wings/server/backup/archiver.go

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package backup
import (
"archive/tar"
"context"
"emperror.dev/errors"
"github.com/apex/log"
"github.com/juju/ratelimit"
gzip "github.com/klauspost/pgzip"
"github.com/pterodactyl/wings/config"
"github.com/remeh/sizedwaitgroup"
"golang.org/x/sync/errgroup"
"io"
"os"
"runtime"
"strings"
"sync"
)
type Archive struct {
sync.Mutex
TrimPrefix string
Files *IncludedFiles
}
// Creates an archive at dst with all of the files defined in the included files struct.
func (a *Archive) Create(dst string, ctx context.Context) error {
f, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return err
}
defer f.Close()
// Select a writer based off of the WriteLimit configuration option.
var writer io.Writer
if writeLimit := config.Get().System.Backups.WriteLimit; writeLimit < 1 {
// If there is no write limit, use the file as the writer.
writer = f
} else {
// Token bucket with a capacity of "writeLimit" MiB, adding "writeLimit" MiB/s
bucket := ratelimit.NewBucketWithRate(float64(writeLimit)*1024*1024, int64(writeLimit)*1024*1024)
// Wrap the file writer with the token bucket limiter.
writer = ratelimit.Writer(f, bucket)
}
maxCpu := runtime.NumCPU() / 2
if maxCpu > 4 {
maxCpu = 4
}
gzw, err := gzip.NewWriterLevel(writer, gzip.BestSpeed)
if err != nil {
return errors.WithMessage(err, "failed to create gzip writer")
}
if err := gzw.SetConcurrency(1<<20, maxCpu); err != nil {
return errors.WithMessage(err, "failed to set gzip concurrency")
}
defer gzw.Flush()
defer gzw.Close()
tw := tar.NewWriter(gzw)
defer tw.Flush()
defer tw.Close()
wg := sizedwaitgroup.New(10)
g, ctx := errgroup.WithContext(ctx)
// Iterate over all of the files to be included and put them into the archive. This is
// done as a concurrent goroutine to speed things along. If an error is encountered at
// any step, the entire process is aborted.
for _, p := range a.Files.All() {
p := p
g.Go(func() error {
wg.Add()
defer wg.Done()
select {
case <-ctx.Done():
return ctx.Err()
default:
return a.addToArchive(p, tw)
}
})
}
// Block until the entire routine is completed.
if err := g.Wait(); err != nil {
f.Close()
// Attempt to remove the archive if there is an error, report that error to
// the logger if it fails.
if rerr := os.Remove(dst); rerr != nil && !os.IsNotExist(rerr) {
log.WithField("location", dst).Warn("failed to delete corrupted backup archive")
}
return err
}
return nil
}
// Adds a single file to the existing tar archive writer.
func (a *Archive) addToArchive(p string, w *tar.Writer) error {
f, err := os.Open(p)
if err != nil {
// If you try to backup something that no longer exists (got deleted somewhere during the process
// but not by this process), just skip over it and don't kill the entire backup.
if os.IsNotExist(err) {
return nil
}
return err
}
defer f.Close()
s, err := f.Stat()
if err != nil {
// Same as above, don't kill the process just because the file no longer exists.
if os.IsNotExist(err) {
return nil
}
return err
}
name := strings.TrimPrefix(p, a.TrimPrefix)
header, err := tar.FileInfoHeader(s, name)
if err != nil {
return errors.WithMessage(err, "failed to get tar#FileInfoHeader for "+name)
}
header.Name = name
// These actions must occur sequentially, even if this function is called multiple
// in parallel. You'll get some nasty panic's otherwise.
a.Lock()
defer a.Unlock()
if err := w.WriteHeader(header); err != nil {
return err
}
buf := make([]byte, 4*1024)
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if _, err := io.CopyBuffer(w, io.LimitReader(f, header.Size), buf); err != nil {
return errors.WithMessage(err, "failed to copy "+header.Name+" to archive")
}
return nil
}