Use a memory filesystem to scaffold and persist the changes to disk a…

…s part of the post-run

Signed-off-by: Adrian Orive <[email protected]>

pkg/cli/cli.go

@@ -99,8 +99,8 @@ type cli struct { //nolint:maligned
 	// Root command.
 	cmd *cobra.Command
 
-	// Underlying fs
-	fs afero.Fs
+	// Underlying filesystems
+	disk, memory, fs afero.Fs
 }
 
 // New creates a new cli instance.
@@ -133,13 +133,22 @@ func New(opts ...Option) (CLI, error) {
 // newCLI creates a default cli instance and applies the provided options.
 // It is as a separate function for test purposes.
 func newCLI(opts ...Option) (*cli, error) {
+	path, err := os.Getwd()
+	if err != nil {
+		return nil, fmt.Errorf("unable to get working directory: %w", err)
+	}
+	disk := afero.NewBasePathFs(afero.NewOsFs(), path)
+	memory := afero.NewBasePathFs(afero.NewMemMapFs(), path)
+
 	// Default cli options.
 	c := &cli{
 		commandName:           "kubebuilder",
 		defaultProjectVersion: cfgv3alpha.Version,
 		defaultPlugins:        make(map[config.Version][]string),
 		plugins:               make(map[string]plugin.Plugin),
-		fs:                    afero.NewOsFs(),
+		disk:                  disk,
+		memory:                memory,
+		fs:                    afero.NewCopyOnWriteFs(disk, memory),
 	}
 
 	// Apply provided options.

pkg/cli/root.go

@@ -18,8 +18,11 @@ package cli
 
 import (
 	"fmt"
+	"io"
+	"os"
 	"strings"
 
+	"github.com/spf13/afero"
 	"github.com/spf13/cobra"
 )
 
@@ -34,9 +37,10 @@ func (c cli) newRootCmd() *cobra.Command {
 		Long: `CLI tool for building Kubernetes extensions and tools.
 `,
 		Example: c.rootExamples(),
-		RunE: func(cmd *cobra.Command, args []string) error {
+		RunE: func(cmd *cobra.Command, _ []string) error {
 			return cmd.Help()
 		},
+		PersistentPostRunE: c.persistChanges,
 	}
 
 	// Global flags for all subcommands
@@ -121,3 +125,66 @@ func (c cli) getPluginTable() string {
 
 	return strings.Join(lines, "\n")
 }
+
+func closeFile(f io.Closer) {
+	_ = f.Close()
+}
+
+// persistChanges walks the scaffolded files in memory and persist them to disk
+func (c cli) persistChanges(*cobra.Command, []string) error {
+	err := afero.Walk(c.memory, ".", func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return fmt.Errorf("error walking memory filesystem at %q: %w", path, err)
+		}
+
+		if info.IsDir() {
+			// Skip directories, creating files will create the needed directories
+			return nil
+		}
+
+		var exists bool
+		exists, err = afero.Exists(c.disk, path)
+		if err != nil {
+			return fmt.Errorf("unable to check if %q existed previously: %w", path, err)
+		}
+
+		if exists {
+			var diskInfo os.FileInfo
+			diskInfo, err = c.disk.Stat(path)
+			if err != nil {
+				return fmt.Errorf("unable to obtain info of %q: %w", path, err)
+			}
+
+			if os.SameFile(info, diskInfo) {
+				// The file was unchanged, skip it
+				return nil
+			}
+		}
+
+		var source io.ReadCloser
+		source, err = c.memory.Open(path)
+		if err != nil {
+			return fmt.Errorf("unable to read %q from memory: %w", path, err)
+		}
+		defer closeFile(source)
+
+		var sink io.WriteCloser
+		sink, err = c.disk.Create(path)
+		if err != nil {
+			return fmt.Errorf("unable to create/trucate %q file: %w", path, err)
+		}
+		defer closeFile(sink)
+
+		_, err = io.Copy(sink, source)
+		if err != nil {
+			return fmt.Errorf("unable to update %q file: %w", path, err)
+		}
+
+		return nil
+	})
+	if err != nil {
+		return fmt.Errorf("unable to persist scaffolded changes to disk: %w", err)
+	}
+
+	return nil
+}