support `--untar` flag for dep update

Signed-off-by: Weiping Cai <weiping.cai@daocloud.io>

cmd/helm/dependency_update.go

@@ -17,12 +17,14 @@ package main
 
 import (
 	"io"
+	"os"
 	"path/filepath"
 
 	"github.com/spf13/cobra"
 
 	"helm.sh/helm/v3/cmd/helm/require"
 	"helm.sh/helm/v3/pkg/action"
+	"helm.sh/helm/v3/pkg/chartutil"
 	"helm.sh/helm/v3/pkg/downloader"
 	"helm.sh/helm/v3/pkg/getter"
 )
@@ -71,13 +73,31 @@ func newDependencyUpdateCmd(cfg *action.Configuration, out io.Writer) *cobra.Com
 			if client.Verify {
 				man.Verify = downloader.VerifyAlways
 			}
-			return man.Update()
+
+			err := man.Update()
+			if err != nil {
+				return err
+			}
+
+			if client.Untar {
+				match := chartpath + "/charts/*.tgz"
+				files, err := filepath.Glob(match)
+				if err != nil {
+					return err
+				}
+				for _, f := range files {
+					chartutil.ExpandFile(chartpath+"/charts/", f)
+					os.Remove(f)
+				}
+			}
+			return nil
 		},
 	}
 
 	f := cmd.Flags()
 	f.BoolVar(&client.Verify, "verify", false, "verify the packages against signatures")
 	f.StringVar(&client.Keyring, "keyring", defaultKeyring(), "keyring containing public keys")
+	f.BoolVar(&client.Untar, "untar", false, "if set to true, will untar the chart after downloading it")
 	f.BoolVar(&client.SkipRefresh, "skip-refresh", false, "do not refresh the local repository cache")
 
 	return cmd

cmd/helm/dependency_update_test.go

@@ -148,6 +148,18 @@ func TestDependencyUpdateCmd(t *testing.T) {
 	if _, err := os.Stat(expect); err != nil {
 		t.Fatal(err)
 	}
+	// when use `--untar` flag, ./charts/*.tgz should not existed.
+	_, _, err = executeActionCommand(
+		fmt.Sprintf("dependency update '%s' --repository-config %s --repository-cache %s --untar", dir(chartname), dir("repositories.yaml"), dir()),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Make sure the actual file got downloaded,and untar it.
+	expect = dir(chartname, "charts/reqtest")
+	if _, err := os.Stat(expect); err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestDependencyUpdateCmd_DontDeleteOldChartsOnError(t *testing.T) {

pkg/action/dependency.go

@@ -35,6 +35,7 @@ import (
 // It provides the implementation of 'helm dependency' and its respective subcommands.
 type Dependency struct {
 	Verify      bool
+	Untar       bool
 	Keyring     string
 	SkipRefresh bool
 }