Merge pull request #12735 from ptabor/20210227-reduce-store-v2-clean

no-store_v2: Store ConfState as part of WAL log snapshot
2024-09-27 06:25:44 +00:00 · 2021-03-25 08:23:00 +01:00 · 2021-03-25 08:23:00 +01:00 · 8ee1dd9e23
commit 8ee1dd9e23
parent 65d6a1f4bf 4d4c84e014
11 changed files with 202 additions and 75 deletions
--- a/contrib/raftexample/raft.go
+++ b/contrib/raftexample/raft.go
@ -117,8 +117,9 @@ func newRaftNode(id int, peers []string, join bool, getSnapshot func() ([]byte,

 func (rc *raftNode) saveSnap(snap raftpb.Snapshot) error {
 	walSnap := walpb.Snapshot{
-		Index: snap.Metadata.Index,
-		Term:  snap.Metadata.Term,
+		Index:     snap.Metadata.Index,
+		Term:      snap.Metadata.Term,
+		ConfState: &snap.Metadata.ConfState,
 	}
 	// save the snapshot file before writing the snapshot to the wal.
 	// This makes it possible for the snapshot file to become orphaned, but prevents
--- a/etcdctl/ctlv2/command/backup_command.go
+++ b/etcdctl/ctlv2/command/backup_command.go
@ -109,7 +109,7 @@ func saveSnap(destSnap, srcSnap string) (walsnap walpb.Snapshot) {
 		log.Fatal(err)
 	}
 	if snapshot != nil {
-		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
+		walsnap.Index, walsnap.Term, walsnap.ConfState = snapshot.Metadata.Index, snapshot.Metadata.Term, &snapshot.Metadata.ConfState
 		newss := snap.New(zap.NewExample(), destSnap)
 		if err = newss.SaveSnap(*snapshot); err != nil {
 			log.Fatal(err)
--- a/etcdctl/snapshot/v3_snapshot.go
+++ b/etcdctl/snapshot/v3_snapshot.go
@ -387,6 +387,8 @@ func (s *v3Manager) saveDB() error {
 }

 // saveWALAndSnap creates a WAL for the initial cluster
+//
+// TODO: This code ignores learners !!!
 func (s *v3Manager) saveWALAndSnap() error {
 	if err := fileutil.CreateDirAll(s.walDir); err != nil {
 		return err
@ -454,19 +456,20 @@ func (s *v3Manager) saveWALAndSnap() error {
 	if berr != nil {
 		return berr
 	}
+	confState := raftpb.ConfState{
+		Voters: nodeIDs,
+	}
 	raftSnap := raftpb.Snapshot{
 		Data: b,
 		Metadata: raftpb.SnapshotMetadata{
-			Index: commit,
-			Term:  term,
-			ConfState: raftpb.ConfState{
-				Voters: nodeIDs,
-			},
+			Index:     commit,
+			Term:      term,
+			ConfState: confState,
 		},
 	}
 	sn := snap.New(s.lg, s.snapDir)
 	if err := sn.SaveSnap(raftSnap); err != nil {
 		return err
 	}
-	return w.SaveSnapshot(walpb.Snapshot{Index: commit, Term: term})
+	return w.SaveSnapshot(walpb.Snapshot{Index: commit, Term: term, ConfState: &confState})
 }
--- a/scripts/genproto.sh
+++ b/scripts/genproto.sh
@ -39,10 +39,11 @@ log_callout -e "\\nRunning gofast (gogo) proto generation..."

 for dir in ${DIRS}; do
  run pushd "${dir}"
-    run protoc --gofast_out=plugins=grpc:. -I=".:${GOGOPROTO_PATH}:${ETCD_ROOT_DIR}/..:${GRPC_GATEWAY_ROOT}/third_party/googleapis" \
+    run protoc --gofast_out=plugins=grpc:. -I=".:${GOGOPROTO_PATH}:${ETCD_ROOT_DIR}/..:${ETCD_ROOT_DIR}:${GRPC_GATEWAY_ROOT}/third_party/googleapis" \
      --plugin="${GOFAST_BIN}" ./*.proto

