Add eventbus to cloudwatch event rule

[gdavison]

Completes work from #12886 to add custom event buses to CloudWatch Events rules.

Closes #12886
Relates #9330

Release note for CHANGELOG:

* resource/aws_cloudwatch_event_rule: Add `event_bus_name`

Output from acceptance testing:

$ make testacc TESTARGS='-run=TestAccAWSCloudWatchEventRule_'

--- PASS: TestAccAWSCloudWatchEventRule_Name_Generated (119.30s)
--- PASS: TestAccAWSCloudWatchEventRule_NamePrefix (124.29s)
--- PASS: TestAccAWSCloudWatchEventRule_ScheduleAndPattern (124.30s)
--- PASS: TestAccAWSCloudWatchEventRule_role (130.35s)
--- PASS: TestAccAWSCloudWatchEventRule_description (165.74s)
--- PASS: TestAccAWSCloudWatchEventRule_pattern (167.54s)
--- PASS: TestAccAWSCloudWatchEventRule_IsEnabled (198.77s)
--- PASS: TestAccAWSCloudWatchEventRule_basic (198.91s)
--- PASS: TestAccAWSCloudWatchEventRule_EventBusName (201.43s)
--- PASS: TestAccAWSCloudWatchEventRule_tags (223.86s)

[awendt]

@gdavison Thanks for working on this. We created a fork based on 3.12.0, merged in your changes from this PR (and resource_aws_cloudwatch_event_target) but noticed we cannot import rules that are defined on an event bus different from default. Here's a minimal config:

provider "aws" {
  version = "3.12.0-with-15727-and-15799"

  region = "eu-west-1"
}

data "aws_caller_identity" "current" {}

resource "aws_cloudwatch_event_bus" "test" {
  name = "test-awendt"
}

resource "aws_cloudwatch_event_rule" "non-default-bus" {
  event_bus_name = aws_cloudwatch_event_bus.test.name

  description    = "Filters all events from EventBridge Bus ${aws_cloudwatch_event_bus.test.name}"
  is_enabled     = false
  name           = "test-rule"
  event_pattern  = jsonencode(
    {
      account = [
        data.aws_caller_identity.current.account_id,
      ]
    }
  )
}

Steps to reproduce

1. Create the event bus using AWS CLI: aws events create-event-bus --name test-awendt
2. Create an event rule on that bus: aws events put-rule --name test-rule --state DISABLED --event-pattern "{\"account\": [\"AWS_ACCOUNT_ID\"]}" --event-bus-name test-awendt (you need to interpolate the account ID)
3. Import the event bus: terraform import aws_cloudwatch_event_bus.test test-awendt
4. Import the event rule: terraform import aws_cloudwatch_event_rule.non-default-bus test-rule

This last step fails with:

aws_cloudwatch_event_rule.non-default-bus: Importing from ID "test-rule"...
aws_cloudwatch_event_rule.non-default-bus: Import prepared!
  Prepared aws_cloudwatch_event_rule for import
aws_cloudwatch_event_rule.non-default-bus: Refreshing state... [id=test-rule]

Error: Cannot import non-existent remote object

While attempting to import an existing object to
aws_cloudwatch_event_rule.non-default-bus, the provider detected that no
object exists with the given id. Only pre-existing objects can be imported;
check that the id is correct and that it is associated with the provider's
configured region or endpoint, or use "terraform apply" to create a new remote
object for this resource.

Can you reproduce this? What could be causing this behavior?

[awendt]

@gdavison Some more context: We noticed Terraform wanted to create a resource that was already existing. It seems both refresh and import are not working as intended.

[gdavison]

Hi @awendt. When importing a rule for a non-default bus, the format of the import id is /, and it assumes that the bus is the default bus if only the is passed. In the example you posted, you'd need to call terraform import aws_cloudwatch_event_rule.non-default-bus test-awendt/test-rule.

[bflad]

One small question, otherwise LGTM 🚀

Output from acceptance testing:

--- PASS: TestAccAWSCloudWatchEventRule_ScheduleAndPattern (34.58s)
--- PASS: TestAccAWSCloudWatchEventRule_Name_Generated (38.15s)
--- PASS: TestAccAWSCloudWatchEventRule_NamePrefix (39.13s)
--- PASS: TestAccAWSCloudWatchEventRule_role (53.03s)
--- PASS: TestAccAWSCloudWatchEventRule_pattern (56.78s)
--- PASS: TestAccAWSCloudWatchEventRule_description (58.19s)
--- PASS: TestAccAWSCloudWatchEventRule_IsEnabled (68.64s)
--- PASS: TestAccAWSCloudWatchEventRule_basic (71.60s)
--- PASS: TestAccAWSCloudWatchEventRule_EventBusName (72.20s)
--- PASS: TestAccAWSCloudWatchEventRule_tags (82.68s)

[bflad]

Nit: Is the API error not clear in this case?

[gdavison]

This is short-circuiting the API call. I would have set it as a ValidateFunc if they supported cross-attribute validation

[awendt]

@gdavison Thanks for catching this, I can confirm the import works as you described. 🎉

I was also able to track down the root cause why refresh isn't working for us, and I believe we can just re-import the resources and all will be good.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!