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litestream/cmd/litestream/restore.go
2020-12-31 10:36:48 -07:00

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package main
import (
"context"
"errors"
"flag"
"fmt"
"log"
"os"
"path/filepath"
"time"
"github.com/benbjohnson/litestream"
)
type RestoreCommand struct {
}
func (c *RestoreCommand) Run(ctx context.Context, args []string) (err error) {
var configPath string
opt := litestream.NewRestoreOptions()
fs := flag.NewFlagSet("litestream-restore", flag.ContinueOnError)
registerConfigFlag(fs, &configPath)
fs.StringVar(&opt.OutputPath, "o", "", "output path")
fs.StringVar(&opt.ReplicaName, "replica", "", "replica name")
fs.StringVar(&opt.Generation, "generation", "", "generation name")
fs.IntVar(&opt.Index, "index", opt.Index, "wal index")
fs.BoolVar(&opt.DryRun, "dry-run", false, "dry run")
timestampStr := fs.String("timestamp", "", "timestamp")
verbose := fs.Bool("v", false, "verbose output")
fs.Usage = c.Usage
if err := fs.Parse(args); err != nil {
return err
} else if fs.NArg() == 0 || fs.Arg(0) == "" {
return fmt.Errorf("database path required")
} else if fs.NArg() > 1 {
return fmt.Errorf("too many arguments")
}
// Load configuration.
if configPath == "" {
return errors.New("-config required")
}
config, err := ReadConfigFile(configPath)
if err != nil {
return err
}
// Parse timestamp, if specified.
if *timestampStr != "" {
if opt.Timestamp, err = time.Parse(time.RFC3339, *timestampStr); err != nil {
return errors.New("invalid -timestamp, must specify in ISO 8601 format (e.g. 2000-01-01T00:00:00Z)")
}
}
// Verbose output is automatically enabled if dry run is specified.
if opt.DryRun {
*verbose = true
}
// Instantiate logger if verbose output is enabled.
if *verbose {
opt.Logger = log.New(os.Stderr, "", log.LstdFlags)
}
// Determine absolute path for database.
dbPath, err := filepath.Abs(fs.Arg(0))
if err != nil {
return err
}
// Instantiate DB.
dbConfig := config.DBConfig(dbPath)
if dbConfig == nil {
return fmt.Errorf("database not found in config: %s", dbPath)
}
db, err := newDBFromConfig(dbConfig)
if err != nil {
return err
}
return db.Restore(ctx, opt)
}
func (c *RestoreCommand) Usage() {
fmt.Printf(`
The restore command recovers a database from a previous snapshot and WAL.
Usage:
litestream restore [arguments] DB
Arguments:
-config PATH
Specifies the configuration file.
Defaults to %s
-replica NAME
Restore from a specific replica.
Defaults to replica with latest data.
-generation NAME
Restore from a specific generation.
Defaults to generation with latest data.
-index NUM
Restore up to a specific WAL index (inclusive).
Defaults to use the highest available index.
-timestamp TIMESTAMP
Restore to a specific point-in-time.
Defaults to use the latest available backup.
-o PATH
Output path of the restored database.
Defaults to original DB path.
-dry-run
Prints all log output as if it were running but does
not perform actual restore.
-v
Verbose output.
Examples:
# Restore latest replica for database to original location.
$ litestream restore /path/to/db
# Restore replica for database to a given point in time.
$ litestream restore -timestamp 2020-01-01T00:00:00Z /path/to/db
# Restore latest replica for database to new /tmp directory
$ litestream restore -o /tmp/db /path/to/db
# Restore database from latest generation on S3.
$ litestream restore -replica s3 /path/to/db
# Restore database from specific generation on S3.
$ litestream restore -replica s3 -generation xxxxxxxx /path/to/db
`[1:],
DefaultConfigPath,
)
}