "IpAddress": { "aws:SourceIp": [ "54.240.143.0/24", "2001:DB8:1234:5678::/64" ] } } } ] }

You can also deny all access to DynamoDB resources except when the source is a specific VPC endpoint, for example vpce-1a2b3c4d.

{ "Id":"PolicyId", "Version":"2012-10-17", "Statement": [ { "Sid": "AccessToSpecificVPCEOnly", "Principal": "*", "Action": "dynamodb:*", "Effect": "Deny", "Resource": "*", "Condition": { "StringNotEquals":{ "aws:sourceVpce":"vpce-1a2b3c4d" } } } ] }

Resource-based policy using an IAM role

You can also specify an IAM service role in the resource-based policy. IAM entities that assume this role are bounded by the permissible actions specified for the role and to the specific set of resources within the resource-based policy.

The following example allows an IAM entity to perform all DynamoDB actions on the MusicCollection and MusicCollection DynamoDB resources.

{ "Version": "2012-10-17", "Statement": [ { "Sid": "1111", "Effect": "Allow", "Principal": { "AWS": "arn:aws:iam::111122223333:role/John" }, "Action": "dynamodb:*", "Resource": [ "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection", "arn:aws:dynamodb:us-west-2:123456789012:table/MusicCollection/*" ] } ] }