tar: read directly from stdin

pkg/buildcontext/tar.go

@@ -17,10 +17,9 @@ limitations under the License.
 package buildcontext
 
 import (
+	"compress/gzip"
 	"fmt"
-	"io/ioutil"
 	"os"
-	"path/filepath"
 
 	"github.com/GoogleContainerTools/kaniko/pkg/constants"
 	"github.com/GoogleContainerTools/kaniko/pkg/util"
@@ -47,14 +46,15 @@ func (t *Tar) UnpackTarFromBuildContext() (string, error) {
 		logrus.Infof("To simulate EOF and exit, press 'Ctrl+D'")
 		// if launched through docker in interactive mode and without piped data
 		// process will be stuck here until EOF is sent
-		data, err := util.GetInputFrom(os.Stdin)
+		gzr, err := gzip.NewReader(os.Stdin)
 		if err != nil {
-			return "", errors.Wrap(err, "fail to get standard input")
-		}
-		t.context = filepath.Join(directory, constants.ContextTar)
-		if err := ioutil.WriteFile(t.context, data, 0644); err != nil {
-			return "", errors.Wrap(err, "fail to redirect standard input into compressed tar file")
+			return directory, err
 		}
+		defer gzr.Close()
+		_, err = util.UnTar(gzr, directory)
+
+		return directory, err
+
 	}
 
 	return directory, util.UnpackCompressedTar(t.context, directory)

pkg/util/fs_util.go

@@ -261,8 +261,8 @@ func childDirInIgnoreList(path string) bool {
 	return false
 }
 
-// unTar returns a list of files that have been extracted from the tar archive at r to the path at dest
-func unTar(r io.Reader, dest string) ([]string, error) {
+// UnTar returns a list of files that have been extracted from the tar archive at r to the path at dest
+func UnTar(r io.Reader, dest string) ([]string, error) {
 	var extractedFiles []string
 	tr := tar.NewReader(r)
 	for {

pkg/util/fs_util_test.go

@@ -626,7 +626,7 @@ func createUncompressedTar(fileContents map[string]string, tarFileName, testDir
 	return nil
 }
 
-func Test_unTar(t *testing.T) {
+func Test_UnTar(t *testing.T) {
 	tcs := []struct {
 		name             string
 		setupTarContents map[string]string
@@ -671,7 +671,7 @@ func Test_unTar(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			fileList, err := unTar(file, tc.destination)
+			fileList, err := UnTar(file, tc.destination)
 			if err != nil {
 				t.Fatal(err)
 			}

pkg/util/tar_util.go

@@ -218,7 +218,7 @@ func UnpackLocalTarArchive(path, dest string) ([]string, error) {
 			return nil, UnpackCompressedTar(path, dest)
 		} else if compressionLevel == archive.Bzip2 {
 			bzr := bzip2.NewReader(file)
-			return unTar(bzr, dest)
+			return UnTar(bzr, dest)
 		}
 	}
 	if fileIsUncompressedTar(path) {
@@ -227,7 +227,7 @@ func UnpackLocalTarArchive(path, dest string) ([]string, error) {
 			return nil, err
 		}
 		defer file.Close()
-		return unTar(file, dest)
+		return UnTar(file, dest)
 	}
 	return nil, errors.New("path does not lead to local tar archive")
 }
@@ -286,6 +286,6 @@ func UnpackCompressedTar(path, dir string) error {
 		return err
 	}
 	defer gzr.Close()
-	_, err = unTar(gzr, dir)
+	_, err = UnTar(gzr, dir)
 	return err
 }