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backup.go
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backup.go
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package backup
import (
"encoding/binary"
"encoding/json"
"errors"
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"path/filepath"
"strconv"
"strings"
"time"
"github.com/influxdb/influxdb/services/snapshotter"
"github.com/influxdb/influxdb/tcp"
)
const (
// Suffix is a suffix added to the backup while it's in-process.
Suffix = ".pending"
// Metafile is the base name given to the metastore backups.
Metafile = "meta"
// BackupFilePattern is the beginning of the pattern for a backup
// file. They follow the scheme <database>.<retention>.<shardID>.<increment>
BackupFilePattern = "%s.%s.%05d"
)
// Command represents the program execution for "influxd backup".
type Command struct {
// The logger passed to the ticker during execution.
Logger *log.Logger
// Standard input/output, overridden for testing.
Stderr io.Writer
Stdout io.Writer
host string
path string
database string
}
// NewCommand returns a new instance of Command with default settings.
func NewCommand() *Command {
return &Command{
Stderr: os.Stderr,
Stdout: os.Stdout,
}
}
// Run executes the program.
func (cmd *Command) Run(args ...string) error {
// Set up logger.
cmd.Logger = log.New(cmd.Stderr, "", log.LstdFlags)
// Parse command line arguments.
retentionPolicy, shardID, since, err := cmd.parseFlags(args)
if err != nil {
return err
}
// based on the arguments passed in we only backup the minimum
if shardID != "" {
// always backup the metastore
if err := cmd.backupMetastore(); err != nil {
return err
}
err = cmd.backupShard(retentionPolicy, shardID, since)
} else if retentionPolicy != "" {
err = cmd.backupRetentionPolicy(retentionPolicy, since)
} else if cmd.database != "" {
err = cmd.backupDatabase(since)
} else {
err = cmd.backupMetastore()
}
if err != nil {
cmd.Logger.Printf("backup failed: %v", err)
return err
}
cmd.Logger.Println("backup complete")
return nil
}
// parseFlags parses and validates the command line arguments into a request object.
func (cmd *Command) parseFlags(args []string) (retentionPolicy, shardID string, since time.Time, err error) {
fs := flag.NewFlagSet("", flag.ContinueOnError)
fs.StringVar(&cmd.host, "host", "localhost:8088", "")
fs.StringVar(&cmd.database, "database", "", "")
fs.StringVar(&retentionPolicy, "retention", "", "")
fs.StringVar(&shardID, "shard", "", "")
var sinceArg string
fs.StringVar(&sinceArg, "since", "", "")
fs.SetOutput(cmd.Stderr)
fs.Usage = cmd.printUsage
err = fs.Parse(args)
if err != nil {
return
}
if sinceArg != "" {
since, err = time.Parse(time.RFC3339, sinceArg)
if err != nil {
return
}
}
// Ensure that only one arg is specified.
if fs.NArg() == 0 {
return "", "", time.Unix(0, 0), errors.New("backup destination path required")
} else if fs.NArg() != 1 {
return "", "", time.Unix(0, 0), errors.New("only one backup path allowed")
}
cmd.path = fs.Arg(0)
err = os.MkdirAll(cmd.path, 0700)
return
}
// backupShard will write a tar archive of the passed in shard with any TSM files that have been
// created since the time passed in
func (cmd *Command) backupShard(retentionPolicy string, shardID string, since time.Time) error {
id, err := strconv.ParseUint(shardID, 10, 64)
if err != nil {
return err
}
shardArchivePath, err := cmd.nextPath(filepath.Join(cmd.path, fmt.Sprintf(BackupFilePattern, cmd.database, retentionPolicy, id)))
if err != nil {
return err
}
cmd.Logger.Printf("backing up db=%v rp=%v shard=%v to %s since %s",
cmd.database, retentionPolicy, shardID, shardArchivePath, since)
req := &snapshotter.Request{
Type: snapshotter.RequestShardBackup,
Database: cmd.database,
RetentionPolicy: retentionPolicy,
ShardID: id,
Since: since,
}
// TODO: verify shard backup data
return cmd.downloadAndVerify(req, shardArchivePath, nil)
}
// backupDatabase will request the database information from the server and then backup the metastore and
// every shard in every retention policy in the database. Each shard will be written to a separate tar.
func (cmd *Command) backupDatabase(since time.Time) error {
cmd.Logger.Printf("backing up db=%s since %s", cmd.database, since)
req := &snapshotter.Request{
Type: snapshotter.RequestDatabaseInfo,
Database: cmd.database,
}
response, err := cmd.requestInfo(req)
if err != nil {
return err
}
return cmd.backupResponsePaths(response, since)
}
// backupRetentionPolicy will request the retention policy information from the server and then backup
// the metastore and every shard in the retention policy. Each shard will be written to a separate tar.
