Feature Overview

To continue to support RHACM scaling requirements. This issue tracks the integration of Maestro into the ACM Hub and Klusterlet via a feature flag. By leveraging Maestro’s relational database backend and CloudEvents-based messaging, we hope to offer a way for ACM admins to reduce Hub resource consumption, improve the status feedback loop, and scale beyond current architectural limits without linear infrastructure growth. 

Maestro enhances security by leveraging a message broker for resource delivery, reducing the need for direct Hub-to-Managed cluster Kube-API access and eliminating the storage of sensitive kubeconfigs for the transport layer.

Maestro is currently available as an add-on and this feature deprecates that functionality.

Full details are here: https://docs.google.com/document/d/1YOJoC7VORRLHo-w-GCkUSgwEhITkGOPRPc7mCVVmoJo/edit?tab=t.0

Goals

• Make MCE the primary location for Maestro in ACM so you don't have to add it as an add-on. 
• Allow an admin to enable Maestro with different protocols via a feature flag.
• Bring gRPC capabilities into ACM (default)
• Work agent can be able to subscribe to CloudEvents, applies resources to the local cluster, and reports status back to the Maestro Server
• Enable the ability to offload "Work" to a database and a lightweight gRPC/REST server, so the the Hub cluster can remain relatively small even as the managed fleet grows.
• Move resource storage to a relational database (PostgreSQL) allowing the Hub to handle hundreds of thousands of "Work" items without impacting the core Kubernetes control plane.

Requirements

This Section: A list of specific needs or objectives that a Feature must
deliver to satisfy the Feature.. Some requirements will be flagged as MVP.
If an MVP gets shifted, the feature shifts. If a non MVP requirement slips,
it does not shift the feature.

(Optional) Use Cases

This Section:

Questions to answer

• ...

Out of Scope

• …

Background, and strategic fit

This Section: What does the person writing code, testing, documenting
need to know? What context can be provided to frame this feature?

Assumptions

• ...

Customer Considerations

• ...

Documentation Considerations

Questions to be addressed:

• What educational or reference material (docs) is required to support this
  product feature? For users/admins? Other functions (security officers, etc)?
• Does this feature have a doc impact?
• New Content, Updates to existing content, Release Note, or No Doc Impact
• If unsure and no Technical Writer is available, please contact Content
  Strategy.
• What concepts do customers need to understand to be successful in
  [action]?
• How do we expect customers will use the feature? For what purpose(s)?
• What reference material might a customer want/need to complete [action]?
• Is there source material that can be used as reference for the Technical
  Writer in writing the content? If yes, please link if available.
• What is the doc impact (New Content, Updates to existing content, or
  Release Note)?