Feature Overview (aka. Goal Summary)  

An elevator pitch (value statement) that describes the Feature in a clear, concise way.  Complete during New status.

As a cluster Administrator I want to introduce change management in Standalone OCP to allow separation of Control Plane and Worker, permitting administrators to have fine grained control of when pending changes are applied to each by introducing the concept of change management. Change management will allow multiple flexible options in managing update disruptions, but the expected use will allow admins to define recurring maintenance schedules to control the initiation and progress of updates.

Goals (aka. expected user outcomes)

The observable functionality that the user now has as a result of receiving this feature. Include the anticipated primary user type/persona and which existing features, if any, will be expanded. Complete during New status.

• Admins can define a maintenance schedule to protect sensitive workloads from rolling restarts outside of selected times during which workload disruptions are permitted. 
• Admins can also exclude certain dates from potentially disruptive updates. These are common expectations for enterprise grade systems. 
• Admins can define a timebound one-off exception to immediately apply changes.
• Admins can disable a maintenance schedule halting additional changes depending on the change granularity offered by various controllers.
• Admins can monitor change management via "oc adm update status" command.
• Admins can use home grown tools to customize update roll-outs when a recurring maintenance schedule is not appropriate for their use case.

The feature also provides fine grained manual control over when updates are deployed when maintenance schedules do not fulfill their requirements.

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.

• https://github.com/openshift/enhancements/pull/1571 is accepted and merge
• A new ChangeManagementPolicy CRD is defined for change management
• A controller is written which keeps the status of ChangeManagementPolicy resources up to date based on permissive state

• Change Management Strategies

• Maintenance Schedule Strategy

• Restrictive Strategy

• Permissive Strategy

• ClusterVersion adds field for ChangeManagementPolicy resource and Cluster Version Operator observes its status to know when changes may be initiated
• MachineConfigPools add a field for ChangeManagementPolicy resource and MCO/MCC observes its status to know when changes may be initiated
• status command to show changemanagement in progress.

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):

Include use case diagrams, main success scenarios, alternative flow scenarios.  Initial completion during Refinement status.

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GitOps based management of cluster configuration is simplified by ensuring that git based changes are rolled out during permitted windows.

Questions to Answer (Optional):

Include a list of refinement / architectural questions that may need to be answered before coding can begin.  Initial completion during Refinement status.

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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

Provide any additional context is needed to frame the feature.  Initial completion during Refinement status.

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Customer Considerations

Provide any additional customer-specific considerations that must be made when designing and delivering the Feature.  Initial completion during Refinement status.

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Documentation Considerations

Provide information that needs to be considered and planned so that documentation will meet customer needs.  If the feature extends existing functionality, provide a link to its current documentation. Initial completion during Refinement status.

<your text here>

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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