Feature Overview (aka. Goal Summary)  

Package-based RHEL workers (non-RHCOS) have been a feature in OpenShift from the start of OpenShift 4. There was a clear need for this support as RHCOS did not support installing additional packages on the base OS as well as some other feature gaps around storage support at install time. Additionally, compliance issues were challenging for some customers. Nonetheless, telemetry suggests RHEL worker usage is low.

While RHEL workers have filled these gaps, they have always been more difficult to test and support as the installation is not highly automated.

Today we support installation of third party agents and other software on the base OS via CoreOS Layering. On Cluster Layering (OCPSTRAT-1389) will add automation and is expected to make the experience of building and maintaining your custom images much simpler. Storage support is being or has been extended to iSCSI/FC multipath, FCoE, RAID, & NVMe options.

The release of Image mode for RHEL should increase the visibility and interest in this approach to system management. Which, in turn, will make it easier for our customers to adopt.

Announcing deprecation in 4.16 means that at a minimum this feature will remain 4.16 through and including 4.18. Removal could come as soon as 4.19.

Goals (aka. expected user outcomes)

Retire package-based RHEL workers and go 100% RHCOS in OpenShift.

Requirements (aka. Acceptance Criteria):

Clusters should not be upgradeable to the target version if there are still package-based workers in the cluster.

Questions to Answer (Optional):

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Out of Scope

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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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