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backup_command.go
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backup_command.go
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// Copyright 2021 The etcd 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 etcdutl
import (
"os"
"path"
"regexp"
"time"
"github.com/spf13/cobra"
"go.etcd.io/etcd/api/v3/etcdserverpb"
"go.etcd.io/etcd/client/pkg/v3/fileutil"
"go.etcd.io/etcd/client/pkg/v3/types"
"go.etcd.io/etcd/pkg/v3/idutil"
"go.etcd.io/etcd/pkg/v3/pbutil"
"go.etcd.io/etcd/raft/v3/raftpb"
"go.etcd.io/etcd/server/v3/etcdserver/api/membership"
"go.etcd.io/etcd/server/v3/etcdserver/api/snap"
"go.etcd.io/etcd/server/v3/etcdserver/api/v2store"
"go.etcd.io/etcd/server/v3/storage/backend"
"go.etcd.io/etcd/server/v3/storage/datadir"
"go.etcd.io/etcd/server/v3/storage/schema"
"go.etcd.io/etcd/server/v3/storage/wal"
"go.etcd.io/etcd/server/v3/storage/wal/walpb"
"go.etcd.io/etcd/server/v3/verify"
bolt "go.etcd.io/bbolt"
"go.uber.org/zap"
)
var (
withV3 bool
dataDir string
backupDir string
walDir string
backupWalDir string
)
func NewBackupCommand() *cobra.Command {
cmd := &cobra.Command{
Use: "backup",
Short: "[legacy] offline backup of etcd directory",
Long: "Prefer: `etcdctl snapshot save` instead.",
Run: doBackup,
}
cmd.Flags().StringVar(&dataDir, "data-dir", "", "Path to the etcd data dir")
cmd.Flags().StringVar(&walDir, "wal-dir", "", "Path to the etcd wal dir")
cmd.Flags().StringVar(&backupDir, "backup-dir", "", "Path to the backup dir")
cmd.Flags().StringVar(&backupWalDir, "backup-wal-dir", "", "Path to the backup wal dir")
cmd.Flags().BoolVar(&withV3, "with-v3", true, "Backup v3 backend data")
cmd.MarkFlagRequired("data-dir")
cmd.MarkFlagRequired("backup-dir")
cmd.MarkFlagDirname("data-dir")
cmd.MarkFlagDirname("wal-dir")
cmd.MarkFlagDirname("backup-dir")
cmd.MarkFlagDirname("backup-wal-dir")
return cmd
}
func doBackup(cmd *cobra.Command, args []string) {
HandleBackup(withV3, dataDir, backupDir, walDir, backupWalDir)
}
type desiredCluster struct {
clusterId types.ID
nodeId types.ID
members []*membership.Member
confState raftpb.ConfState
}
func newDesiredCluster() desiredCluster {
idgen := idutil.NewGenerator(0, time.Now())
nodeID := idgen.Next()
clusterID := idgen.Next()
return desiredCluster{
clusterId: types.ID(clusterID),
nodeId: types.ID(nodeID),
members: []*membership.Member{
{
ID: types.ID(nodeID),
Attributes: membership.Attributes{
Name: "etcdctl-v2-backup",
},
RaftAttributes: membership.RaftAttributes{
PeerURLs: []string{"http://use-flag--force-new-cluster:2080"},
}}},
confState: raftpb.ConfState{Voters: []uint64{nodeID}},
}
}
// HandleBackup handles a request that intends to do a backup.
