cli: prepare the restart config the same way as start

cmd/restart.go

@@ -1,9 +1,11 @@
 package cmd
 
 import (
+	"fmt"
 	"time"
 
 	"github.com/abiosoft/colima/cmd/root"
+	"github.com/abiosoft/colima/config"
 	"github.com/abiosoft/colima/config/configmanager"
 	"github.com/abiosoft/colima/environment/vm/lima/limautil"
 	"github.com/spf13/cobra"
@@ -28,6 +30,14 @@ should return it back to its previous state.`,
 			return err
 		}
 
+		conf, err := restartConfig()
+		if err != nil {
+			return err
+		}
+		if err := configmanager.ValidateConfig(conf); err != nil {
+			return fmt.Errorf("error in config: %w", err)
+		}
+
 		app := newApp()
 
 		if err := app.Stop(restartCmdArgs.force); err != nil {
@@ -37,15 +47,26 @@ should return it back to its previous state.`,
 		// delay a bit before starting
 		time.Sleep(time.Second * 3)
 
-		config, err := configmanager.Load()
-		if err != nil {
-			return err
-		}
-
-		return app.Start(config)
+		return app.Start(conf)
 	},
 }
 
+func restartConfig() (config.Config, error) {
+	current, err := configmanager.Load()
+	if err != nil {
+		return config.Config{}, err
+	}
+	// prepareConfig would ignore it and use plain defaults, which can grow the data disk
+	if current.Empty() {
+		return configmanager.LoadInstance()
+	}
+	prepareConfig(startCmd)
+	if startCmdArgs.DiskImage == "" && current.DiskImage != "" {
+		startCmdArgs.DiskImage = current.DiskImage
+	}
+	return startCmdArgs.Config, nil
+}
+
 func init() {
 	root.Cmd().AddCommand(restartCmd)
 

cmd/restart_test.go

@@ -0,0 +1,96 @@
+package cmd
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/abiosoft/colima/config"
+)
+
+func TestMain(m *testing.M) {
+	// config dirs are cached on first use, so point them at a temp dir before any test runs
+	home, err := os.MkdirTemp("", "colima-test")
+	if err != nil {
+		panic(err)
+	}
+	_ = os.Setenv("COLIMA_HOME", home)
+	_ = os.Unsetenv("LIMA_HOME")
+	code := m.Run()
+	_ = os.RemoveAll(home)
+	os.Exit(code)
+}
+
+func Test_restartConfig(t *testing.T) {
+	home := os.Getenv("COLIMA_HOME")
+	config.SetProfile("restart-test")
+
+	file := config.CurrentProfile().File()
+	stateFile := config.CurrentProfile().StateFile()
+	if !strings.HasPrefix(file, home) || !strings.HasPrefix(stateFile, home) {
+		t.Fatalf("config files %s and %s are outside COLIMA_HOME %s", file, stateFile, home)
+	}
+
+	write := func(t *testing.T, path, content string) {
+		t.Helper()
+		if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(path, []byte(content), 0644); err != nil {
+			t.Fatal(err)
+		}
+		t.Cleanup(func() { _ = os.Remove(path) })
+	}
+
+	t.Run("partial config gets start defaults", func(t *testing.T) {
+		write(t, file, "cpu: 3\ndisk: 30\nruntime: containerd\n")
+
+		conf, err := restartConfig()
+		if err != nil {
+			t.Fatalf("restartConfig() error = %v", err)
+		}
+		if conf.CPU != 3 || conf.Disk != 30 || conf.Runtime != "containerd" {
+			t.Errorf("restartConfig() did not keep file values: cpu=%d disk=%d runtime=%q", conf.CPU, conf.Disk, conf.Runtime)
+		}
+		if conf.RootDisk != defaultRootDisk {
+			t.Errorf("restartConfig() RootDisk = %d, want %d", conf.RootDisk, defaultRootDisk)
+		}
+		if conf.Binfmt == nil || !*conf.Binfmt {
+			t.Errorf("restartConfig() Binfmt = %v, want true", conf.Binfmt)
+		}
+	})
+
+	t.Run("missing config uses the instance state", func(t *testing.T) {
+		write(t, stateFile, "cpu: 4\ndisk: 60\nruntime: containerd\n")
+
+		conf, err := restartConfig()
+		if err != nil {
+			t.Fatalf("restartConfig() error = %v", err)
+		}
+		if conf.CPU != 4 || conf.Disk != 60 || conf.Runtime != "containerd" {
+			t.Errorf("restartConfig() did not use the instance state: cpu=%d disk=%d runtime=%q", conf.CPU, conf.Disk, conf.Runtime)
+		}
+	})
+
+	t.Run("preserves saved custom disk image", func(t *testing.T) {
+		write(t, file, "cpu: 2\ndisk: 20\nruntime: docker\ndiskImage: /path/to/custom.img\n")
+
+		conf, err := restartConfig()
+		if err != nil {
+			t.Fatalf("restartConfig() error = %v", err)
+		}
+		if conf.DiskImage != "/path/to/custom.img" {
+			t.Errorf("restartConfig() DiskImage = %q, want %q", conf.DiskImage, "/path/to/custom.img")
+		}
+	})
+
+	t.Run("unreadable config is an error", func(t *testing.T) {
+		write(t, stateFile, "cpu: 4\ndisk: 60\nruntime: containerd\n")
+		write(t, file, "cpu: [\n")
+
+		if _, err := restartConfig(); err == nil {
+			t.Error("restartConfig() error = nil, want an error")
+		}
+	})
+}