Add Ark version to backup-version file in backup tarball

Signed-off-by: Wayne Witzel III <wayne@riotousliving.com>

pkg/backup/backup.go

@@ -32,6 +32,7 @@ import (
 	kuberrs "k8s.io/apimachinery/pkg/util/errors"
 
 	api "github.com/heptio/ark/pkg/apis/ark/v1"
+	"github.com/heptio/ark/pkg/buildinfo"
 	"github.com/heptio/ark/pkg/client"
 	"github.com/heptio/ark/pkg/cloudprovider"
 	"github.com/heptio/ark/pkg/discovery"
@@ -221,6 +222,10 @@ func (kb *kubernetesBackupper) Backup(logger logrus.FieldLogger, backupRequest *
 	log := logger.WithField("backup", kubeutil.NamespaceAndName(backupRequest))
 	log.Info("Starting backup")
 
+	if err := kb.writeBackupVersion(tw); err != nil {
+		return errors.WithStack(err)
+	}
+
 	backupRequest.NamespaceIncludesExcludes = getNamespaceIncludesExcludes(backupRequest.Backup)
 	log.Infof("Including namespaces: %s", backupRequest.NamespaceIncludesExcludes.IncludesString())
 	log.Infof("Excluding namespaces: %s", backupRequest.NamespaceIncludesExcludes.ExcludesString())
@@ -292,6 +297,23 @@ func (kb *kubernetesBackupper) Backup(logger logrus.FieldLogger, backupRequest *
 	return err
 }
 
+func (kb *kubernetesBackupper) writeBackupVersion(tw *tar.Writer) error {
+	hdr := &tar.Header{
+		Name:     "backup-version",
+		Size:     int64(len(buildinfo.Version)),
+		Typeflag: tar.TypeReg,
+		Mode:     0644,
+		ModTime:  time.Now(),
+	}
+	if err := tw.WriteHeader(hdr); err != nil {
+		return err
+	}
+	if _, err := tw.Write([]byte(buildinfo.Version)); err != nil {
+		return err
+	}
+	return nil
+}
+
 type tarWriter interface {
 	io.Closer
 	Write([]byte) (int, error)