-    sed -i.bak -E 's|"etcd/api/|"go.etcd.io/etcd/api/v3/|g' ./*.pb.go
+    run sed -i.bak -E 's|"etcd/api/|"go.etcd.io/etcd/api/v3/|g' ./*.pb.go
+    run sed -i.bak -E 's|"raft/raftpb"|"go.etcd.io/etcd/raft/v3/raftpb"|g' ./*.pb.go

    rm -f ./*.bak
    run gofmt -s -w ./*.pb.go
@ -69,13 +70,13 @@ for pb in api/etcdserverpb/rpc server/etcdserver/api/v3lock/v3lockpb/v3lock serv
  pkg=$(basename "${pkgpath}")
  gwfile="${pb}.pb.gw.go"

-  sed -i -E "s#package $pkg#package gw#g" "${gwfile}"
-  sed -i -E "s#import \\(#import \\(\"go.etcd.io/etcd/${pkgpath}\"#g" "${gwfile}"
-  sed -i -E "s#([ (])([a-zA-Z0-9_]*(Client|Server|Request)([^(]|$))#\\1${pkg}.\\2#g" "${gwfile}"
-  sed -i -E "s# (New[a-zA-Z0-9_]*Client\\()# ${pkg}.\\1#g" "${gwfile}"
-  sed -i -E "s|go.etcd.io/etcd|go.etcd.io/etcd/v3|g" "${gwfile}"
-  sed -i -E "s|go.etcd.io/etcd/v3/api|go.etcd.io/etcd/api/v3|g" "${gwfile}"
-  sed -i -E "s|go.etcd.io/etcd/v3/server|go.etcd.io/etcd/server/v3|g" "${gwfile}"
+  run sed -i -E "s#package $pkg#package gw#g" "${gwfile}"
+  run sed -i -E "s#import \\(#import \\(\"go.etcd.io/etcd/${pkgpath}\"#g" "${gwfile}"
+  run sed -i -E "s#([ (])([a-zA-Z0-9_]*(Client|Server|Request)([^(]|$))#\\1${pkg}.\\2#g" "${gwfile}"
+  run sed -i -E "s# (New[a-zA-Z0-9_]*Client\\()# ${pkg}.\\1#g" "${gwfile}"
+  run sed -i -E "s|go.etcd.io/etcd|go.etcd.io/etcd/v3|g" "${gwfile}"
+  run sed -i -E "s|go.etcd.io/etcd/v3/api|go.etcd.io/etcd/api/v3|g" "${gwfile}"
+  run sed -i -E "s|go.etcd.io/etcd/v3/server|go.etcd.io/etcd/server/v3|g" "${gwfile}"
  
  run go fmt "${gwfile}"

--- a/server/etcdserver/storage.go
+++ b/server/etcdserver/storage.go
@ -54,8 +54,9 @@ func NewStorage(w *wal.WAL, s *snap.Snapshotter) Storage {
 // SaveSnap saves the snapshot file to disk and writes the WAL snapshot entry.
 func (st *storage) SaveSnap(snap raftpb.Snapshot) error {
 	walsnap := walpb.Snapshot{
-		Index: snap.Metadata.Index,
-		Term:  snap.Metadata.Term,
+		Index:     snap.Metadata.Index,
+		Term:      snap.Metadata.Term,
+		ConfState: &snap.Metadata.ConfState,
 	}
 	// save the snapshot file before writing the snapshot to the wal.
 	// This makes it possible for the snapshot file to become orphaned, but prevents
--- a/server/wal/wal.go
+++ b/server/wal/wal.go
@ -608,7 +608,6 @@ func ValidSnapshotEntries(lg *zap.Logger, walDir string) ([]walpb.Snapshot, erro
 		}
 	}
 	snaps = snaps[:n:n]
-
 	return snaps, nil
 }

