Support cachingMode modification through VolumeAttributeClass

[Copilot]

Problem

The cachingMode parameter could only be set at volume creation time. Users needed to recreate volumes to change caching behavior.

Solution

Add cachingMode support to ControllerModifyVolume. Since cachingMode is an attachment-level property (not persisted in Azure disk metadata), the driver validates the parameter and the external-resizer updates the PV's volumeAttributes. The new caching mode applies on next attachment.

Changes

• Validation logic

  • Added ValidateCachingModeForSKU() function to validate compatibility (PremiumV2_LRS and UltraSSD_LRS require None)
  • Shared between ParseDiskParameters() and ControllerModifyVolume()

• ControllerModifyVolume

  • Parse and validate cachingMode from MutableParameters
  • Added getDiskSKUName() helper for safe SKU extraction

• Documentation

  • Updated VolumeAttributeClass parameter table
  • Added example configurations

Example Usage

apiVersion: storage.k8s.io/v1alpha1
kind: VolumeAttributesClass
metadata:
  name: azure-disk-caching-readonly
driverName: disk.csi.azure.com
parameters:
  cachingMode: "ReadOnly"

After patching a PVC to use this VAC, the caching mode changes take effect when the volume is re-attached (pod restart, node restart, etc.).

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• login.microsoftonline.com
  • Triggering command: /tmp/go-build1834556328/b001/azuredisk.test /tmp/go-build1834556328/b001/azuredisk.test -test.testlogfile=/tmp/go-build1834556328/b001/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true driver/azuredisk-errorsas cfg ux_amd64/vet /fileserviceprop/opt/hostedtoolcache/go/1.24.11/x64/pkg/tool/linux_amd64/vet /fileserviceprop-atomic -lang=go1.24 ux_amd64/vet -o 412366/b1103/_pk-errorsas k/azuredisk-csi--ifaceassert ux_amd64/vet tion_v1/reflectiumount tion_v1/reflecti/tmp/kubelet-detect-safe-umount373984403 -lang=go1.24 ux_amd64/vet (dns block)
  • Triggering command: /tmp/go-build85801472/b1217/azuredisk.test /tmp/go-build85801472/b1217/azuredisk.test -test.testlogfile=/tmp/go-build85801472/b1217/testlog.txt -test.paniconexit0 -test.gocoverdir=/tmp/go-build85801472/b1217/gocoverdir -test.timeout=10m0s -test.v=true cfg ux_amd64/vet til.go k8s.io/client-go/tmp/kubelet-detect-safe-umount2871886555 -lang=go1.24 ux_amd64/vet (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Support changing cachingMode through VolumeAttributeClass</issue_title>
<issue_description>Is your feature request related to a problem?/Why is this needed

Right now, the only way to change the cachingMode of a volume seems to be to re-create it. It would be great if this would be possible through a VolumeAttributeClass.

Describe the solution you'd like in detail

Describe alternatives you've considered

Additional context

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Support changing cachingMode through VolumeAttributeClass #3471

---

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[k8s-ci-robot]

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