feat(zfspv): adding backup and restore support (#162)

This commit adds support for Backup and Restore controller, which will be watching for
the events. The velero plugin will create a Backup CR to create a backup
with the remote location information, the controller will send the data
to that remote location.

In the same way, the velero plugin will create a Restore CR to restore the
volume from the the remote location and the restore controller will restore
the data.

Steps to use velero plugin for ZFS-LocalPV are :

1. install velero

2. add openebs plugin

velero plugin add openebs/velero-plugin:latest

3. Create the volumesnapshot location :

for full backup :-

```yaml
apiVersion: velero.io/v1
kind: VolumeSnapshotLocation
metadata:
  name: default
  namespace: velero
spec:
  provider: openebs.io/zfspv-blockstore
  config:
    bucket: velero
    prefix: zfs
    namespace: openebs
    provider: aws
    region: minio
    s3ForcePathStyle: "true"
    s3Url: http://minio.velero.svc:9000
```

for incremental backup :-

```yaml
apiVersion: velero.io/v1
kind: VolumeSnapshotLocation
metadata:
  name: default
  namespace: velero
spec:
  provider: openebs.io/zfspv-blockstore
  config:
    bucket: velero
    prefix: zfs
    backup: incremental
    namespace: openebs
    provider: aws
    region: minio
    s3ForcePathStyle: "true"
    s3Url: http://minio.velero.svc:9000
```

4. Create backup

velero backup create my-backup --snapshot-volumes --include-namespaces=velero-ns --volume-snapshot-locations=aws-cloud-default --storage-location=default

5. Create Schedule

velero create schedule newschedule  --schedule="*/1 * * * *" --snapshot-volumes --include-namespaces=velero-ns --volume-snapshot-locations=aws-local-default --storage-location=default

6. Restore from backup

velero restore create --from-backup my-backup --restore-volumes=true --namespace-mappings velero-ns:ns1



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

pkg/builder/bkpbuilder/buildlist.go

@@ -0,0 +1,72 @@
+/*
+Copyright 2020 The OpenEBS 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 bkpbuilder
+
+import (
+	apis "github.com/openebs/zfs-localpv/pkg/apis/openebs.io/zfs/v1"
+)
+
+// ListBuilder enables building an instance of
+// ZFSBackupList
+type ListBuilder struct {
+	list    *apis.ZFSBackupList
+	filters predicateList
+}
+
+// NewListBuilder returns a new instance of ListBuilder
+func NewListBuilder() *ListBuilder {
+	return &ListBuilder{
+		list: &apis.ZFSBackupList{},
+	}
+}
+
+// ListBuilderFrom returns a new instance of
+// ListBuilder from API list instance
+func ListBuilderFrom(bkps apis.ZFSBackupList) *ListBuilder {
+	b := &ListBuilder{list: &apis.ZFSBackupList{}}
+	if len(bkps.Items) == 0 {
+		return b
+	}
+
+	b.list.Items = append(b.list.Items, bkps.Items...)
+	return b
+}
+
+// List returns the list of pod
+// instances that was built by this
+// builder
+func (b *ListBuilder) List() *apis.ZFSBackupList {
+	if b.filters == nil || len(b.filters) == 0 {
+		return b.list
+	}
+
+	filtered := &apis.ZFSBackupList{}
+	for _, bkp := range b.list.Items {
+		bkp := bkp // pin it
+		if b.filters.all(From(&bkp)) {
+			filtered.Items = append(filtered.Items, bkp)
+		}
+	}
+	return filtered
+}
+
+// WithFilter add filters on which the pod
+// has to be filtered
+func (b *ListBuilder) WithFilter(pred ...Predicate) *ListBuilder {
+	b.filters = append(b.filters, pred...)
+	return b
+}