Verification package: Verified given data-dir.

For now verifies whete Backend.cindex is consistent with WAL log,
but should get expanded to cover memberships & revisions.

server/wal/wal.go

@@ -618,10 +618,11 @@ func ValidSnapshotEntries(lg *zap.Logger, walDir string) ([]walpb.Snapshot, erro
 // If it cannot read out the expected snap, it will return ErrSnapshotNotFound.
 // If the loaded snap doesn't match with the expected one, it will
 // return error ErrSnapshotMismatch.
-func Verify(lg *zap.Logger, walDir string, snap walpb.Snapshot) error {
+func Verify(lg *zap.Logger, walDir string, snap walpb.Snapshot) (*raftpb.HardState, error) {
 	var metadata []byte
 	var err error
 	var match bool
+	var state raftpb.HardState
 
 	rec := &walpb.Record{}
 
@@ -630,14 +631,14 @@ func Verify(lg *zap.Logger, walDir string, snap walpb.Snapshot) error {
 	}
 	names, nameIndex, err := selectWALFiles(lg, walDir, snap)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	// open wal files in read mode, so that there is no conflict
 	// when the same WAL is opened elsewhere in write mode
 	rs, _, closer, err := openWALFiles(lg, walDir, names, nameIndex, false)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	defer func() {
 		if closer != nil {
@@ -652,7 +653,7 @@ func Verify(lg *zap.Logger, walDir string, snap walpb.Snapshot) error {
 		switch rec.Type {
 		case metadataType:
 			if metadata != nil && !bytes.Equal(metadata, rec.Data) {
-				return ErrMetadataConflict
+				return nil, ErrMetadataConflict
 			}
 			metadata = rec.Data
 		case crcType:
@@ -660,7 +661,7 @@ func Verify(lg *zap.Logger, walDir string, snap walpb.Snapshot) error {
 			// Current crc of decoder must match the crc of the record.
 			// We need not match 0 crc, since the decoder is a new one at this point.
 			if crc != 0 && rec.Validate(crc) != nil {
-				return ErrCRCMismatch
+				return nil, ErrCRCMismatch
 			}
 			decoder.updateCRC(rec.Crc)
 		case snapshotType:
@@ -668,7 +669,7 @@ func Verify(lg *zap.Logger, walDir string, snap walpb.Snapshot) error {
 			pbutil.MustUnmarshal(&loadedSnap, rec.Data)
 			if loadedSnap.Index == snap.Index {
 				if loadedSnap.Term != snap.Term {
-					return ErrSnapshotMismatch
+					return nil, ErrSnapshotMismatch
 				}
 				match = true
 			}
@@ -676,22 +677,23 @@ func Verify(lg *zap.Logger, walDir string, snap walpb.Snapshot) error {
 		// are not necessary for validating the WAL contents
 		case entryType:
 		case stateType:
+			pbutil.MustUnmarshal(&state, rec.Data)
 		default:
-			return fmt.Errorf("unexpected block type %d", rec.Type)
+			return nil, fmt.Errorf("unexpected block type %d", rec.Type)
 		}
 	}
 
 	// We do not have to read out all the WAL entries
 	// as the decoder is opened in read mode.
 	if err != io.EOF && err != io.ErrUnexpectedEOF {
-		return err
+		return nil, err
 	}
 
 	if !match {
-		return ErrSnapshotNotFound
+		return nil, ErrSnapshotNotFound
 	}
 
-	return nil
+	return &state, nil
 }
 
 // cut closes current file written and creates a new one ready to append.

server/wal/wal_test.go

@@ -27,10 +27,12 @@ import (
 	"regexp"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"go.etcd.io/etcd/client/pkg/v3/fileutil"
 	"go.etcd.io/etcd/pkg/v3/pbutil"
 	"go.etcd.io/etcd/raft/v3/raftpb"
 	"go.etcd.io/etcd/server/v3/wal/walpb"
+	"go.uber.org/zap/zaptest"
 
 	"go.uber.org/zap"
 )
@@ -231,14 +233,14 @@ func TestOpenAtIndex(t *testing.T) {
 // The test creates a WAL directory and cuts out multiple WAL files. Then
 // it corrupts one of the files by completely truncating it.
 func TestVerify(t *testing.T) {
+	lg := zaptest.NewLogger(t)
 	walDir, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer os.RemoveAll(walDir)
 
 	// create WAL
-	w, err := Create(zap.NewExample(), walDir, nil)
+	w, err := Create(lg, walDir, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -255,11 +257,15 @@ func TestVerify(t *testing.T) {
 		}
 	}
 
+	hs := raftpb.HardState{Term: 1, Vote: 3, Commit: 5}
+	assert.NoError(t, w.Save(hs, nil))
+
 	// to verify the WAL is not corrupted at this point
-	err = Verify(zap.NewExample(), walDir, walpb.Snapshot{})
+	hardstate, err := Verify(lg, walDir, walpb.Snapshot{})
 	if err != nil {
 		t.Errorf("expected a nil error, got %v", err)
 	}
+	assert.Equal(t, hs, *hardstate)
 
 	walFiles, err := ioutil.ReadDir(walDir)
 	if err != nil {
@@ -272,7 +278,7 @@ func TestVerify(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = Verify(zap.NewExample(), walDir, walpb.Snapshot{})
+	_, err = Verify(lg, walDir, walpb.Snapshot{})
 	if err == nil {
 		t.Error("expected a non-nil error, got nil")
 	}