Configuring cross-account access to Amazon Keyspaces without a shared VPC - Amazon Keyspaces (for Apache Cassandra)
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Configuring cross-account access to Amazon Keyspaces without a shared VPC

If the Amazon Keyspaces table and private VPC endpoint are owned by different accounts but are not sharing a VPC, applications can still connect cross-account using VPC endpoints. Because the accounts are not sharing the VPC endpoints, Account A:111111111111, Account B:222222222222, and Account C:333333333333 require their own VPC endpoints. To the Cassandra client driver, Amazon Keyspaces appears like a single node instead of a multi-node cluster. Upon connection, the client driver reaches the DNS server which returns one of the available endpoints in the account’s VPC.

You can also access Amazon Keyspaces tables across different accounts without a shared VPC endpoint by using the public endpoints or deploying a private VPC endpoint in each account. When not using a shared VPC, each account requires its own VPC endpoint. In this example Account A:111111111111, Account B:222222222222, and Account C:333333333333 require their own VPC endpoints to access the table in Account A:111111111111. When using VPC endpoints in this configuration, Amazon Keyspaces appears as a single node cluster to the Cassandra client driver instead of a multi-node cluster. Upon connection, the client driver reaches the DNS server which returns one of the available endpoints in the account’s VPC. But the client driver is not able to access the system.peers table to discover additional endpoints. Because there are less hosts available, the driver makes less connections. To adjust this, increase the connection pool setting of the driver by a factor of three.

Diagram showing three different accounts in owned by the same organization in the same Amazon Web Services Region without a shared VPC.

Account A:111111111111 is the account that contains the resources (an Amazon Keyspaces table) that Account B:222222222222 and Account C:333333333333 need to access, so Account A:111111111111 is the trusting account. Account B:222222222222 and Account C:333333333333 are the accounts with the principals that need access to the resources (an Amazon Keyspaces table) in Account A:111111111111, so Account B:222222222222 and Account C:333333333333 are the trusted accounts. The trusting account grants the permissions to the trusted accounts by sharing an IAM role. The following procedure outlines the configuration steps required in Account A:111111111111.

Configuration for Account A:111111111111

  1. Create an Amazon Keyspaces keyspace and table in Account A:111111111111.

  2. Create an IAM role in Account A:111111111111 that has full access to the Amazon Keyspaces table and read access to the Amazon Keyspaces system tables.

    {
   "Version":"2012-10-17",
   "Statement":[
      {
         "Effect":"Allow",
         "Action":[
            "cassandra:Select",
            "cassandra:Modify"
         ],
         "Resource":[
            "arn:aws-cn:cassandra:us-east-1:111111111111:/keyspace/mykeyspace/table/mytable",
            "arn:aws-cn:cassandra:us-east-1:111111111111:/keyspace/system*"
         ]
      }
   ]
}

  3. Configure a trust policy for the IAM role in Account A:111111111111 so that principals in Account B:222222222222 and Account C:333333333333 can assume the role as trusted accounts. This is shown in the following example. 

    {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": [
          "arn:aws-cn:iam::222222222222:role/Cross-Account-Role-B",
          "arn:aws-cn:iam::333333333333:role/Cross-Account-Role-C"
        ]
      },
      "Action": "sts:AssumeRole",
      "Condition": {}
    }
  ]
}

    For more information about cross-account IAM policies, see Cross-account policies in the IAM User Guide.

  4. Configure the VPC endpoint in Account A:111111111111 and attach permissions to the endpoint that allow the roles from Account B:222222222222 and Account C:333333333333 to assume the role in Account A using the VPC endpoint. These permissions are valid for the VPC endpoint that they are attached to. For more information about VPC endpoint policies, see Controlling access to interface VPC endpoints for Amazon Keyspaces.

    {{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowAccessfromSpecificIAMroles",
      "Effect": "Allow",
      "Action": "cassandra:*",
      "Resource": "*",
      "Principal": "*",
      "Condition": {
        "ArnEquals": {
          "aws:PrincipalArn": [
            "arn:aws-cn:iam::222222222222:role/Cross-Account-Role-B",
            "arn:aws-cn:iam::333333333333:role/Cross-Account-Role-C"
          ]
        }
      }
    }
  ]
}
Configuration in Account B:222222222222 and Account C:333333333333

  1. In Account B:222222222222 and Account C:333333333333, create new roles and attach the following policy that allows the principal to assume the shared role created in Account A:111111111111.

    {
    "Version": "2012-10-17",
    "Statement": {
            "Effect": "Allow",
            "Action": "sts:AssumeRole",
            "Resource": "arn:aws-cn:iam::111111111111:role/keyspaces_access"
        }
}

    Allowing the principal to assume the shared role is implemented using the AssumeRole API of the Amazon Security Token Service (Amazon STS). For more information, see Providing access to an IAM user in another Amazon Web Services account that you own in the IAM User Guide.

  2. In Account B:222222222222 and Account C:333333333333, you can create applications that utilize the SIGV4 authentication plugin, which allows an application to assume the shared role to connect to the Amazon Keyspaces table located in Account A:111111111111. For more information about the SIGV4 authentication plugin, see Create credentials for programmatic access to Amazon Keyspaces . For more information on how to configure an application to assume a role in another Amazon account, see Authentication and access in the Amazon SDKs and Tools Reference Guide.