Skip attach for non-attachable CSI volumes

Table of Contents

• Summary
• Test Plan
• Graduation Criteria
  • Alpha -> Beta
  • Beta -> GA
• Implementation History

Summary

This document presents a design to be able to skip the attach/detach flow in Kubernetes for CSI plugins that don’t support attaching.

The detailed design was originally implemented as a design proposal .

This KEP contains details that are missing from the design proposal.

Test Plan

• Unit tests in attach detach controller
• Integration tests:
  • A VolumeAttachment object is not created for CSI drivers that don’t support attach
  • A VolumeAttachment object is created for CSI drivers that do support attach
  • A VolumeAttachment object is created for CSI drivers that did not specify attach support
• E2E tests:
  • Drivers that don’t support attach don’t need the external-attacher and can mount volumes successfully
  • Drivers that don’t require attach but has missing CSIDriver objects should successfully mount volumes without attachment(and no external-attacher running) if CSIDriver object is created later on.

Graduation Criteria

Alpha -> Beta

• Basic unit and e2e tests as outlined in the test plan.

Beta -> GA

• Users deployed in production and have gone through at least one K8s upgrade.

Implementation History

• K8s 1.12: Alpha implementation
• K8s 1.14: Beta implementation
• K8s 1.18: GA implementation