AWS EventBridge bus resource policy

[bobthemighty]

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Description

AWS have added support for resource policies that allow more granular control over who can subscribe or publish to a bus.

They've chosen to expose this behaviour by extending the existing PutPermission action on the eventbridge resource. This API endpoint now accepts either a policy document (the new behaviour), or an action, statement, principal and condition that AWS will merge with the existing resource policy (previous behaviour). Each permission resource effectively becomes a new statement on the policy.

The aws_cloudwatch_event_permission resource is quite constrained, and supports the second, older behaviour. When loading state, the resource parses the policy document and matches statement IDs to figure out which permission resources are present. I'm unable to use this resource as is, because it doesn't support the actions or condition keys that I want to use, but which are supported by the policy language.

If I create the policy manually on my event bus, Terraform is unable to load the bus as a permission resource because it doesn't recognise the actions I've added.

I would like to submit a new aws_cloudwatch_event_bus_policy resource that allows control of the resource policy document directly. This would not be compatible with the existing permission resource. Policies created directly in EventBridge might not be readable as aws_cloudwatch_event_permission resources. I suspect that having direct access to the resource policy means that the aws_cloudwatch_event_permission resource can be fully deprecated.

New or Affected Resource(s)

• New: aws_cloudwatch_event_bus_policy
• Replace: aws_cloudwatch_event_permission

Potential Terraform Configuration

resource "aws_cloudwatch_event_bus_policy" "test" {
   event_bus_name = "my-excellent-event-bus"
   policy = some_policy_document.json
}

References

• Resource policy announcement for EventBridge
• Syntax for the PutPermission call which supports either a policy or the components of a statement.

[github-actions]

This functionality has been released in v3.47.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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