@ -944,6 +943,10 @@ func (w *WAL) Save(st raftpb.HardState, ents []raftpb.Entry) error {
 }

 func (w *WAL) SaveSnapshot(e walpb.Snapshot) error {
+	if err := walpb.ValidateSnapshotForWrite(&e); err != nil {
+		return err
+	}
+
 	b := pbutil.MustMarshal(&e)

 	w.mu.Lock()
--- a/server/wal/wal_test.go
+++ b/server/wal/wal_test.go
@ -35,8 +35,15 @@ import (
 	"go.uber.org/zap"
 )

+var (
+	confState = raftpb.ConfState{
+		Voters:    []uint64{0x00ffca74},
+		AutoLeave: false,
+	}
+)
+
 func TestNew(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -90,7 +97,7 @@ func TestNew(t *testing.T) {
 }

 func TestCreateFailFromPollutedDir(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -104,7 +111,7 @@ func TestCreateFailFromPollutedDir(t *testing.T) {
 }

 func TestWalCleanup(t *testing.T) {
-	testRoot, err := ioutil.TempDir(os.TempDir(), "waltestroot")
+	testRoot, err := ioutil.TempDir(t.TempDir(), "waltestroot")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -135,7 +142,7 @@ func TestWalCleanup(t *testing.T) {
 }

 func TestCreateFailFromNoSpaceLeft(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -154,7 +161,7 @@ func TestCreateFailFromNoSpaceLeft(t *testing.T) {
 }

 func TestNewForInitedDir(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -167,7 +174,7 @@ func TestNewForInitedDir(t *testing.T) {
 }

 func TestOpenAtIndex(t *testing.T) {
-	dir, err := ioutil.TempDir(os.TempDir(), "waltest")
+	dir, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -210,7 +217,7 @@ func TestOpenAtIndex(t *testing.T) {
 	}
 	w.Close()

-	emptydir, err := ioutil.TempDir(os.TempDir(), "waltestempty")
+	emptydir, err := ioutil.TempDir(t.TempDir(), "waltestempty")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -224,7 +231,7 @@ 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) {
-	walDir, err := ioutil.TempDir(os.TempDir(), "waltest")
+	walDir, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -273,7 +280,7 @@ func TestVerify(t *testing.T) {

 // TODO: split it into smaller tests for better readability
 func TestCut(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -304,7 +311,7 @@ func TestCut(t *testing.T) {
 	if err = w.cut(); err != nil {
 		t.Fatal(err)
 	}
-	snap := walpb.Snapshot{Index: 2, Term: 1}
+	snap := walpb.Snapshot{Index: 2, Term: 1, ConfState: &confState}
 	if err = w.SaveSnapshot(snap); err != nil {
 		t.Fatal(err)
 	}
@ -335,7 +342,7 @@ func TestCut(t *testing.T) {
 }

 func TestSaveWithCut(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -398,7 +405,7 @@ func TestSaveWithCut(t *testing.T) {
 }

 func TestRecover(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -513,7 +520,7 @@ func TestScanWalName(t *testing.T) {
 }

 func TestRecoverAfterCut(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -524,7 +531,7 @@ func TestRecoverAfterCut(t *testing.T) {
 		t.Fatal(err)
 	}
 	for i := 0; i < 10; i++ {
-		if err = md.SaveSnapshot(walpb.Snapshot{Index: uint64(i)}); err != nil {
+		if err = md.SaveSnapshot(walpb.Snapshot{Index: uint64(i), Term: 1, ConfState: &confState}); err != nil {
 			t.Fatal(err)
 		}
 		es := []raftpb.Entry{{Index: uint64(i)}}
@ -542,7 +549,7 @@ func TestRecoverAfterCut(t *testing.T) {
 	}

 	for i := 0; i < 10; i++ {
-		w, err := Open(zap.NewExample(), p, walpb.Snapshot{Index: uint64(i)})
+		w, err := Open(zap.NewExample(), p, walpb.Snapshot{Index: uint64(i), Term: 1})
 		if err != nil {
 			if i <= 4 {
 				if err != ErrFileNotFound {
@ -571,7 +578,7 @@ func TestRecoverAfterCut(t *testing.T) {
 }

