feat(lk): use tmp directory while preparing files

cmd/lk/app.go

@@ -268,21 +268,29 @@ func setupTemplate(ctx context.Context, cmd *cli.Command) error {
 
 func cloneTemplate(_ context.Context, cmd *cli.Command, url, appName string) error {
 	var cmdErr error
+
+	tempName, relocate := useTempPath(appName)
+
 	if err := spinner.New().
 		Title("Cloning template from " + url).
 		Action(func() {
-			c := exec.Command("git", "clone", "--depth=1", url, appName)
+			c := exec.Command("git", "clone", "--depth=1", url, tempName)
 			var out []byte
-			if out, cmdErr = c.CombinedOutput(); len(out) > 0 && cmd.Bool("verbose") {
-				fmt.Println(string(out))
+			if out, cmdErr = c.CombinedOutput(); len(out) > 0 {
+				if cmdErr != nil || cmd.Bool("verbose") {
+					fmt.Println(string(out))
+				}
 			}
 			os.RemoveAll(path.Join(appName, ".git"))
 		}).
 		Style(theme.Focused.Title).
 		Run(); err != nil {
 		return err
 	}
-	return cmdErr
+	if cmdErr != nil {
+		return cmdErr
+	}
+	return relocate()
 }
 
 func instantiateEnv(ctx context.Context, cmd *cli.Command, rootPath string, addlEnv *map[string]string) error {

cmd/lk/utils.go

@@ -20,10 +20,13 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math/rand"
 	"net/url"
 	"os"
+	"path"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"github.com/charmbracelet/lipgloss"
 	"github.com/charmbracelet/lipgloss/table"
@@ -153,6 +156,32 @@ func wrapWith(wrap string) func(string) string {
 	}
 }
 
+func randomID() string {
+	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	seed := rand.NewSource(time.Now().UnixNano())
+	r := rand.New(seed)
+
+	result := make([]byte, 16)
+	for i := range result {
+		result[i] = charset[r.Intn(len(charset))]
+	}
+	return string(result)
+}
+
+func useTempPath(permanentPath string) (string, func() error) {
+	tempPath := path.Join(os.TempDir(), randomID())
+	relocate := func() error {
+		if err := os.Rename(tempPath, permanentPath); err != nil {
+			// NOTE: on macOS, `os.TempDir()` points to `/var/folders/...`.
+			// Because this directory is not automatically cleaned up, we need
+			// to remove it explicitly on a failure to relocate.
+			return os.RemoveAll(tempPath)
+		}
+		return nil
+	}
+	return tempPath, relocate
+}
+
 func hashString(str string) (string, error) {
 	hash := sha256.New()
 	if _, err := hash.Write([]byte(str)); err != nil {