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Map PV access modes to CSI access modes
Additionally enforce ReadWriteOncePod can only be used by itself
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‎accessmodes/access_modes.go

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/*
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Copyright 2021 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package accessmodes
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import (
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"fmt"
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"github.com/container-storage-interface/spec/lib/go/csi"
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v1 "k8s.io/api/core/v1"
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)
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// ToCSIAccessMode maps PersistentVolume access modes in Kubernetes to CSI
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// access modes. Which mapping is used depends if the driver supports the
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// SINGLE_NODE_MULTI_WRITER capability.
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func ToCSIAccessMode(pvAccessModes []v1.PersistentVolumeAccessMode, supportsSingleNodeMultiWriter bool) (csi.VolumeCapability_AccessMode_Mode, error) {
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if supportsSingleNodeMultiWriter {
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return toSingleNodeMultiWriterCapableCSIAccessMode(pvAccessModes)
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}
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return toCSIAccessMode(pvAccessModes)
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}
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// toCSIAccessMode maps PersistentVolume access modes in Kubernetes to CSI
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// access modes.
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//
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// +------------------+-------------------------+----------------------------------------+
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// | K8s AccessMode | CSI AccessMode | Additional Details |
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// +------------------+-------------------------+----------------------------------------+
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// | ReadWriteMany | MULTI_NODE_MULTI_WRITER | |
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// | ReadOnlyMany | MULTI_NODE_READER_ONLY | Cannot be combined with ReadWriteOnce |
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// | ReadWriteOnce | SINGLE_NODE_WRITER | Cannot be combined with ReadOnlyMany |
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// | ReadWriteOncePod | SINGLE_NODE_WRITER | Cannot be combined with any AccessMode |
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// +------------------+-------------------------+----------------------------------------+
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func toCSIAccessMode(pvAccessModes []v1.PersistentVolumeAccessMode) (csi.VolumeCapability_AccessMode_Mode, error) {
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m := uniqueAccessModes(pvAccessModes)
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switch {
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// This mapping exists to enable CSI drivers that lack the
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// SINGLE_NODE_MULTI_WRITER capability to work with the
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// ReadWriteOncePod access mode.
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case m[v1.ReadWriteOncePod]:
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if len(m) > 1 {
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return csi.VolumeCapability_AccessMode_UNKNOWN, fmt.Errorf("Kubernetes does not support use of ReadWriteOncePod with other access modes on the same PersistentVolume")
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}
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return csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER, nil
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case m[v1.ReadWriteMany]:
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// ReadWriteMany takes precedence, regardless of what other
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// modes are set.
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return csi.VolumeCapability_AccessMode_MULTI_NODE_MULTI_WRITER, nil
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case m[v1.ReadOnlyMany] && m[v1.ReadWriteOnce]:
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// This is not possible in the CSI spec.
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return csi.VolumeCapability_AccessMode_UNKNOWN, fmt.Errorf("CSI does not support ReadOnlyMany and ReadWriteOnce on the same PersistentVolume")
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case m[v1.ReadOnlyMany]:
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return csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY, nil
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case m[v1.ReadWriteOnce]:
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return csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER, nil
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default:
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return csi.VolumeCapability_AccessMode_UNKNOWN, fmt.Errorf("unsupported AccessMode combination: %+v", pvAccessModes)
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}
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}
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// toSingleNodeMultiWriterCapableCSIAccessMode maps PersistentVolume access
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// modes in Kubernetes to CSI access modes for drivers that support the
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// SINGLE_NODE_MULTI_WRITER capability.
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//
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// +------------------+---------------------------+----------------------------------------+
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// | K8s AccessMode | CSI AccessMode | Additional Details |
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// +------------------+---------------------------+----------------------------------------+
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// | ReadWriteMany | MULTI_NODE_MULTI_WRITER | |
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// | ReadOnlyMany | MULTI_NODE_READER_ONLY | Cannot be combined with ReadWriteOnce |
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// | ReadWriteOnce | SINGLE_NODE_MULTI_WRITER | Cannot be combined with ReadOnlyMany |
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// | ReadWriteOncePod | SINGLE_NODE_SINGLE_WRITER | Cannot be combined with any AccessMode |
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// +------------------+---------------------------+----------------------------------------+
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func toSingleNodeMultiWriterCapableCSIAccessMode(pvAccessModes []v1.PersistentVolumeAccessMode) (csi.VolumeCapability_AccessMode_Mode, error) {
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m := uniqueAccessModes(pvAccessModes)
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switch {
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case m[v1.ReadWriteOncePod]:
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if len(m) > 1 {
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return csi.VolumeCapability_AccessMode_UNKNOWN, fmt.Errorf("Kubernetes does not support use of ReadWriteOncePod with other access modes on the same PersistentVolume")
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}
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return csi.VolumeCapability_AccessMode_SINGLE_NODE_SINGLE_WRITER, nil
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case m[v1.ReadWriteMany]:
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// ReadWriteMany trumps everything, regardless of what other
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// modes are set.
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return csi.VolumeCapability_AccessMode_MULTI_NODE_MULTI_WRITER, nil
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case m[v1.ReadOnlyMany] && m[v1.ReadWriteOnce]:
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// This is not possible in the CSI spec.
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return csi.VolumeCapability_AccessMode_UNKNOWN, fmt.Errorf("CSI does not support ReadOnlyMany and ReadWriteOnce on the same PersistentVolume")
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case m[v1.ReadOnlyMany]:
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return csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY, nil
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case m[v1.ReadWriteOnce]:
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return csi.VolumeCapability_AccessMode_SINGLE_NODE_MULTI_WRITER, nil
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default:
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return csi.VolumeCapability_AccessMode_UNKNOWN, fmt.Errorf("unsupported AccessMode combination: %+v", pvAccessModes)
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}
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}
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func uniqueAccessModes(pvAccessModes []v1.PersistentVolumeAccessMode) map[v1.PersistentVolumeAccessMode]bool {
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m := map[v1.PersistentVolumeAccessMode]bool{}
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for _, mode := range pvAccessModes {
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m[mode] = true
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}
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return m
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}