 func TestOpenAtUncommittedIndex(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -605,7 +612,7 @@ func TestOpenAtUncommittedIndex(t *testing.T) {
 // it releases the lock of part of data, and excepts that OpenForRead
 // can read out all files even if some are locked for write.
 func TestOpenForRead(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -646,7 +653,7 @@ func TestOpenForRead(t *testing.T) {
 }

 func TestOpenWithMaxIndex(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -689,7 +696,7 @@ func TestSaveEmpty(t *testing.T) {
 }

 func TestReleaseLockTo(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -761,7 +768,7 @@ func TestReleaseLockTo(t *testing.T) {

 // TestTailWriteNoSlackSpace ensures that tail writes append if there's no preallocated space.
 func TestTailWriteNoSlackSpace(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -827,7 +834,7 @@ func TestTailWriteNoSlackSpace(t *testing.T) {

 // TestRestartCreateWal ensures that an interrupted WAL initialization is clobbered on restart
 func TestRestartCreateWal(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -867,7 +874,7 @@ func TestOpenOnTornWrite(t *testing.T) {
 	clobberIdx := 20
 	overwriteEntries := 5

-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -952,7 +959,7 @@ func TestOpenOnTornWrite(t *testing.T) {
 }

 func TestRenameFail(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -964,7 +971,7 @@ func TestRenameFail(t *testing.T) {
 	}()
 	SegmentSizeBytes = math.MaxInt64

-	tp, terr := ioutil.TempDir(os.TempDir(), "waltest")
+	tp, terr := ioutil.TempDir(t.TempDir(), "waltest")
 	if terr != nil {
 		t.Fatal(terr)
 	}
@ -982,7 +989,7 @@ func TestRenameFail(t *testing.T) {

 // TestReadAllFail ensure ReadAll error if used without opening the WAL
 func TestReadAllFail(t *testing.T) {
-	dir, err := ioutil.TempDir(os.TempDir(), "waltest")
+	dir, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
@ -1004,18 +1011,18 @@ func TestReadAllFail(t *testing.T) {
 // TestValidSnapshotEntries ensures ValidSnapshotEntries returns all valid wal snapshot entries, accounting
 // for hardstate
 func TestValidSnapshotEntries(t *testing.T) {
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(p)
-	snap0 := walpb.Snapshot{Index: 0, Term: 0}
-	snap1 := walpb.Snapshot{Index: 1, Term: 1}
+	snap0 := walpb.Snapshot{}
+	snap1 := walpb.Snapshot{Index: 1, Term: 1, ConfState: &confState}
 	state1 := raftpb.HardState{Commit: 1, Term: 1}
-	snap2 := walpb.Snapshot{Index: 2, Term: 1}
-	snap3 := walpb.Snapshot{Index: 3, Term: 2}
+	snap2 := walpb.Snapshot{Index: 2, Term: 1, ConfState: &confState}
+	snap3 := walpb.Snapshot{Index: 3, Term: 2, ConfState: &confState}
 	state2 := raftpb.HardState{Commit: 3, Term: 2}
-	snap4 := walpb.Snapshot{Index: 4, Term: 2} // will be orphaned since the last committed entry will be snap3
+	snap4 := walpb.Snapshot{Index: 4, Term: 2, ConfState: &confState} // will be orphaned since the last committed entry will be snap3
 	func() {
 		w, err := Create(zap.NewExample(), p, nil)
 		if err != nil {
@ -1061,16 +1068,16 @@ func TestValidSnapshotEntriesAfterPurgeWal(t *testing.T) {
 	defer func() {
 		SegmentSizeBytes = oldSegmentSizeBytes
 	}()
-	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	p, err := ioutil.TempDir(t.TempDir(), "waltest")
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(p)
-	snap0 := walpb.Snapshot{Index: 0, Term: 0}
-	snap1 := walpb.Snapshot{Index: 1, Term: 1}
+	snap0 := walpb.Snapshot{}
+	snap1 := walpb.Snapshot{Index: 1, Term: 1, ConfState: &confState}
 	state1 := raftpb.HardState{Commit: 1, Term: 1}
-	snap2 := walpb.Snapshot{Index: 2, Term: 1}
-	snap3 := walpb.Snapshot{Index: 3, Term: 2}
+	snap2 := walpb.Snapshot{Index: 2, Term: 1, ConfState: &confState}
+	snap3 := walpb.Snapshot{Index: 3, Term: 2, ConfState: &confState}
 	state2 := raftpb.HardState{Commit: 3, Term: 2}
 	func() {
 		w, err := Create(zap.NewExample(), p, nil)
--- a/server/wal/walpb/record.go
+++ b/server/wal/walpb/record.go
@ -27,3 +27,15 @@ func (rec *Record) Validate(crc uint32) error {
 	rec.Reset()
 	return ErrCRCMismatch
 }
+
+// ValidateSnapshotForWrite ensures the Snapshot the newly written snapshot is valid.
+//
+// There might exist log-entries written by old etcd versions that does not conform
+// to the requirements.
+func ValidateSnapshotForWrite(e *Snapshot) error {
+	// Since etcd>=3.5.0
+	if e.ConfState == nil && e.Index > 0 {
+		return errors.New("Saved (not-initial) snapshot is missing ConfState: " + e.String())
+	}
+	return nil
+}
--- a/server/wal/walpb/record.pb.go
+++ b/server/wal/walpb/record.pb.go
@ -11,6 +11,7 @@ import (

