r/aws_cloudwatch_event_rule, aws_cloudwatch_event_target: Suppress equivalent 'event_bus_name' name/ARN diff

[automationforthepeople]

Rollback Plan

If a change needs to be reverted, we will publish an updated version of the library.

Changes to Security Controls

No changes to security controls.

Description

aws_cloudwatch_event_rule and aws_cloudwatch_event_target accept either a bus name or ARN for event_bus_name, but the current implementation forces resource replacement when switching between the two forms — even though they reference the same physical event bus.

When create_before_destroy is active, the replacement cycle causes data loss: the EventBridge API's upsert semantics (PutRule/PutTargets) mean the "create" and "delete" operations target the same physical resource, so the net result is deletion.

This change adds a DiffSuppressFunc that extracts the bus name from an ARN before comparison, suppressing the false-positive diff. Follows the same pattern as vpclattice (suppressEquivalentIDOrARN, PR #32658).

AI Disclosure: AI assisted with identifying the root cause, researching precedent patterns in the codebase, and generating the initial implementation. The human author reviewed all code, verified test coverage, and understands the change fully.

Relations

Closes #48985

References

• PR #32658 — identical pattern for vpclattice service network identifier
• PR #30109 — relaxed validation to accept ARNs but did not add diff suppression
• EventBridge PutRule API — EventBusName accepts name or ARN

Output from Acceptance Testing

% go test ./internal/service/events/... -run "TestSuppressEquivalentBusNameOrARN|TestBusNameFromNameOrARN" -v

--- PASS: TestBusNameFromNameOrARN (0.00s)
    --- PASS: TestBusNameFromNameOrARN/my-bus (0.00s)
    --- PASS: TestBusNameFromNameOrARN/arn:aws:events:us-east-1:123456789012:event-bus/default (0.00s)
    --- PASS: TestBusNameFromNameOrARN/arn:aws:events:us-east-1:123456789012:event-bus/my-bus (0.00s)
    --- PASS: TestBusNameFromNameOrARN/default (0.00s)
    --- PASS: TestBusNameFromNameOrARN/arn:aws-us-gov:events:us-gov-west-1:123456789012:event-bus/custom_bus-123 (0.00s)
--- PASS: TestSuppressEquivalentBusNameOrARN (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/same_name (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/govcloud_ARN_to_name (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/default_bus_name_vs_default_ARN (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/different_bus_names (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/name_to_equivalent_ARN (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/same_ARN (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/ARN_to_equivalent_name (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/name_vs_different_ARN (0.00s)
    --- PASS: TestSuppressEquivalentBusNameOrARN/ARNs_in_different_regions_same_bus_name (0.00s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/events	0.112s

Note: We do not have access to run full acceptance tests (make testacc) against live AWS infrastructure. The unit tests verify the suppress logic. Existing acceptance tests TestAccEventsRule_eventBusARN and TestAccEventsTarget_eventBusARN exercise the ARN code path and should continue to pass unchanged.

[github-actions]

Community Guidelines

This comment is added to every new Pull Request to provide quick reference to how the Terraform AWS Provider is maintained. Please review the information below, and thank you for contributing to the community that keeps the provider thriving! 🚀

Voting for Prioritization

• Please vote on this Pull Request by adding a 👍 reaction to the original post to help the community and maintainers prioritize it.
• Please see our prioritization guide for additional information on how the maintainers handle prioritization.
• Please do not leave +1 or other comments that do not add relevant new information or questions; they generate extra noise for others following the Pull Request and do not help prioritize the request.

Pull Request Authors

• Review the contribution guide relating to the type of change you are making to ensure all of the necessary steps have been taken.
• Whether or not the branch has been rebased will not impact prioritization, but doing so is always a welcome surprise.