‎accessmodes/access_modes_test.go

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/*
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Copyright 2021 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package accessmodes
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import (
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"testing"
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"github.com/container-storage-interface/spec/lib/go/csi"
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v1 "k8s.io/api/core/v1"
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)
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func TestToCSIAccessMode(t *testing.T) {
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tests := []struct {
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name string
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pvAccessModes []v1.PersistentVolumeAccessMode
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expectedCSIAccessMode csi.VolumeCapability_AccessMode_Mode
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expectError bool
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supportsSingleNodeMultiWriter bool
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}{
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{
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name: "RWX",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadWriteMany},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_MULTI_NODE_MULTI_WRITER,
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},
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{
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name: "ROX + RWO",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadOnlyMany, v1.ReadWriteOnce},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_UNKNOWN,
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expectError: true,
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},
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{
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name: "ROX + RWOP",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadOnlyMany, v1.ReadWriteOncePod},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_UNKNOWN,
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expectError: true,
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},
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{
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name: "ROX",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadOnlyMany},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY,
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},
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{
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name: "RWO",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadWriteOnce},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER,
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},
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{
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name: "RWOP",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadWriteOncePod},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER,
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},
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{
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name: "empty",
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pvAccessModes: []v1.PersistentVolumeAccessMode{},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_UNKNOWN,
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expectError: true,
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},
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{
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name: "RWX with SINGLE_NODE_MULTI_WRITER capable driver",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadWriteMany},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_MULTI_NODE_MULTI_WRITER,
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supportsSingleNodeMultiWriter: true,
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},
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{
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name: "ROX + RWO with SINGLE_NODE_MULTI_WRITER capable driver",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadOnlyMany, v1.ReadWriteOnce},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_UNKNOWN,
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expectError: true,
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supportsSingleNodeMultiWriter: true,
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},
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{
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name: "ROX + RWOP with SINGLE_NODE_MULTI_WRITER capable driver",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadOnlyMany, v1.ReadWriteOncePod},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_UNKNOWN,
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expectError: true,
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supportsSingleNodeMultiWriter: true,
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},
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{
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name: "ROX with SINGLE_NODE_MULTI_WRITER capable driver",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadOnlyMany},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY,
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supportsSingleNodeMultiWriter: true,
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},
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{
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name: "RWO with SINGLE_NODE_MULTI_WRITER capable driver",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadWriteOnce},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_SINGLE_NODE_MULTI_WRITER,
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supportsSingleNodeMultiWriter: true,
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},
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{
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name: "RWOP with SINGLE_NODE_MULTI_WRITER capable driver",
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pvAccessModes: []v1.PersistentVolumeAccessMode{v1.ReadWriteOncePod},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_SINGLE_NODE_SINGLE_WRITER,
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supportsSingleNodeMultiWriter: true,
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},
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{
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name: "empty with SINGLE_NODE_MULTI_WRITER capable driver",
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pvAccessModes: []v1.PersistentVolumeAccessMode{},
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expectedCSIAccessMode: csi.VolumeCapability_AccessMode_UNKNOWN,
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expectError: true,
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supportsSingleNodeMultiWriter: true,
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},
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}
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for _, test := range tests {
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t.Run(test.name, func(t *testing.T) {
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csiAccessMode, err := ToCSIAccessMode(test.pvAccessModes, test.supportsSingleNodeMultiWriter)
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if err == nil && test.expectError {
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t.Errorf("test %s: expected error, got none", test.name)
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}
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if err != nil && !test.expectError {
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t.Errorf("test %s: got error: %s", test.name, err)
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}
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if !test.expectError && csiAccessMode != test.expectedCSIAccessMode {
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t.Errorf("test %s: unexpected access mode: %+v", test.name, csiAccessMode)
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}
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})
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}
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}

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