 	_ "github.com/gogo/protobuf/gogoproto"
 	proto "github.com/golang/protobuf/proto"
+	raftpb "go.etcd.io/etcd/raft/v3/raftpb"
 )

 // Reference imports to suppress errors if they are not otherwise used.
@ -66,12 +67,15 @@ func (m *Record) XXX_DiscardUnknown() {

 var xxx_messageInfo_Record proto.InternalMessageInfo

+// Keep in sync with raftpb.SnapshotMetadata.
 type Snapshot struct {
-	Index                uint64   `protobuf:"varint,1,opt,name=index" json:"index"`
-	Term                 uint64   `protobuf:"varint,2,opt,name=term" json:"term"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
-	XXX_unrecognized     []byte   `json:"-"`
-	XXX_sizecache        int32    `json:"-"`
+	Index uint64 `protobuf:"varint,1,opt,name=index" json:"index"`
+	Term  uint64 `protobuf:"varint,2,opt,name=term" json:"term"`
+	// Field populated since >=etcd-3.5.0.
+	ConfState            *raftpb.ConfState `protobuf:"bytes,3,opt,name=conf_state,json=confState" json:"conf_state,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}          `json:"-"`
+	XXX_unrecognized     []byte            `json:"-"`
+	XXX_sizecache        int32             `json:"-"`
 }

 func (m *Snapshot) Reset()         { *m = Snapshot{} }
@ -115,19 +119,22 @@ func init() {
 func init() { proto.RegisterFile("record.proto", fileDescriptor_bf94fd919e302a1d) }

