consumer

pkg/messaging/consumer

Intention

pkg/messaging/consumer contains reusable consumers for the pkg/messaging contract. Today that mostly means one thing: deletion-driven local fan-out.

The package is not a broad library of message-processing patterns. It is a narrow home for consumers that can be reused across services when lifecycle events need to trigger predictable follow-up work.

What Lives Here

• CascadingDelete, a consumer that:
  • ignores live events
  • reacts to deletion events
  • lists local resources, optionally filtered by a resource-ID label
  • issues foreground deletes so downstream cleanup can complete before the referenced object is finally removed

Relationships

• pkg/messaging defines the envelope, replay, and retry contract.
• pkg/messaging/kubernetes is the current backend that delivers those envelopes.
• pkg/manager and the broader finalizer/reference model are the reason this consumer exists: deletion of one resource often has to fan out before another resource may finish disappearing.

Invariants

• CascadingDelete treats deletion as the only actionable event. A nil deletion timestamp is intentionally ignored.
• If WithResourceLabel() is used, the consumer assumes that label identifies the local resources owned by or referencing the deleted upstream resource.
• Foreground deletion is used on purpose so owner-reference and finalizer-driven cleanup blocks until dependents are actually cleared.

Caveats

• This is a sharp tool. If the resource label is wrong or omitted carelessly, the consumer can delete far more than intended.
• The consumer is only thinly generic. It relies on the local resource type being listable via client.ObjectList and on the system of record being Kubernetes.
• The package currently has one real consumer. If more appear, they should earn their place by being genuinely reusable rather than just being nearby.