Add WithValidator option to producer API

Signed-off-by: Evan Lezar <elezar@nvidia.com>

Author: elezar

pkg/cdi/producer/save.go

@@ -30,6 +30,10 @@ import (
 	cdi "tags.cncf.io/container-device-interface/specs-go"
 )
 
+type validator interface {
+	Validate(*cdi.Spec) error
+}
+
 type options struct {
 	outputFormat string
 	validator    validator
@@ -106,6 +110,10 @@ func Save(raw *cdi.Spec, path string, opts ...Option) error {
 func WriteTo(raw *cdi.Spec, w io.Writer, opts ...Option) (int64, error) {
 	o := populateOptions(opts...)
 
+	if err := o.Validate(raw); err != nil {
+		return 0, fmt.Errorf("spec validation failed: %w", err)
+	}
+
 	data, err := o.marshal(raw)
 	if err != nil {
 		return 0, fmt.Errorf("failed to marshal spec: %w", err)
@@ -243,3 +251,21 @@ func (o *options) marshal(v any) ([]byte, error) {
 		return nil, fmt.Errorf("invalid output format: %q", o.outputFormat)
 	}
 }
+
+// Validate a CDI specification using the supplied options.
+// If no validator is specified, validation always succeeds.
+func (o *options) Validate(raw *cdi.Spec) error {
+	if o == nil || o.validator == nil {
+		return nil
+	}
+	return o.validator.Validate(raw)
+}
+
+type validatorFunction func(*cdi.Spec) error
+
+func (v validatorFunction) Validate(raw *cdi.Spec) error {
+	if v == nil {
+		return nil
+	}
+	return v(raw)
+}

pkg/cdi/producer/save_test.go

@@ -17,6 +17,7 @@
 package producer
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -141,6 +142,21 @@ devices: []
 				require.EqualValues(t, expectedContents, string(contents))
 			},
 		},
+		{
+			description: "validator is called before save",
+			spec: &cdi.Spec{
+				Version: "v1.1.0",
+			},
+			filename: "test.yaml",
+			options: []Option{
+				WithValidator(validatorFunction(func(s *cdi.Spec) error { return fmt.Errorf("invalid spec") })),
+				WithPermissions(os.FileMode(0666)),
+			},
+			expectedError: "failed to write Spec file: spec validation failed: invalid spec",
+			assert: func(t *testing.T, fullpath string) {
+				require.NoFileExists(t, fullpath)
+			},
+		},
 	}
 
 	for _, tc := range testCases {

pkg/cdi/spec.go

@@ -113,21 +113,13 @@ func newSpec(raw *cdi.Spec, path string, priority int) (*Spec, error) {
 // Write the CDI Spec to the file associated with it during instantiation
 // by newSpec() or ReadSpec().
 func (s *Spec) write(overwrite bool) error {
-	var (
-		err error
-	)
-
-	err = validateSpec(s.Spec)
-	if err != nil {
-		return err
-	}
-
 	return producer.Save(s.Spec, s.path,
 		// If we cannot determine the file format as yaml from the extension,
 		// we assume a json format.
 		producer.WithOutputFormat("json"),
 		producer.WithOverwrite(overwrite),
 		producer.WithPermissions(0),
+		producer.WithValidatorFunction(validateSpec),
 	)
 }