Feature Overview (aka. Goal Summary)  

We need a way to generically ensure HostedCluster placement rules are placed on all the HCP components without baking in knowledge of the HostedCluster into multiple operators. 

Below is a more detailed explanation of why this is important.

The HostedCluster influences the placement of where the control plane component pods are scheduled within the management cluster. Since most components are deployed directly by the CPO (a hypershift component), it is fairly simple to inject the HostedCluster placement rules into those components.

However, there are other opreators (like the cluster-storage-operator) which influence the placement of additional components within the control plane's namespace that are not directly laid down by the CPO. This means the knowledge of the placement rules that the HostedCluster defines have to propagate to components beyond the components owned by the hypershift repo. 

The result has been error prone. When changes happen to the HostedCluster scheduling, sometimes those changes don't accurately propagate to other components because the knowledge of what components are impacted by the change to the hypershift repo are not obvious.

For example, when the Tolerations feature was added to the HostedCluster, it wasn't obvious that the change impacted multiple other repos, such as the network operator, storage operator, csi operators, etc... Today, all of those operators independently have to inspect the HostedCluster object and understand how to interpret the HostedCluster object. This has lead to inconsistent results

Goals (aka. expected user outcomes)

Introduce a generic way of influencing the placement of HCP components that does not require components outside of the Hypershift repo to interpret the HostedCluster object directly. 

Requirements (aka. Acceptance Criteria):

A list of specific needs or objectives that a feature must deliver in order to be considered complete.  Be sure to include nonfunctional requirements such as security, reliability, performance, maintainability, scalability, usability, etc.  Initial completion during Refinement status.

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Anyone reviewing this Feature needs to know which deployment configurations that the Feature will apply to (or not) once it's been completed.  Describe specific needs (or indicate N/A) for each of the following deployment scenarios. For specific configurations that are out-of-scope for a given release, ensure you provide the OCPSTRAT (for the future to be supported configuration) as well.

Use Cases (Optional):

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Questions to Answer (Optional):

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Out of Scope

High-level list of items that are out of scope.  Initial completion during Refinement status.

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Background

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Customer Considerations

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Documentation Considerations

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Interoperability Considerations

Which other projects, including ROSA/OSD/ARO, and versions in our portfolio does this feature impact?  What interoperability test scenarios should be factored by the layered products?  Initial completion during Refinement status.

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