func HandleBackup(withV3 bool, srcDir string, destDir string, srcWAL string, destWAL string) error {
lg := GetLogger()
srcSnap := datadir.ToSnapDir(srcDir)
destSnap := datadir.ToSnapDir(destDir)
if srcWAL == "" {
srcWAL = datadir.ToWalDir(srcDir)
}
if destWAL == "" {
destWAL = datadir.ToWalDir(destDir)
}
if err := fileutil.CreateDirAll(lg, destSnap); err != nil {
lg.Fatal("failed creating backup snapshot dir", zap.String("dest-snap", destSnap), zap.Error(err))
}
destDbPath := datadir.ToBackendFileName(destDir)
srcDbPath := datadir.ToBackendFileName(srcDir)
desired := newDesiredCluster()
walsnap := saveSnap(lg, destSnap, srcSnap, &desired)
metadata, state, ents := translateWAL(lg, srcWAL, walsnap, withV3)
saveDB(lg, destDbPath, srcDbPath, state.Commit, state.Term, &desired, withV3)
neww, err := wal.Create(lg, destWAL, pbutil.MustMarshal(&metadata))
if err != nil {
lg.Fatal("wal.Create failed", zap.Error(err))
}
defer neww.Close()
if err := neww.Save(state, ents); err != nil {
lg.Fatal("wal.Save failed ", zap.Error(err))
}
if err := neww.SaveSnapshot(walsnap); err != nil {
lg.Fatal("SaveSnapshot", zap.Error(err))
}
verify.MustVerifyIfEnabled(verify.Config{
Logger: lg,
DataDir: destDir,
ExactIndex: false,
})
return nil
}
func saveSnap(lg *zap.Logger, destSnap, srcSnap string, desired *desiredCluster) (walsnap walpb.Snapshot) {
ss := snap.New(lg, srcSnap)
snapshot, err := ss.Load()
if err != nil && err != snap.ErrNoSnapshot {
lg.Fatal("saveSnap(Snapshoter.Load) failed", zap.Error(err))
}
if snapshot != nil {
walsnap.Index, walsnap.Term, walsnap.ConfState = snapshot.Metadata.Index, snapshot.Metadata.Term, &desired.confState
newss := snap.New(lg, destSnap)
snapshot.Metadata.ConfState = desired.confState
snapshot.Data = mustTranslateV2store(lg, snapshot.Data, desired)
if err = newss.SaveSnap(*snapshot); err != nil {
lg.Fatal("saveSnap(Snapshoter.SaveSnap) failed", zap.Error(err))
}
}
return walsnap
}
// mustTranslateV2store processes storeData such that they match 'desiredCluster'.
// In particular the method overrides membership information.
func mustTranslateV2store(lg *zap.Logger, storeData []byte, desired *desiredCluster) []byte {
st := v2store.New()
if err := st.Recovery(storeData); err != nil {
lg.Panic("cannot translate v2store", zap.Error(err))
}
raftCluster := membership.NewClusterFromMembers(lg, desired.clusterId, desired.members)
raftCluster.SetID(desired.nodeId, desired.clusterId)
raftCluster.SetStore(st)
raftCluster.PushMembershipToStorage()
outputData, err := st.Save()
if err != nil {
lg.Panic("cannot save v2store", zap.Error(err))
}
return outputData
}
func translateWAL(lg *zap.Logger, srcWAL string, walsnap walpb.Snapshot, v3 bool) (etcdserverpb.Metadata, raftpb.HardState, []raftpb.Entry) {
w, err := wal.OpenForRead(lg, srcWAL, walsnap)
if err != nil {
lg.Fatal("wal.OpenForRead failed", zap.Error(err))
}
defer w.Close()
wmetadata, state, ents, err := w.ReadAll()
switch err {
case nil:
case wal.ErrSnapshotNotFound:
lg.Warn("failed to find the match snapshot record", zap.Any("walsnap", walsnap), zap.String("srcWAL", srcWAL))
lg.Warn("etcdctl will add it back. Start auto fixing...")
default:
lg.Fatal("unexpected error while reading WAL", zap.Error(err))
}
re := path.Join(membership.StoreMembersPrefix, "[[:xdigit:]]{1,16}", "attributes")
memberAttrRE := regexp.MustCompile(re)
for i := 0; i < len(ents); i++ {
// Replacing WAL entries with 'dummy' entries allows to avoid
// complicated entries shifting and risk of other data (like consistent_index)
// running out of sync.
