Add validation to require at least one RabbitMQ instance

[lmiccini]

This commit adds webhook validation to ensure that when RabbitMQ is enabled (spec.rabbitmq.enabled: true), at least one RabbitMQ instance must be defined in spec.rabbitmq.templates.

Previously, the validation only checked the boolean flag (spec.rabbitmq.enabled) without verifying that actual RabbitMQ instances were configured. This allowed invalid configurations where services requiring RabbitMQ could pass validation but would fail at runtime when trying to create TransportURLs to non-existent clusters.

Changes:

• ValidateCreateServices: Reject creation when rabbitmq.enabled is true but templates is nil or empty
• ValidateUpdateServices: Reject updates that remove all instances while RabbitMQ remains enabled
• Allow disabling RabbitMQ and removing all instances in the same update operation
• Add 7 comprehensive test cases covering CREATE and UPDATE scenarios

The validation provides a clear error message:
"At least one RabbitMQ instance must be defined when rabbitmq is enabled"

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: lmiccini
Once this PR has been reviewed and has the lgtm label, please assign rebtoor for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[lmiccini]

/test functional

[github-actions]

OpenStackControlPlane CRD Size Report

Metric	Value
CRD JSON size	322326 bytes (315KB)
Base branch size	322326 bytes
Change	+0.00%
Status	yellow — growing

Threshold reference

Color	Range	Meaning
🟢 green	< 300KB	Comfortable
🟡 yellow	300–400KB	Growing
🟠 orange	400–750KB	Concerning
🔴 red	> 750KB	Approaching 1.5MB etcd limit (cut in half to allow space for update)

[softwarefactory-project-zuul]

Build failed (check pipeline). Post recheck (without leading slash)
to rerun all jobs. Make sure the failure cause has been resolved before
you rerun jobs.

https://softwarefactory-project.io/zuul/t/rdoproject.org/buildset/ae0bd4b8523d41ad90f6cf9915555322

❌ openstack-k8s-operators-content-provider FAILURE in 3m 59s
⚠️ podified-multinode-edpm-deployment-crc SKIPPED Skipped due to failed job openstack-k8s-operators-content-provider
⚠️ cifmw-crc-podified-edpm-baremetal SKIPPED Skipped due to failed job openstack-k8s-operators-content-provider
⚠️ openstack-operator-tempest-multinode SKIPPED Skipped due to failed job openstack-k8s-operators-content-provider
⚠️ openstack-operator-edpm-baremetal-minor-update SKIPPED Skipped due to failed job openstack-k8s-operators-content-provider

[openshift-ci]

@lmiccini: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/openstack-operator-build-deploy-kuttl-4-20	cc45b15	link	true	/test openstack-operator-build-deploy-kuttl-4-20

Full PR test history. Your PR dashboard.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.