discover existing on-disk snapshots

Signed-off-by: Ashish Amarnath <[email protected]>

Author: ashish-amarnath

pkg/hostpath/controllerserver.go

@@ -281,8 +281,8 @@ func (cs *controllerServer) ListVolumes(ctx context.Context, req *csi.ListVolume
 }
 
 // getSnapshotPath returns the full path to where the snapshot is stored
-func getSnapshotPath(snapshotId string) string {
-	return filepath.Join(dataRoot, fmt.Sprintf("%s.snap", snapshotId))
+func getSnapshotPath(snapshotID string) string {
+	return filepath.Join(dataRoot, fmt.Sprintf("%s%s", snapshotID, snapshotExt))
 }
 
 // CreateSnapshot uses tar command to create snapshot for hostpath volume. The tar command can quickly create

pkg/hostpath/hostpath.go

@@ -20,8 +20,10 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/golang/glog"
 	"google.golang.org/grpc/codes"
@@ -87,6 +89,9 @@ const (
 	// This can be ephemeral within the container or persisted if
 	// backed by a Pod volume.
 	dataRoot = "/csi-data-dir"
+
+	// Extension with which snapshot files will be saved.
+	snapshotExt = ".snap"
 )
 
 func init() {
@@ -127,12 +132,42 @@ func NewHostPathDriver(driverName, nodeID, endpoint string, ephemeral bool, maxV
 	}, nil
 }
 
+func getSnapshotID(file string) (bool, string) {
+	glog.V(4).Infof("file: %s", file)
+	// Files with .snap extension are volumesnapshot files.
+	// e.g. foo.snap, foo.bar.snap
+	if filepath.Ext(file) == snapshotExt {
+		return true, strings.TrimSuffix(file, snapshotExt)
+	}
+	return false, ""
+}
+
+func discoverExistingSnapshots() {
+	glog.V(4).Infof("discovering existing snapshots in %s", dataRoot)
+	files, err := ioutil.ReadDir(dataRoot)
+	if err != nil {
+		glog.Errorf("failed to discover snapshots under %s: %v", dataRoot, err)
+	}
+	for _, file := range files {
+		isSnapshot, snapshotID := getSnapshotID(file.Name())
+		if isSnapshot {
+			glog.V(4).Infof("adding snapshot %s from file %s", snapshotID, file.Name())
+			hostPathVolumeSnapshots[snapshotID] = hostPathSnapshot{
+				Id:         snapshotID,
+				Path:       file.Name(),
+				ReadyToUse: true,
+			}
+		}
+	}
+}
+
 func (hp *hostPath) Run() {
 	// Create GRPC servers
 	hp.ids = NewIdentityServer(hp.name, hp.version)
 	hp.ns = NewNodeServer(hp.nodeID, hp.ephemeral, hp.maxVolumesPerNode)
 	hp.cs = NewControllerServer(hp.ephemeral, hp.nodeID)
 
+	discoverExistingSnapshots()
 	s := NewNonBlockingGRPCServer()
 	s.Start(hp.endpoint, hp.ids, hp.cs, hp.ns)
 	s.Wait()

pkg/hostpath/hostpath_test.go

@@ -0,0 +1,67 @@
+/*
+Copyright 2020 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 hostpath
+
+import (
+	"testing"
+)
+
+func TestGetSnapshotID(t *testing.T) {
+	testCases := []struct {
+		name               string
+		inputPath          string
+		expectedIsSnapshot bool
+		expectedSnapshotID string
+	}{
+		{
+			name:               "should recognize foo.snap as a valid snapshot with ID foo",
+			inputPath:          "foo.snap",
+			expectedIsSnapshot: true,
+			expectedSnapshotID: "foo",
+		},
+		{
+			name:               "should recognize baz.tar.gz as an invalid snapshot",
+			inputPath:          "baz.tar.gz",
+			expectedIsSnapshot: false,
+			expectedSnapshotID: "",
+		},
+		{
+			name:               "should recognize baz.tar.snap as a valid snapshot with ID baz.tar",
+			inputPath:          "baz.tar.snap",
+			expectedIsSnapshot: true,
+			expectedSnapshotID: "baz.tar",
+		},
+		{
+			name:               "should recognize baz.tar.snap.snap as a valid snapshot with ID baz.tar.snap",
+			inputPath:          "baz.tar.snap.snap",
+			expectedIsSnapshot: true,
+			expectedSnapshotID: "baz.tar.snap",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			actualIsSnapshot, actualSnapshotID := getSnapshotID(tc.inputPath)
+			if actualIsSnapshot != tc.expectedIsSnapshot {
+				t.Errorf("unexpected result for path %s, Want: %t, Got: %t", tc.inputPath, tc.expectedIsSnapshot, actualIsSnapshot)
+			}
+			if actualSnapshotID != tc.expectedSnapshotID {
+				t.Errorf("unexpected snapshotID for path %s, Want: %s; Got :%s", tc.inputPath, tc.expectedSnapshotID, actualSnapshotID)
+			}
+		})
+	}
+}