fixed bug that caused helm create to not overwrite modified files

Signed-off-by: Matt Butcher <matt.butcher@microsoft.com>

cmd/helm/create.go

@@ -107,6 +107,7 @@ func (o *createOptions) run(out io.Writer) error {
 		return chartutil.CreateFrom(cfile, filepath.Dir(o.name), lstarter)
 	}
 
+	chartutil.Stderr = out
 	_, err := chartutil.Create(chartname, filepath.Dir(o.name))
 	return err
 }

pkg/chartutil/create.go

@@ -18,6 +18,7 @@ package chartutil
 
 import (
 	"fmt"
+	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -468,6 +469,12 @@ spec:
   restartPolicy: Never
 `
 
+// Stderr is an io.Writer to which error messages can be written
+//
+// In Helm 4, this will be replaced. It is needed in Helm 3 to preserve API backward
+// compatibility.
+var Stderr io.Writer = os.Stderr
+
 // CreateFrom creates a new chart, but scaffolds it from the src chart.
 func CreateFrom(chartfile *chart.Metadata, dest, src string) error {
 	schart, err := loader.Load(src)
@@ -601,8 +608,8 @@ func Create(name, dir string) (string, error) {
 
 	for _, file := range files {
 		if _, err := os.Stat(file.path); err == nil {
-			// File exists and is okay. Skip it.
-			continue
+			// There is no handle to a preferred output stream here.
+			fmt.Fprintf(Stderr, "WARNING: File %q already exists. Overwriting.\n", file.path)
 		}
 		if err := writeFile(file.path, file.content); err != nil {
 			return cdir, err

pkg/chartutil/create_test.go

@@ -117,3 +117,42 @@ func TestCreateFrom(t *testing.T) {
 		}
 	}
 }
+
+// TestCreate_Overwrite is a regression test for making sure that files are overwritten.
+func TestCreate_Overwrite(t *testing.T) {
+	tdir, err := ioutil.TempDir("", "helm-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tdir)
+
+	var errlog bytes.Buffer
+
+	if _, err := Create("foo", tdir); err != nil {
+		t.Fatal(err)
+	}
+
+	dir := filepath.Join(tdir, "foo")
+
+	tplname := filepath.Join(dir, "templates/hpa.yaml")
+	writeFile(tplname, []byte("FOO"))
+
+	// Now re-run the create
+	Stderr = &errlog
+	if _, err := Create("foo", tdir); err != nil {
+		t.Fatal(err)
+	}
+
+	data, err := ioutil.ReadFile(tplname)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if string(data) == "FOO" {
+		t.Fatal("File that should have been modified was not.")
+	}
+
+	if errlog.Len() == 0 {
+		t.Errorf("Expected warnings about overwriting files.")
+	}
+}