Feature Overview (aka. Goal Summary)  

OCP 4.21 will tech preview  optional support  RHEL10 (dual stream). MicroShift needs to support that, too.

Starting from this release, MicroShift has to support both RHEL9.x and RHEL10.x

Goals (aka. expected user outcomes)

Requirements (aka. Acceptance Criteria):

1. Support MicroShift on RHEL10 X86 and ARM
2. Older MicroShift versions will remain unchanged in their support policy
3. Support upgrade from supported previous combinations to current one. Exact combinations to be decided
4. Only a direct and simultaneous upgrade of BOTH  MicroShift and RHEL is supported. This needs to be especially highlighted in the upgrade documentation, because there is a danger on rpm based systems to just do a `dnf update`, which would give you an upgrade on  RHEL bot NOT MicroShift, as this requires to manually change to the OCP rpm repos.
5. If technically possible, it would be good to protect users against this, e.g. by adding suitable dependency to MicroShift rpms that would block an update to a newer RHEL. 

Out of Scope

• Support for older RHEL versions
• Stepwise upgrade. E.g. upgrade first to 4.16 on RHEL 9.2, then upgrade to RHEL 9.4. The first step would result in an unsupported config (4.16 on RHEL 9.2) and is not supported.

Background

MicroShift & RHEL Combinations Support Policy Considerations

Customer Considerations

Documentation Considerations

Release compatibility matrix and installation instructions need to be updated.

Interoperability Considerations

• none

Open Questions

• Which upgrade combinations are going to be supported? Is it e.g. from V4.18/9.4 (EUS Combo) to V4.19/10.x allowed and possible?