feat(zfspv): adding snapshot and clone support for ZFSPV (#39)

This commits support snapshot and clone commands via CSI driver. User can create snap and clone using the following steps. 

Note:
- Snapshot is created via reconciliation CR
- Cloned volume will be on the same zpool where the snapshot is taken
- Cloned volume will have same properties as source volume. 

-----------------------------------
Create a Snapshotclass
```
kind: VolumeSnapshotClass
apiVersion: snapshot.storage.k8s.io/v1beta1
metadata:
  name: zfspv-snapclass
  annotations:
    snapshot.storage.kubernetes.io/is-default-class: "true"
driver: zfs.csi.openebs.io
deletionPolicy: Delete
```
Once snapshotclass is created, we can use this class to create a Snapshot 
```
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
  name: zfspv-snap
spec:
  volumeSnapshotClassName: zfspv-snapclass
  source:
    persistentVolumeClaimName: csi-zfspv
```
```
$ kubectl get volumesnapshot
NAME          AGE
zfspv-snap    7m52s
```
```
$ kubectl get volumesnapshot -o yaml
apiVersion: v1
items:
- apiVersion: snapshot.storage.k8s.io/v1beta1
  kind: VolumeSnapshot
  metadata:
    annotations:
      kubectl.kubernetes.io/last-applied-configuration: |
        {"apiVersion":"snapshot.storage.k8s.io/v1beta1","kind":"VolumeSnapshot","metadata":{"annotations":{},"name":"zfspv-snap","namespace":"default"},"spec":{"source":{"persistentVolumeClaimName":"csi-zfspv"},"volumeSnapshotClassName":"zfspv-snapclass"}}
    creationTimestamp: "2020-01-30T10:31:24Z"
    finalizers:
    - snapshot.storage.kubernetes.io/volumesnapshot-as-source-protection
    - snapshot.storage.kubernetes.io/volumesnapshot-bound-protection
    generation: 1
    name: zfspv-snap
    namespace: default
    resourceVersion: "30040"
    selfLink: /apis/snapshot.storage.k8s.io/v1beta1/namespaces/default/volumesnapshots/zfspv-snap
    uid: 1a5cf166-c599-4f58-9f3c-f1148be47fca
  spec:
    source:
      persistentVolumeClaimName: csi-zfspv
    volumeSnapshotClassName: zfspv-snapclass
  status:
    boundVolumeSnapshotContentName: snapcontent-1a5cf166-c599-4f58-9f3c-f1148be47fca
    creationTime: "2020-01-30T10:31:24Z"
    readyToUse: true
    restoreSize: "0"
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""
```


Openebs resource for the created snapshot 
```
$ kubectl get snap -n openebs -o yaml
apiVersion: v1
items:
- apiVersion: openebs.io/v1alpha1
  kind: ZFSSnapshot
  metadata:
    creationTimestamp: "2020-01-30T10:31:24Z"
    finalizers:
    - zfs.openebs.io/finalizer
    generation: 2
    labels:
      kubernetes.io/nodename: pawan-2
      openebs.io/persistent-volume: pvc-18cab7c3-ec5e-4264-8507-e6f7df4c789a
    name: snapshot-1a5cf166-c599-4f58-9f3c-f1148be47fca
    namespace: openebs
    resourceVersion: "30035"
    selfLink: /apis/openebs.io/v1alpha1/namespaces/openebs/zfssnapshots/snapshot-1a5cf166-c599-4f58-9f3c-f1148be47fca
    uid: e29d571c-42b5-4fb7-9110-e1cfc9b96641
  spec:
    capacity: "4294967296"
    fsType: zfs
    ownerNodeID: pawan-2
    poolName: zfspv-pool
    status: Ready
    volumeType: DATASET
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""
```

Create a clone volume
    
 We can provide a datasource as snapshot name to create a clone volume
    
```yaml
    kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
      name: zfspv-clone
    spec:
      storageClassName: openebs-zfspv
      dataSource:
        name: zfspv-snap
        kind: VolumeSnapshot
        apiGroup: snapshot.storage.k8s.io
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 4Gi
```
It will create a ZFS clone volume from the mentioned snapshot and create the PV on the same node where original volume is there.
    
