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  1. OpenShift Container Platform (OCP) Strategy
  2. OCPSTRAT-1194

MCO: move to Layered update path by default



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      Feature Overview (aka. Goal Summary)  

      Today RHEL CoreOS is a combination of a standard read-only base image and cluster configuration that is applied by the Machine Config Daemon (MCD) locally on each node.

      On-cluster Layering introduces a new configuration flow where the rendered machineconfig is applied during the container image build process.

      Initially this flow only applies to situations where there is customization through a layered pool but this feature proposes to move to the build process as the standard flow for all scenarios.

      The MCD is difficult to test and problems can be difficult to root cause as many tests can't be done outside of a working cluster. It also relies on OS functionality that is constantly being updated.

      Moving to a daemonless architecture would would greatly improve reliability of applying machineconfig content and eliminate entire classes of bugs. It is also expected to improve troubleshooting.

      Goals (aka. expected user outcomes)

      This should be mostly transparent to users.

      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.

      <enter general Feature acceptance here>


      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.

      Deployment considerations List applicable specific needs (N/A = not applicable)
      Self-managed, managed, or both  
      Classic (standalone cluster)  
      Hosted control planes  
      Multi node, Compact (three node), or Single node (SNO), or all  
      Connected / Restricted Network  
      Architectures, e.g. x86_x64, ARM (aarch64), IBM Power (ppc64le), and IBM Z (s390x)  
      Operator compatibility  
      Backport needed (list applicable versions)  
      UI need (e.g. OpenShift Console, dynamic plugin, OCM)  
      Other (please specify)  

      Use Cases (Optional):

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

      <your text here>

      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.

      <your text here>

      Out of Scope

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

      <your text here>


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

      <your text here>

      Customer Considerations

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

      <your text here>

      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.

      <your text here>




            rhn-support-mrussell Mark Russell
            rhn-support-mrussell Mark Russell
            Matthew Werner Matthew Werner
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