// Also moving entries and computing offsets would get complicated if
// TERM changes (so there are superflous entries from previous term).
if ents[i].Type == raftpb.EntryConfChange {
lg.Info("ignoring EntryConfChange raft entry")
raftEntryToNoOp(&ents[i])
continue
}
var raftReq etcdserverpb.InternalRaftRequest
var v2Req *etcdserverpb.Request
if pbutil.MaybeUnmarshal(&raftReq, ents[i].Data) {
v2Req = raftReq.V2
} else {
v2Req = &etcdserverpb.Request{}
pbutil.MustUnmarshal(v2Req, ents[i].Data)
}
if v2Req != nil && v2Req.Method == "PUT" && memberAttrRE.MatchString(v2Req.Path) {
lg.Info("ignoring member attribute update on",
zap.Stringer("entry", &ents[i]),
zap.String("v2Req.Path", v2Req.Path))
raftEntryToNoOp(&ents[i])
continue
}
if v2Req != nil {
lg.Debug("preserving log entry", zap.Stringer("entry", &ents[i]))
}
if raftReq.ClusterMemberAttrSet != nil {
lg.Info("ignoring cluster_member_attr_set")
raftEntryToNoOp(&ents[i])
continue
}
if v3 || raftReq.Header == nil {
lg.Debug("preserving log entry", zap.Stringer("entry", &ents[i]))
continue
}
lg.Info("ignoring v3 raft entry")
raftEntryToNoOp(&ents[i])
}
var metadata etcdserverpb.Metadata
pbutil.MustUnmarshal(&metadata, wmetadata)
return metadata, state, ents
}
func raftEntryToNoOp(entry *raftpb.Entry) {
// Empty (dummy) entries are send by RAFT when new leader is getting elected.
// They do not cary any change to data-model so its safe to replace entries
// to be ignored with them.
*entry = raftpb.Entry{Term: entry.Term, Index: entry.Index, Type: raftpb.EntryNormal, Data: nil}
}
// saveDB copies the v3 backend and strips cluster information.
func saveDB(lg *zap.Logger, destDB, srcDB string, idx uint64, term uint64, desired *desiredCluster, v3 bool) {
// open src db to safely copy db state
if v3 {
var src *bolt.DB
ch := make(chan *bolt.DB, 1)
go func() {
db, err := bolt.Open(srcDB, 0444, &bolt.Options{ReadOnly: true})
if err != nil {
lg.Fatal("bolt.Open FAILED", zap.Error(err))
}
ch <- db
}()
select {
case src = <-ch:
case <-time.After(time.Second):
lg.Fatal("timed out waiting to acquire lock on", zap.String("srcDB", srcDB))
}
defer src.Close()
tx, err := src.Begin(false)
if err != nil {
lg.Fatal("bbolt.BeginTx failed", zap.Error(err))
}
// copy srcDB to destDB
dest, err := os.Create(destDB)
if err != nil {
lg.Fatal("creation of destination file failed", zap.String("dest", destDB), zap.Error(err))
}
if _, err := tx.WriteTo(dest); err != nil {
lg.Fatal("bbolt write to destination file failed", zap.String("dest", destDB), zap.Error(err))
}
dest.Close()
if err := tx.Rollback(); err != nil {
lg.Fatal("bbolt tx.Rollback failed", zap.String("dest", destDB), zap.Error(err))
}
}
be := backend.NewDefaultBackend(lg, destDB)
defer be.Close()
ms := schema.NewMembershipBackend(lg, be)
if err := ms.TrimClusterFromBackend(); err != nil {
lg.Fatal("bbolt tx.Membership failed", zap.Error(err))
}
raftCluster := membership.NewClusterFromMembers(lg, desired.clusterId, desired.members)
raftCluster.SetID(desired.nodeId, desired.clusterId)
raftCluster.SetBackend(ms)
raftCluster.PushMembershipToStorage()
if !v3 {
tx := be.BatchTx()
tx.LockOutsideApply()
defer tx.Unlock()
schema.UnsafeCreateMetaBucket(tx)
schema.UnsafeUpdateConsistentIndex(tx, idx, term, false)
} else {
// Thanks to translateWAL not moving entries, but just replacing them with
// 'empty', there is no need to update the consistency index.
}
}