 var fileDescriptor_bf94fd919e302a1d = []byte{
-	// 186 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0xe2, 0x29, 0x4a, 0x4d, 0xce,
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-	0x62, 0x49, 0xa2, 0x04, 0xb3, 0x02, 0xa3, 0x06, 0x4f, 0x10, 0x98, 0xad, 0xe4, 0xc0, 0xc5, 0x11,
-	0x9c, 0x97, 0x58, 0x50, 0x9c, 0x91, 0x5f, 0x22, 0x24, 0xc5, 0xc5, 0x9a, 0x99, 0x97, 0x92, 0x5a,
-	0x01, 0x36, 0x92, 0x05, 0xaa, 0x13, 0x22, 0x04, 0xb6, 0x2d, 0xb5, 0x28, 0x17, 0x6c, 0x28, 0x0b,
-	0xdc, 0xb6, 0xd4, 0xa2, 0x5c, 0x27, 0x91, 0x13, 0x0f, 0xe5, 0x18, 0x4e, 0x3c, 0x92, 0x63, 0xbc,
-	0xf0, 0x48, 0x8e, 0xf1, 0xc1, 0x23, 0x39, 0xc6, 0x19, 0x8f, 0xe5, 0x18, 0x00, 0x01, 0x00, 0x00,
-	0xff, 0xff, 0x7f, 0x5e, 0x5c, 0x46, 0xd3, 0x00, 0x00, 0x00,
+	// 234 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x3c, 0x8e, 0x41, 0x4e, 0xc3, 0x30,
+	0x10, 0x45, 0x63, 0xe2, 0x22, 0x18, 0xca, 0x02, 0xab, 0xaa, 0xa2, 0x2c, 0x4c, 0xd4, 0x55, 0x56,
+	0x29, 0xe2, 0x08, 0x65, 0xcf, 0x22, 0x3d, 0x00, 0x72, 0x1d, 0xa7, 0x20, 0xd1, 0x8c, 0x35, 0xb5,
+	0x04, 0xdc, 0x84, 0x23, 0x65, 0xc9, 0x09, 0x10, 0x84, 0x8b, 0xa0, 0x8c, 0x03, 0x1b, 0xfb, 0xeb,
+	0x7d, 0xf9, 0x7d, 0xc3, 0x9c, 0x9c, 0x45, 0x6a, 0x2a, 0x4f, 0x18, 0x50, 0xcd, 0x5e, 0xcc, 0xb3,
+	0xdf, 0xe5, 0x8b, 0x3d, 0xee, 0x91, 0xc9, 0x7a, 0x4c, 0xb1, 0xcc, 0x97, 0x64, 0xda, 0xb0, 0x1e,
+	0x0f, 0xbf, 0xe3, 0x2b, 0xf2, 0xd5, 0x3d, 0x9c, 0xd6, 0x2c, 0x51, 0x19, 0xc8, 0xf0, 0xe6, 0x5d,
+	0x26, 0x0a, 0x51, 0xa6, 0x1b, 0xd9, 0x7f, 0x5e, 0x27, 0x35, 0x13, 0xb5, 0x84, 0xd4, 0x92, 0xcd,
+	0x4e, 0x0a, 0x51, 0x5e, 0x4e, 0xc5, 0x08, 0x94, 0x02, 0xd9, 0x98, 0x60, 0xb2, 0xb4, 0x10, 0xe5,
+	0xbc, 0xe6, 0xbc, 0x22, 0x38, 0xdb, 0x76, 0xc6, 0x1f, 0x1f, 0x31, 0xa8, 0x1c, 0x66, 0x4f, 0x5d,
+	0xe3, 0x5e, 0x59, 0x29, 0xa7, 0x97, 0x11, 0xf1, 0x9a, 0xa3, 0x03, 0x4b, 0xe5, 0xff, 0x9a, 0xa3,
+	0x83, 0xba, 0x01, 0xb0, 0xd8, 0xb5, 0x0f, 0xc7, 0x60, 0x82, 0x63, 0xf7, 0xc5, 0xed, 0x55, 0x15,
+	0x7f, 0x5e, 0xdd, 0x61, 0xd7, 0x6e, 0xc7, 0xa2, 0x3e, 0xb7, 0x7f, 0x71, 0xb3, 0xe8, 0xbf, 0x75,
+	0xd2, 0x0f, 0x5a, 0x7c, 0x0c, 0x5a, 0x7c, 0x0d, 0x5a, 0xbc, 0xff, 0xe8, 0xe4, 0x37, 0x00, 0x00,
+	0xff, 0xff, 0xc3, 0x36, 0x0c, 0xad, 0x1d, 0x01, 0x00, 0x00,
 }

