Split plugin framework into its own package

Signed-off-by: Carlisia <carlisiac@vmware.com>

pkg/plugin/framework/examples_test.go

@@ -0,0 +1,93 @@
+/*
+Copyright 2019 the Velero contributors.
+
+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 framework
+
+import (
+	"github.com/sirupsen/logrus"
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+func ExampleNewServer_blockStore() {
+	NewServer(). // call the server
+			RegisterBlockStore("example-blockstore", newBlockStore). // register the plugin
+			Serve()                                                  // serve the plugin
+}
+
+func newBlockStore(logger logrus.FieldLogger) (interface{}, error) {
+	return &BlockStore{FieldLogger: logger}, nil
+}
+
+type BlockStore struct {
+	FieldLogger logrus.FieldLogger
+}
+
+// Implement all methods for the BlockStore interface...
+func (b *BlockStore) Init(config map[string]string) error {
+	b.FieldLogger.Infof("BlockStore.Init called")
+
+	// ...
+
+	return nil
+}
+
+func (b *BlockStore) CreateVolumeFromSnapshot(snapshotID, volumeType, volumeAZ string, iops *int64) (volumeID string, err error) {
+	b.FieldLogger.Infof("CreateVolumeFromSnapshot called")
+
+	// ...
+
+	return "volumeID", nil
+}
+
+func (b *BlockStore) GetVolumeID(pv runtime.Unstructured) (string, error) {
+	b.FieldLogger.Infof("GetVolumeID called")
+
+	// ...
+
+	return "volumeID", nil
+}
+
+func (b *BlockStore) SetVolumeID(pv runtime.Unstructured, volumeID string) (runtime.Unstructured, error) {
+	b.FieldLogger.Infof("SetVolumeID called")
+
+	// ...
+
+	return nil, nil
+}
+
+func (b *BlockStore) GetVolumeInfo(volumeID, volumeAZ string) (string, *int64, error) {
+	b.FieldLogger.Infof("GetVolumeInfo called")
+
+	// ...
+
+	return "volumeFilesystemType", nil, nil
+}
+
+func (b *BlockStore) CreateSnapshot(volumeID, volumeAZ string, tags map[string]string) (snapshotID string, err error) {
+	b.FieldLogger.Infof("CreateSnapshot called")
+
+	// ...
+
+	return "snapshotID", nil
+}
+
+func (b *BlockStore) DeleteSnapshot(snapshotID string) error {
+	b.FieldLogger.Infof("DeleteSnapshot called")
+
+	// ...
+
+	return nil
+}