Add ImageVolumeSource implementation

This patch adds the kubelet implementation of the image volume source
feature.

Signed-off-by: Sascha Grunert <sgrunert@redhat.com>

pkg/volume/image/OWNERS

@@ -0,0 +1,9 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+approvers:
+  - sig-node-approvers
+reviewers:
+  - sig-node-reviewers
+labels:
+  - sig/node
+  - area/kubelet

pkg/volume/image/image.go

@@ -0,0 +1,83 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package image
+
+import (
+	v1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/kubernetes/pkg/volume"
+)
+
+// imagePlugin is the image volume plugin which acts as a stub to provide the
+// functionality the volume manager expects. The real volume source
+// implementation is part of the kubelet code and gated by the Kubernetes
+// feature "ImageVolume"
+// See: https://kep.k8s.io/4639
+type imagePlugin struct {
+	spec *volume.Spec
+	volume.MetricsNil
+}
+
+var _ volume.VolumePlugin = &imagePlugin{}
+var _ volume.Mounter = &imagePlugin{}
+var _ volume.Unmounter = &imagePlugin{}
+var _ volume.Volume = &imagePlugin{}
+
+const pluginName = "kubernetes.io/image"
+
+func ProbeVolumePlugins() []volume.VolumePlugin {
+	p := &imagePlugin{}
+	return []volume.VolumePlugin{p}
+}
+
+func (o *imagePlugin) Init(volume.VolumeHost) error                    { return nil }
+func (o *imagePlugin) GetPluginName() string                           { return pluginName }
+func (o *imagePlugin) GetVolumeName(spec *volume.Spec) (string, error) { return o.spec.Name(), nil }
+
+func (o *imagePlugin) CanSupport(spec *volume.Spec) bool {
+	return spec.Volume.Image != nil
+}
+
+func (o *imagePlugin) NewMounter(spec *volume.Spec, podRef *v1.Pod, opts volume.VolumeOptions) (volume.Mounter, error) {
+	return o, nil
+}
+
+func (o *imagePlugin) NewUnmounter(name string, podUID types.UID) (volume.Unmounter, error) {
+	return o, nil
+}
+
+func (o *imagePlugin) ConstructVolumeSpec(volumeName, mountPath string) (volume.ReconstructedVolume, error) {
+	return volume.ReconstructedVolume{Spec: o.spec}, nil
+}
+
+func (o *imagePlugin) GetAttributes() volume.Attributes {
+	return volume.Attributes{
+		ReadOnly:       true,
+		Managed:        true,
+		SELinuxRelabel: true,
+	}
+}
+
+func (o *imagePlugin) GetPath() string                                             { return "" }
+func (o *imagePlugin) RequiresFSResize() bool                                      { return false }
+func (o *imagePlugin) RequiresRemount(spec *volume.Spec) bool                      { return false }
+func (o *imagePlugin) SetUp(mounterArgs volume.MounterArgs) error                  { return nil }
+func (o *imagePlugin) SetUpAt(dir string, mounterArgs volume.MounterArgs) error    { return nil }
+func (o *imagePlugin) SupportsMountOption() bool                                   { return false }
+func (o *imagePlugin) SupportsSELinuxContextMount(spec *volume.Spec) (bool, error) { return false, nil }
+func (o *imagePlugin) TearDown() error                                             { return nil }
+func (o *imagePlugin) TearDownAt(string) error                                     { return nil }