kustomize: use FS from fluxcd/pkg

This switches to a secure FS implementation in most places, except for
where we can not make changes at this moment because it would break
behavior.

Not handled in this commit:

- Allowing the root for `manifestgen` packages to be configured.
- Allowing the user to define a working root while building locally.
- Defaulting to the secure FS implementation in
  `kustomization.MakeDefaultOptions`. Problem here is that constructing
  the secure FS could result in an error, which we can not surface
  without signature changes to the constructor func.

Signed-off-by: Hidde Beydals <hello@hidde.co>

pkg/manifestgen/install/manifests.go

@@ -26,8 +26,8 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/fluxcd/pkg/kustomize/filesys"
 	"github.com/fluxcd/pkg/untar"
-	"sigs.k8s.io/kustomize/api/filesys"
 
 	"github.com/fluxcd/flux2/pkg/manifestgen/kustomization"
 )
@@ -126,8 +126,12 @@ func build(base, output string) error {
 		return err
 	}
 
-	fs := filesys.MakeFsOnDisk()
-	if err := fs.WriteFile(output, resources); err != nil {
+	outputBase := filepath.Dir(strings.TrimSuffix(output, string(filepath.Separator)))
+	fs, err := filesys.MakeFsOnDiskSecure(outputBase)
+	if err != nil {
+		return err
+	}
+	if err = fs.WriteFile(output, resources); err != nil {
 		return err
 	}
 

pkg/manifestgen/kustomization/kustomization.go

@@ -20,20 +20,23 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 
-	"sigs.k8s.io/kustomize/api/filesys"
 	"sigs.k8s.io/kustomize/api/konfig"
 	"sigs.k8s.io/kustomize/api/krusty"
 	"sigs.k8s.io/kustomize/api/provider"
 	kustypes "sigs.k8s.io/kustomize/api/types"
 	"sigs.k8s.io/yaml"
 
+	"github.com/fluxcd/pkg/kustomize/filesys"
+
 	"github.com/fluxcd/flux2/pkg/manifestgen"
 )
 
-// Generate scans the given directory for Kubernetes manifests and creates a kustomization.yaml
-// including all discovered manifests as resources.
+// Generate scans the given directory for Kubernetes manifests and creates a
+// konfig.DefaultKustomizationFileName file, including all discovered manifests
+// as resources.
 func Generate(options Options) (*manifestgen.Manifest, error) {
 	kfile := filepath.Join(options.TargetPath, konfig.DefaultKustomizationFileName())
 	abskfile := filepath.Join(options.BaseDir, kfile)
@@ -50,7 +53,7 @@ func Generate(options Options) (*manifestgen.Manifest, error) {
 				return nil
 			}
 			if info.IsDir() {
-				// If a sub-directory contains an existing Kustomization file add the
+				// If a sub-directory contains an existing Kustomization file, add the
 				// directory as a resource and do not decent into it.
 				for _, kfilename := range konfig.RecognizedKustomizationFileNames() {
 					if options.FileSystem.Exists(filepath.Join(path, kfilename)) {
@@ -88,7 +91,9 @@ func Generate(options Options) (*manifestgen.Manifest, error) {
 		if err != nil {
 			return nil, err
 		}
-		f.Close()
+		if err = f.Close(); err != nil {
+			return nil, err
+		}
 
 		kus := kustypes.Kustomization{
 			TypeMeta: kustypes.TypeMeta{
@@ -128,20 +133,32 @@ func Generate(options Options) (*manifestgen.Manifest, error) {
 	}, nil
 }
 
+// kustomizeBuildMutex is a workaround for a concurrent map read and map write bug.
+// TODO(stefan): https://github.com/kubernetes-sigs/kustomize/issues/3659
 var kustomizeBuildMutex sync.Mutex
 
-// Build takes a Kustomize overlays and returns the resulting manifests as multi-doc YAML.
+// Build takes the path to a directory with a konfig.RecognizedKustomizationFileNames,
+// builds it, and returns the resulting manifests as multi-doc YAML.
 func Build(base string) ([]byte, error) {
-	// TODO(stefan): temporary workaround for concurrent map read and map write bug
-	// https://github.com/kubernetes-sigs/kustomize/issues/3659
 	kustomizeBuildMutex.Lock()
 	defer kustomizeBuildMutex.Unlock()
 
-	kfile := filepath.Join(base, konfig.DefaultKustomizationFileName())
+	// TODO(hidde): make this configurable to a specific root (relative to base)
+	parent := filepath.Dir(strings.TrimSuffix(base, string(filepath.Separator)))
+	fs, err := filesys.MakeFsOnDiskSecureBuild(parent)
+	if err != nil {
+		return nil, err
+	}
 
-	fs := filesys.MakeFsOnDisk()
-	if !fs.Exists(kfile) {
-		return nil, fmt.Errorf("%s not found", kfile)
+	var kfile string
+	for _, f := range konfig.RecognizedKustomizationFileNames() {
+		if kf := filepath.Join(base, f); fs.Exists(kf) {
+			kfile = kf
+			break
+		}
+	}
+	if kfile == "" {
+		return nil, fmt.Errorf("%s not found", konfig.DefaultKustomizationFileName())
 	}
 
 	// TODO(hidde): work around for a bug in kustomize causing it to

pkg/manifestgen/kustomization/options.go

@@ -25,6 +25,8 @@ type Options struct {
 }
 
 func MakeDefaultOptions() Options {
+	// TODO(hidde): switch MakeFsOnDisk to MakeFsOnDiskSecureBuild when we
+	//  break API.
 	return Options{
 		FileSystem: filesys.MakeFsOnDisk(),
 		BaseDir:    "",