Here, As resize is not supported yet, the clone PVC size should match the size of the snapshot.
Also, all the properties from the storageclass will not be considered for the clone case, it will take the properties from the snapshot and create the clone volume. One thing to note here is that, the storageclass in clone PVC should have the same poolname as that of the original volume as across the pool, clone is not supported.


Signed-off-by: Pawan <pawan@mayadata.io>

pkg/zfs/volume.go

@@ -19,7 +19,8 @@ import (
 	"os"
 
 	apis "github.com/openebs/zfs-localpv/pkg/apis/openebs.io/core/v1alpha1"
-	"github.com/openebs/zfs-localpv/pkg/builder"
+	"github.com/openebs/zfs-localpv/pkg/builder/snapbuilder"
+	"github.com/openebs/zfs-localpv/pkg/builder/volbuilder"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
@@ -31,10 +32,16 @@ const (
 	OpenEBSNamespaceKey string = "OPENEBS_NAMESPACE"
 	// ZFSFinalizer for the ZfsVolume CR
 	ZFSFinalizer string = "zfs.openebs.io/finalizer"
+	// ZFSVolKey for the ZfsSnapshot CR to store Persistence Volume name
+	ZFSVolKey string = "openebs.io/persistent-volume"
 	// ZFSNodeKey will be used to insert Label in ZfsVolume CR
 	ZFSNodeKey string = "kubernetes.io/nodename"
 	// ZFSTopologyKey is supported topology key for the zfs driver
 	ZFSTopologyKey string = "kubernetes.io/hostname"
+	// ZFSStatusPending shows object has not handled yet
+	ZFSStatusPending string = "Pending"
+	// ZFSStatusReady shows object has been processed
+	ZFSStatusReady string = "Ready"
 )
 
 var (
@@ -60,11 +67,10 @@ func init() {
 // ProvisionVolume creates a ZFSVolume(zv) CR,
 // watcher for zvc is present in CSI agent
 func ProvisionVolume(
-	size int64,
 	vol *apis.ZFSVolume,
 ) error {
 
-	_, err := builder.NewKubeclient().WithNamespace(OpenEBSNamespace).Create(vol)
+	_, err := volbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Create(vol)
 	if err == nil {
 		logrus.Infof("provisioned volume %s", vol.Name)
 	}
@@ -72,16 +78,40 @@ func ProvisionVolume(
 	return err
 }
 
+// ProvisionSnapshot creates a ZFSSnapshot CR,
+// watcher for zvc is present in CSI agent
+func ProvisionSnapshot(
+	snap *apis.ZFSSnapshot,
+) error {
+
+	_, err := snapbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Create(snap)
+	if err == nil {
+		logrus.Infof("provisioned snapshot %s", snap.Name)
+	}
+
+	return err
+}
+
+// DeleteSnapshot deletes the corresponding ZFSSnapshot CR
+func DeleteSnapshot(snapname string) (err error) {
+	err = snapbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Delete(snapname)
+	if err == nil {
+		logrus.Infof("deprovisioned snapshot %s", snapname)
+	}
+
+	return
+}
+
 // GetVolume the corresponding ZFSVolume CR
 func GetVolume(volumeID string) (*apis.ZFSVolume, error) {
-	return builder.NewKubeclient().
+	return volbuilder.NewKubeclient().
 		WithNamespace(OpenEBSNamespace).
 		Get(volumeID, metav1.GetOptions{})
 }
 
 // DeleteVolume deletes the corresponding ZFSVol CR
 func DeleteVolume(volumeID string) (err error) {
-	err = builder.NewKubeclient().WithNamespace(OpenEBSNamespace).Delete(volumeID)
+	err = volbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Delete(volumeID)
 	if err == nil {
 		logrus.Infof("deprovisioned volume %s", volumeID)
 	}
@@ -95,15 +125,15 @@ func GetVolList(volumeID string) (*apis.ZFSVolumeList, error) {
 		LabelSelector: ZFSNodeKey + "=" + NodeID,
 	}
 
