Feature Overview (aka. Goal Summary)  

A common cluster provisioning error that customers currently hit is when the selected subnet CIDR range is outside of the specified machine CIDR range. This is caught by the backend and returned to the user as an error. We should validate that the CIDR range for the subnet falls within the CIDR range for the machine and avoid the user hitting this error during cluster provisioning. This validation should be performed in the UI as well as the CLI.

Goals (aka. expected user outcomes)

The specific error (PreflightMachineCIDRContainsSubnetCIDR) should be eliminated from the list of errors that we track that users hit when they provision clusters.

Requirements (aka. Acceptance Criteria):

The UI wizard (ROSA and OSD) and the CLI should perform CIDR validation and alert the user if the CIDR ranges do not match. Users should not be able to submit a cluster creation request with an invalid machine/subnet CIDR configuration. The validations and restrictions should be aligned with what we have documented in https://docs.openshift.com/rosa/networking/cidr-range-definitions.html

Use Cases (Optional):

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

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.

Out of Scope

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

Background

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

Customer Considerations

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

Documentation Considerations

Provide information that needs to be considered and planned so that documentation will meet customer needs.  Initial completion during Refinement status.

Interoperability Considerations

Which other projects 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.