 func (m *Record) Marshal() (dAtA []byte, err error) {
@ -194,6 +201,18 @@ func (m *Snapshot) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 		i -= len(m.XXX_unrecognized)
 		copy(dAtA[i:], m.XXX_unrecognized)
 	}
+	if m.ConfState != nil {
+		{
+			size, err := m.ConfState.MarshalToSizedBuffer(dAtA[:i])
+			if err != nil {
+				return 0, err
+			}
+			i -= size
+			i = encodeVarintRecord(dAtA, i, uint64(size))
+		}
+		i--
+		dAtA[i] = 0x1a
+	}
 	i = encodeVarintRecord(dAtA, i, uint64(m.Term))
 	i--
 	dAtA[i] = 0x10
@ -240,6 +259,10 @@ func (m *Snapshot) Size() (n int) {
 	_ = l
 	n += 1 + sovRecord(uint64(m.Index))
 	n += 1 + sovRecord(uint64(m.Term))
+	if m.ConfState != nil {
+		l = m.ConfState.Size()
+		n += 1 + l + sovRecord(uint64(l))
+	}
 	if m.XXX_unrecognized != nil {
 		n += len(m.XXX_unrecognized)
 	}
@ -442,6 +465,42 @@ func (m *Snapshot) Unmarshal(dAtA []byte) error {
 					break
 				}
 			}
+		case 3:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field ConfState", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowRecord
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthRecord
+			}
+			postIndex := iNdEx + msglen
+			if postIndex < 0 {
+				return ErrInvalidLengthRecord
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.ConfState == nil {
+				m.ConfState = &raftpb.ConfState{}
+			}
+			if err := m.ConfState.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
 		default:
 			iNdEx = preIndex
 			skippy, err := skipRecord(dAtA[iNdEx:])
--- a/server/wal/walpb/record.proto
+++ b/server/wal/walpb/record.proto
@ -2,6 +2,7 @@ syntax = "proto2";
 package walpb;

 import "gogoproto/gogo.proto";
+import "raft/raftpb/raft.proto";

 option (gogoproto.marshaler_all) = true;
 option (gogoproto.sizer_all) = true;
@ -14,7 +15,10 @@ message Record {
 	optional bytes data  = 3;
 }

+// Keep in sync with raftpb.SnapshotMetadata.
 message Snapshot {
 	optional uint64 index = 1 [(gogoproto.nullable) = false];
 	optional uint64 term  = 2 [(gogoproto.nullable) = false];
+	// Field populated since >=etcd-3.5.0.
+	optional raftpb.ConfState conf_state = 3;
 }
--- a/server/wal/walpb/record_test.go
+++ b/server/wal/walpb/record_test.go
@ -0,0 +1,36 @@
+package walpb
+
+import (
+	"testing"
+
+	"github.com/golang/protobuf/descriptor"
+	"go.etcd.io/etcd/raft/v3/raftpb"
+)
+
+func TestSnapshotMetadataCompatibility(t *testing.T) {
+	_, snapshotMetadataMd := descriptor.ForMessage(&raftpb.SnapshotMetadata{})
+	_, snapshotMd := descriptor.ForMessage(&Snapshot{})
+	if len(snapshotMetadataMd.GetField()) != len(snapshotMd.GetField()) {
+		t.Errorf("Different number of fields in raftpb.SnapshotMetadata vs. walpb.Snapshot. " +
+			"They are supposed to be in sync.")
+	}
+}
+
+func TestValidateSnapshot(t *testing.T) {
+	tests := []struct {
+		name    string
+		snap    *Snapshot
+		wantErr bool
+	}{
+		{name: "empty", snap: &Snapshot{}, wantErr: false},
+		{name: "invalid", snap: &Snapshot{Index: 5, Term: 3}, wantErr: true},
+		{name: "valid", snap: &Snapshot{Index: 5, Term: 3, ConfState: &raftpb.ConfState{Voters: []uint64{0x00cad1}}}, wantErr: false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if err := ValidateSnapshotForWrite(tt.snap); (err != nil) != tt.wantErr {
+				t.Errorf("ValidateSnapshotForWrite() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}