Ephemeral volumes support

Added support for provisioning of ephemeral/csi-inline volumes. This only works
in Kubernetes v1.15+.

Kubernetes v1.15 does not provide any additional information about 'ephemeral'
volumes in NodePublishVolume() call. So, to address this issue, we assume to
create ephemeral volume if the following all cases are met:
  - Volume with given volume-id is not found
  - Missing StagingTargetPath in the NodePublishRequest
  - No provisioner information in NodePlubishRequest.VolumeContext

Added sample application deployment to illustrate ephemeral volume usage.

TODO: Extend e2e tests to ephemeral volumes.

README.md

@@ -325,7 +325,7 @@ can reuse existing local data when restarting.
 Volume | Kubernetes | PMEM-CSI | Limitations
 --- | --- | --- | ---
 Persistent | supported | supported | topology aware scheduling<sup>1</sup>
-Ephemeral | [in design](https://github.com/kubernetes/enhancements/blob/master/keps/sig-storage/20190122-csi-inline-volumes.md#proposal) | in design | topology aware scheduling<sup>1</sup>, resource constraints<sup>2</sup>
+Ephemeral | supported | supported | resource constraints<sup>2</sup>
 Cache | supported | supported | topology aware scheduling<sup>1</sup>
 
 <sup>1 </sup>[Topology aware
@@ -344,8 +344,8 @@ the node cannot start until resources become available.
 
 #### Usage on Kubernetes
 
-Kubernetes cluster administrators can expose above mentioned [volume
-persistency types](#volume-persistency) to applications using
+Kubernetes cluster administrators can expose above mentioned Persistent and Cache volumes
+to applications using
 [`StorageClass
 Parameters`](https://kubernetes.io/docs/concepts/storage/storage-classes/#parameters). An
 optional `persistencyModel` parameter differentiates how the
@@ -400,6 +400,9 @@ application](deploy/common/pmem-app-cache.yaml) example.
 * A node is only chosen the first time a pod starts. After that it will always restart
   on that node, because that is where the persistent volume was created.
 
+Volume requests embedded in Pod spec are provisioned as Ephemeral volumes. Check with
+provided [example application](deploy/kubernetes-1.15/pmem-app-ephemeral.yaml) for
+ephemeral volume usage.
 ## Prerequisites
 
 ### Software required
@@ -515,7 +518,7 @@ Kubernetes cluster has been verified on:
 |-------------------|--------------------------------|------------------------------- |
 | devel             | Kubernetes 1.13                | CSINodeInfo, CSIDriverRegistry |
 | devel             | Kubernetes 1.14                |                                |
-| devel             | Kubernetes 1.15                |                                |
+| devel             | Kubernetes 1.15                | CSIInlineVolume                |
 
 ## Setup
 

deploy/common/pmem-app-ephemeral.yaml

@@ -0,0 +1,22 @@
+# This demonstrates how to use inline pmem csi volumes
+kind: Pod
+apiVersion: v1
+metadata:
+  name: my-csi-app-inline-volume
+spec:
+  containers:
+    - name: my-frontend
+      image: busybox
+      command: [ "sleep", "100000" ]
+      volumeMounts:
+      - mountPath: "/data"
+        name: my-csi-volume
+  volumes:
+  - name: my-csi-volume
+    csi:
+      driver: pmem-csi.intel.com
+      fsType: "xfs"
+      volumeAttributes:
+        size: "2Gi"
+        nsmode: "fsdax"
+

deploy/kubernetes-1.15/pmem-app-cache.yaml

@@ -0,0 +1 @@
+../common/pmem-app-cache.yaml

deploy/kubernetes-1.15/pmem-app-ephemeral.yaml

@@ -0,0 +1 @@
+../common/pmem-app-ephemeral.yaml

deploy/kubernetes-1.15/pmem-app-late-binding.yaml

@@ -0,0 +1 @@
+../common/pmem-app-late-binding.yaml

deploy/kubernetes-1.15/pmem-app.yaml

@@ -0,0 +1 @@
+../common/pmem-app.yaml

deploy/kubernetes-1.15/pmem-pvc-cache.yaml

@@ -0,0 +1 @@
+../common/pmem-pvc-cache.yaml

deploy/kubernetes-1.15/pmem-pvc-late-binding.yaml

@@ -0,0 +1 @@
+../common/pmem-pvc-late-binding.yaml

deploy/kubernetes-1.15/pmem-pvc.yaml

@@ -0,0 +1 @@
+../common/pmem-pvc.yaml

deploy/kubernetes-1.15/pmem-storageclass-cache.yaml

@@ -0,0 +1 @@
+../common/pmem-storageclass-cache.yaml

deploy/kubernetes-1.15/pmem-storageclass-ext4.yaml

@@ -0,0 +1 @@
+../common/pmem-storageclass-ext4.yaml

deploy/kubernetes-1.15/pmem-storageclass-late-binding.yaml

@@ -0,0 +1 @@
+../common/pmem-storageclass-late-binding.yaml

deploy/kubernetes-1.15/pmem-storageclass-xfs.yaml

@@ -0,0 +1 @@
+../common/pmem-storageclass-xfs.yaml

pkg/pmem-csi-driver/controllerserver-master.go

@@ -37,9 +37,9 @@ const (
 	pmemParameterKeyPersistencyModel = "persistencyModel"
 	pmemParameterKeyCacheSize        = "cacheSize"
 
-	pmemPersistencyModelNone  PmemPersistencyModel = "none"
-	pmemPersistencyModelCache PmemPersistencyModel = "cache"
-	//pmemPersistencyModelEphemeral PmemPersistencyModel = "ephemeral"
+	pmemPersistencyModelNone      PmemPersistencyModel = "none"
+	pmemPersistencyModelCache     PmemPersistencyModel = "cache"
+	pmemPersistencyModelEphemeral PmemPersistencyModel = "ephemeral"
 )
 
 type PmemPersistencyModel string