-	return builder.NewKubeclient().
+	return volbuilder.NewKubeclient().
 		WithNamespace(OpenEBSNamespace).List(listOptions)
 
 }
 
-// GetZFSVolume fetches the current Published csi Volume
+// GetZFSVolume fetches the given ZFSVolume
 func GetZFSVolume(volumeID string) (*apis.ZFSVolume, error) {
 	getOptions := metav1.GetOptions{}
-	vol, err := builder.NewKubeclient().
+	vol, err := volbuilder.NewKubeclient().
 		WithNamespace(OpenEBSNamespace).Get(volumeID, getOptions)
 	return vol, err
 }
@@ -117,7 +147,7 @@ func UpdateZvolInfo(vol *apis.ZFSVolume) error {
 		return nil
 	}
 
-	newVol, err := builder.BuildFrom(vol).
+	newVol, err := volbuilder.BuildFrom(vol).
 		WithFinalizer(finalizers).
 		WithLabels(labels).Build()
 
@@ -125,7 +155,7 @@ func UpdateZvolInfo(vol *apis.ZFSVolume) error {
 		return err
 	}
 
-	_, err = builder.NewKubeclient().WithNamespace(OpenEBSNamespace).Update(newVol)
+	_, err = volbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Update(newVol)
 	return err
 }
 
@@ -133,6 +163,61 @@ func UpdateZvolInfo(vol *apis.ZFSVolume) error {
 func RemoveZvolFinalizer(vol *apis.ZFSVolume) error {
 	vol.Finalizers = nil
 
-	_, err := builder.NewKubeclient().WithNamespace(OpenEBSNamespace).Update(vol)
+	_, err := volbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Update(vol)
+	return err
+}
+
+// GetZFSSnapshot fetches the given ZFSSnapshot
+func GetZFSSnapshot(snapID string) (*apis.ZFSSnapshot, error) {
+	getOptions := metav1.GetOptions{}
+	snap, err := snapbuilder.NewKubeclient().
+		WithNamespace(OpenEBSNamespace).Get(snapID, getOptions)
+	return snap, err
+}
+
+// GetZFSSnapshotStatus returns ZFSSnapshot status
+func GetZFSSnapshotStatus(snapID string) (string, error) {
+	getOptions := metav1.GetOptions{}
+	snap, err := snapbuilder.NewKubeclient().
+		WithNamespace(OpenEBSNamespace).Get(snapID, getOptions)
+
+	if err != nil {
+		logrus.Errorf("Get snapshot failed %s err: %s", snap.Name, err.Error())
+		return "", err
+	}
+
+	return snap.Status.State, nil
+}
+
+// UpdateSnapInfo updates ZFSSnapshot CR with node id and finalizer
+func UpdateSnapInfo(snap *apis.ZFSSnapshot) error {
+	finalizers := []string{ZFSFinalizer}
+	labels := map[string]string{ZFSNodeKey: NodeID}
+
+	if snap.Finalizers != nil {
+		return nil
+	}
+
+	newSnap, err := snapbuilder.BuildFrom(snap).
+		WithFinalizer(finalizers).
+		WithLabels(labels).Build()
+
+	// set the status to ready
+	newSnap.Status.State = ZFSStatusReady
+
+	if err != nil {
+		logrus.Errorf("Update snapshot failed %s err: %s", snap.Name, err.Error())
+		return err
+	}
+
+	_, err = snapbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Update(newSnap)
+	return err
+}
+
+// RemoveSnapFinalizer adds finalizer to ZFSSnapshot CR
+func RemoveSnapFinalizer(snap *apis.ZFSSnapshot) error {
+	snap.Finalizers = nil
+
+	_, err := snapbuilder.NewKubeclient().WithNamespace(OpenEBSNamespace).Update(snap)
 	return err
 }