AWS CDK grant decrypt permission to Kinesis Data Stream's AWS managed CMK-CodePudding

I'm provisioning Kinesis Data Stream with AWS managed KMS key as well as Delivery Stream reading from stream. There's a problem on how to add decrypt policy on delivery stream role for managed key. The code is showing below and the issue is that getting key with 'aws/kinesis' alias doesn't work unless I have a way to add dependency to 'kinesisStream' resource. But there's no 'addDependsOn' method in IKey-interface. How can I ensure that Stream (and it's managed KMS key) is created before I try to fetch that key?

const kinesisStream = new kinesis.Stream(this, 'kinesisStream', {
  streamName: `my-stream`,
  shardCount: 1,
  encryption: kinesis.StreamEncryption.MANAGED,
  retentionPeriod: cdk.Duration.days(1),
});

const kinesisStreamRole = new iam.Role(this, 'kinesisStreamRole', {
  assumedBy: new iam.ServicePrincipal('firehose.amazonaws.com'),
});

// How to add dependency to kinesisStream resource to ensure it's created before trying to fetch KMS key using 'fromLookup'?
// Now getting:
// [Error at /my-stack] Could not find any key with alias named aws/kinesis
const managedKinesisKmsKey = kms.Key.fromLookup(this, 'managedKinesisKmsKey', {
  aliasName: 'aws/kinesis',
});

const managedKinesisKmsKeyPolicy = new iam.Policy(this, 'managedKinesisKmsKeyPolicy', {
    roles: [kinesisStreamRole],
    statements: [
        new iam.PolicyStatement({
            effect: iam.Effect.ALLOW,
            resources: [managedKinesisKmsKey.keyArn],
            actions: ['kms:Decrypt'],
        }),
    ],
});

CodePudding user response：

You can use the key alias to grant the access to this AWS managed key. We know that the alias for Kinesis service specific AWS managed key is "aws/kinesis".

AWS developer guide for using aliases to control access to KMS keys: https://docs.aws.amazon.com/kms/latest/developerguide/alias-authorization.html

CodePudding user response：

Working solution

const kinesisStream = new kinesis.Stream(this, 'kinesisStream', {
    streamName: `my-stream`, 
    shardCount: 1, 
    encryption: kinesis.StreamEncryption.MANAGED, 
    retentionPeriod: cdk.Duration.days(1),
});

const kinesisStreamRole = new iam.Role(this, 'kinesisStreamRole', {
    assumedBy: new iam.ServicePrincipal('firehose.amazonaws.com'),
});

const managedKinesisKmsKeyPolicy = new iam.Policy(this, 'managedKinesisKmsKeyPolicy', {
    roles: [kinesisStreamRole],
    statements: [
        new iam.PolicyStatement({
            effect: iam.Effect.ALLOW,
            resources: ['*'],
            actions: ['kms:Decrypt'],
            conditions: {
                StringLike: {
                    'kms:RequestAlias': 'aws/kinesis',
                },
            },
        }),
    ],
});