Background & Overview

Currently, MCE ships with specific HO/CLI versions that are tested and supported for a limited set of OCP versions. This requires backporting fixes and features to older MCE versions, which is time-consuming and inefficient. Additionally, it makes supported older OCP versions which are still in support due to the OpenShift lifecycle hard. 

The idea is to simplify the HyperShift Operator and CLI release process by shipping them directly from the main branch in all versions of MCE. This eliminates the need for backports and streamlines testing, enabling faster delivery of new features and bug fixes to MCE users.

Goals

• Simplified Testing Matrix: Reduce the HO/CLI test matrix by focusing on the main branch, eliminating the need for version-specific testing.
• Faster Feature Delivery: Enable quicker delivery of new HO/CLI features and bug fixes to MCE users.
• Reduced Maintenance Overhead: Eliminate the effort required for HO/CLI backports to older MCE versions.
• Improved User Experience: Provide MCE users with the latest HO/CLI capabilities across all supported OCP versions.

Requirements

• The HO/CLI from the main branch must be compatible with all supported OCP versions within the MCE lifecycle.
• API compatibility must be maintained to avoid breaking changes for existing MCE/HCP users.
• Comprehensive testing must be conducted to ensure the stability and reliability of the HO/CLI from main across all supported OCP versions.
• Documentation must be updated to reflect the change in HO/CLI release process.

Deployment Considerations:

Use Cases

• Simplified MCE Upgrades: Users can upgrade to newer MCE versions without worrying about HO/CLI compatibility issues.
• Faster Access to New Features: Users can leverage the latest HO/CLI features across all supported OCP versions (might be a curse for some customers though, which is why APIs need to be solid)
• Reduced Support Burden: Simplified testing and release process reduces the likelihood of bugs and support requests.

Questions to Answer

• How will API compatibility be guaranteed when shipping HO/CLI from main? Besides the sustainability effort, what else do we need? 
• What are the testing requirements to ensure compatibility across all supported OCP versions?
• How will documentation be updated to reflect the change?
• What are the potential security implications of shipping HO/CLI from main?
• How do we stay true to the OpenShift Lifecycle: https://access.redhat.com/support/policy/updates/openshift
• Take into consideration timespans for EUS and EUS plus.

Out of Scope

• Support for unsupported OCP versions.
• Significant changes to the HO/CLI architecture or functionality.

Customer Considerations

Customers may have concerns about API stability and compatibility when shipping HO/CLI from main. Clear communication and documentation are essential to address these concerns.

Documentation Considerations

The MCE/HCP documentation must be updated to reflect the change in HO/CLI release process and clearly outline the supported OCP versions.

Complimentary Efforts 

• https://github.com/openshift/openshift-docs/pull/82541 
• https://github.com/stolostron/hypershift-addon-operator/blob/main/docs/supported_versions.md