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backup_command.go
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backup_command.go
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// Copyright 2015 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 command
import (
"encoding/binary"
"log"
"os"
"path"
"path/filepath"
"regexp"
"time"
"github.com/coreos/etcd/etcdserver/etcdserverpb"
"github.com/coreos/etcd/etcdserver/membership"
"github.com/coreos/etcd/pkg/fileutil"
"github.com/coreos/etcd/pkg/idutil"
"github.com/coreos/etcd/pkg/pbutil"
"github.com/coreos/etcd/raft/raftpb"
"github.com/coreos/etcd/snap"
"github.com/coreos/etcd/wal"
"github.com/coreos/etcd/wal/walpb"
bolt "github.com/coreos/bbolt"
"github.com/urfave/cli"
)
func NewBackupCommand() cli.Command {
return cli.Command{
Name: "backup",
Usage: "backup an etcd directory",
ArgsUsage: " ",
Flags: []cli.Flag{
cli.StringFlag{Name: "data-dir", Value: "", Usage: "Path to the etcd data dir"},
cli.StringFlag{Name: "wal-dir", Value: "", Usage: "Path to the etcd wal dir"},
cli.StringFlag{Name: "backup-dir", Value: "", Usage: "Path to the backup dir"},
cli.StringFlag{Name: "backup-wal-dir", Value: "", Usage: "Path to the backup wal dir"},
cli.BoolFlag{Name: "with-v3", Usage: "Backup v3 backend data"},
},
Action: handleBackup,
}
}
// handleBackup handles a request that intends to do a backup.
func handleBackup(c *cli.Context) error {
var srcWAL string
var destWAL string
withV3 := c.Bool("with-v3")
srcSnap := filepath.Join(c.String("data-dir"), "member", "snap")
destSnap := filepath.Join(c.String("backup-dir"), "member", "snap")
if c.String("wal-dir") != "" {
srcWAL = c.String("wal-dir")
} else {
srcWAL = filepath.Join(c.String("data-dir"), "member", "wal")
}
if c.String("backup-wal-dir") != "" {
destWAL = c.String("backup-wal-dir")
} else {
destWAL = filepath.Join(c.String("backup-dir"), "member", "wal")
}
if err := fileutil.CreateDirAll(destSnap); err != nil {
log.Fatalf("failed creating backup snapshot dir %v: %v", destSnap, err)
}
walsnap := saveSnap(destSnap, srcSnap)
metadata, state, ents := loadWAL(srcWAL, walsnap, withV3)
saveDB(filepath.Join(destSnap, "db"), filepath.Join(srcSnap, "db"), state.Commit, withV3)
idgen := idutil.NewGenerator(0, time.Now())
metadata.NodeID = idgen.Next()
metadata.ClusterID = idgen.Next()
neww, err := wal.Create(destWAL, pbutil.MustMarshal(&metadata))
if err != nil {
log.Fatal(err)
}
defer neww.Close()
if err := neww.Save(state, ents); err != nil {
log.Fatal(err)
}
if err := neww.SaveSnapshot(walsnap); err != nil {
log.Fatal(err)
}
return nil
}
func saveSnap(destSnap, srcSnap string) (walsnap walpb.Snapshot) {
ss := snap.New(srcSnap)
snapshot, err := ss.Load()
if err != nil && err != snap.ErrNoSnapshot {
log.Fatal(err)
}
if snapshot != nil {
walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
newss := snap.New(destSnap)
if err = newss.SaveSnap(*snapshot); err != nil {
log.Fatal(err)
}
}
return walsnap
}
func loadWAL(srcWAL string, walsnap walpb.Snapshot, v3 bool) (etcdserverpb.Metadata, raftpb.HardState, []raftpb.Entry) {
w, err := wal.OpenForRead(srcWAL, walsnap)
if err != nil {
log.Fatal(err)
}
defer w.Close()
wmetadata, state, ents, err := w.ReadAll()
switch err {
case nil:
case wal.ErrSnapshotNotFound:
log.Printf("Failed to find the match snapshot record %+v in wal %v.", walsnap, srcWAL)
log.Printf("etcdctl will add it back. Start auto fixing...")
default:
log.Fatal(err)
}
re := path.Join(membership.StoreMembersPrefix, "[[:xdigit:]]{1,16}", "attributes")
memberAttrRE := regexp.MustCompile(re)
removed := uint64(0)
i := 0
remove := func() {
ents = append(ents[:i], ents[i+1:]...)
removed++
i--
}
for i = 0; i < len(ents); i++ {
ents[i].Index -= removed
if ents[i].Type == raftpb.EntryConfChange {
log.Println("ignoring EntryConfChange raft entry")
remove()
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) {
log.Println("ignoring member attribute update on", v2Req.Path)
remove()
continue
}
if v2Req != nil {
continue
}
if v3 || raftReq.Header == nil {
continue
}
log.Println("ignoring v3 raft entry")
remove()
}
state.Commit -= removed
var metadata etcdserverpb.Metadata
pbutil.MustUnmarshal(&metadata, wmetadata)
return metadata, state, ents
}
// saveDB copies the v3 backend and strips cluster information.
func saveDB(destDB, srcDB string, idx uint64, v3 bool) {
// open src db to safely copy db state
if v3 {
var src *bolt.DB
ch := make(chan *bolt.DB, 1)
go func() {
src, err := bolt.Open(srcDB, 0444, &bolt.Options{ReadOnly: true})
if err != nil {
log.Fatal(err)
}
ch <- src
}()
select {
case src = <-ch:
case <-time.After(time.Second):
log.Println("waiting to acquire lock on", srcDB)
src = <-ch
}
defer src.Close()
tx, err := src.Begin(false)
if err != nil {
log.Fatal(err)
}
// copy srcDB to destDB
dest, err := os.Create(destDB)
if err != nil {
log.Fatal(err)
}
if _, err := tx.WriteTo(dest); err != nil {
log.Fatal(err)
}
dest.Close()
if err := tx.Rollback(); err != nil {
log.Fatal(err)
}
}
db, err := bolt.Open(destDB, 0644, &bolt.Options{})
if err != nil {
log.Fatal(err)
}
tx, err := db.Begin(true)
if err != nil {
log.Fatal(err)
}
// remove membership information; should be clobbered by --force-new-cluster
for _, bucket := range []string{"members", "members_removed", "cluster"} {
tx.DeleteBucket([]byte(bucket))
}
// update consistent index to match hard state
if !v3 {
idxBytes := make([]byte, 8)
binary.BigEndian.PutUint64(idxBytes, idx)
b, err := tx.CreateBucketIfNotExists([]byte("meta"))
if err != nil {
log.Fatal(err)
}
b.Put([]byte("consistent_index"), idxBytes)
}
if err := tx.Commit(); err != nil {
log.Fatal(err)
}
if err := db.Close(); err != nil {
log.Fatal(err)
}
}