Attach Policy to EventBus using CDK and send cross-account events to Eventbus

Question

What I am trying to do is send an event from a different AWS account to my account which contains the eventbus.

For that I am trying to attach a role/policy to EventBus but I am not able to. I tried to use grantPutEvents but no luck there too. How to do this? (add/attach a Policy)

Also if I attach policy with Principal as account ID of the other AWS account and resource as the ARN of the EventBus, Will this allow me to send events ? Or do I need to do something more?

Supportable

Answer 1

I was able to add a "Resource-based policy" entry by using the base CfnEventBusPolicy class and referencing the corresponding bus by its name:

const defaultBus = event.EventBus.fromEventBusName(this, 'default-bus', 'default');
new event.CfnEventBusPolicy(this, 'xaccount-policy', {
        statementId: 'AllowXAccountPushEvents',
        action: 'events:PutEvents',
        eventBusName: defaultBus.eventBusName,
        principal: 'account-id-goes-here',
});

Screw

I tested exactly the same thing. It works for me with the L1 construct (this reply) but not with defaultBus.grantPutEventsTo. Weird but thanks 👍🏽 – Wavelet

Answer 2

grantPutEventsTo will not work in this scenario, but you can use addToResourcePolicy - no need to use the Cfn constructs:

bus.addToResourcePolicy(
  new iam.PolicyStatement({
    sid: "AllowXAccountPutEvents",
    actions: ["events:PutEvents"],
    resources: [bus.eventBusArn],
    principals: [new iam.AccountPrincipal("xxxxxxxxxxxx")],
  }),
);

This will create an AWS::Events::EventBusPolicy resource in the CloudFormation.

Forsook

Excellent, thank you – Weisshorn

Answer 3

You need:

• sender account: an EventBridge rule for the sender event bus. rule's target is the event bus in the receiver account
• receiver account: update receiver event bus resource-based policy, to allow sender account to put events

this link https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-cross-account.html should help you.

Biphenyl