func (cmd *Command) backupRetentionPolicy(retentionPolicy string, since time.Time) error {
cmd.Logger.Printf("backing up rp=%s since %s", retentionPolicy, since)
req := &snapshotter.Request{
Type: snapshotter.RequestRetentionPolicyInfo,
Database: cmd.database,
RetentionPolicy: retentionPolicy,
}
response, err := cmd.requestInfo(req)
if err != nil {
return err
}
return cmd.backupResponsePaths(response, since)
}
// backupResponsePaths will backup the metastore and all shard paths in the response struct
func (cmd *Command) backupResponsePaths(response *snapshotter.Response, since time.Time) error {
if err := cmd.backupMetastore(); err != nil {
return err
}
// loop through the returned paths and back up each shard
for _, path := range response.Paths {
rp, id, err := retentionAndShardFromPath(path)
if err != nil {
return err
}
if err := cmd.backupShard(rp, id, since); err != nil {
return err
}
}
return nil
}
// backupMetastore will backup the metastore on the host to the passed in path. Database and retention policy backups
// will force a backup of the metastore as well as requesting a specific shard backup from the command line
func (cmd *Command) backupMetastore() error {
metastoreArchivePath, err := cmd.nextPath(filepath.Join(cmd.path, Metafile))
if err != nil {
return err
}
cmd.Logger.Printf("backing up metastore to %s", metastoreArchivePath)
req := &snapshotter.Request{
Type: snapshotter.RequestMetastoreBackup,
}
return cmd.downloadAndVerify(req, metastoreArchivePath, func(file string) error {
binData, err := ioutil.ReadFile(file)
if err != nil {
return err
}
magic := btou64(binData[:8])
if magic != snapshotter.BackupMagicHeader {
cmd.Logger.Println("Invalid metadata blob, ensure the metadata service is running (default port 8088)")
return errors.New("invalid metadata received")
}
return nil
})
}
// nextPath returns the next file to write to.
func (cmd *Command) nextPath(path string) (string, error) {
// Iterate through incremental files until one is available.
for i := 0; ; i++ {
s := fmt.Sprintf(path+".%02d", i)
if _, err := os.Stat(s); os.IsNotExist(err) {
return s, nil
} else if err != nil {
return "", err
}
}
}
// downloadAndVerify will download either the metastore or shard to a temp file and then
// rename it to a good backup file name after complete
func (cmd *Command) downloadAndVerify(req *snapshotter.Request, path string, validator func(string) error) error {
tmppath := path + Suffix
if err := cmd.download(req, tmppath); err != nil {
return err
}
if validator != nil {
if err := validator(tmppath); err != nil {
if rmErr := os.Remove(tmppath); rmErr != nil {
cmd.Logger.Printf("Error cleaning up temporary file: %v", rmErr)
}
return err
}
}
// Rename temporary file to final path.
if err := os.Rename(tmppath, path); err != nil {
return fmt.Errorf("rename: %s", err)
}
return nil
}
// download downloads a snapshot of either the metastore or a shard from a host to a given path.
func (cmd *Command) download(req *snapshotter.Request, path string) error {
// Create local file to write to.
f, err := os.Create(path)
if err != nil {
return fmt.Errorf("open temp file: %s", err)
}
defer f.Close()
// Connect to snapshotter service.
conn, err := tcp.Dial("tcp", cmd.host, snapshotter.MuxHeader)
if err != nil {
return err
}
defer conn.Close()
// Write the request
if err := json.NewEncoder(conn).Encode(req); err != nil {
return fmt.Errorf("encode snapshot request: %s", err)
}
// Read snapshot from the connection
if _, err := io.Copy(f, conn); err != nil {
return fmt.Errorf("copy backup to file: %s", err)
}
return nil
}
// requestInfo will request the database or retention policy information from the host
func (cmd *Command) requestInfo(request *snapshotter.Request) (*snapshotter.Response, error) {
// Connect to snapshotter service.
conn, err := tcp.Dial("tcp", cmd.host, snapshotter.MuxHeader)
if err != nil {
return nil, err
}
defer conn.Close()
// Write the request
if err := json.NewEncoder(conn).Encode(request); err != nil {
return nil, fmt.Errorf("encode snapshot request: %s", err)
}
// Read the response
var r snapshotter.Response
if err := json.NewDecoder(conn).Decode(&r); err != nil {
return nil, err
}
return &r, nil
}
// printUsage prints the usage message to STDERR.
func (cmd *Command) printUsage() {
fmt.Fprintf(cmd.Stdout, `usage: influxd backup [flags] PATH
Backup downloads a snapshot of a data node and saves it to disk.
Options:
-host <host:port>
The host to connect to snapshot. Defaults to 127.0.0.1:8088.
-database <name>
The database to backup.
-retention <name>
Optional. The retention policy to backup.
-shard <id>
Optional. The shard id to backup. If specified, retention is required.
-since <2015-12-24T08:12:23>
Optional. Do an incremental backup since the passed in RFC3339
formatted time.
`)
}
// retentionAndShardFromPath will take the shard relative path and split it into the
// retention policy name and shard ID. The first part of the path should be the database name.
func retentionAndShardFromPath(path string) (retention, shard string, err error) {
a := strings.Split(path, "/")
if len(a) != 3 {
return "", "", fmt.Errorf("expected database, retention policy, and shard id in path: %s", path)
}
return a[1], a[2], nil
}
func btou64(b []byte) uint64 {
return binary.BigEndian.Uint64(b)
}