added more user-friendly validation messages.

cmd/policygen/config.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"github.com/go-playground/validator/v10"
 	"github.com/goccy/go-yaml"
 	"log"
 	"net"
@@ -95,8 +94,13 @@ func (c *Config) Update(config *Config) {
 }
 
 func (c Config) ValidateSchema() error {
-	validate := validator.New(validator.WithRequiredStructEnabled())
-	return validate.Struct(c)
+
+	validator, err := NewValidator()
+	if err != nil {
+		return err
+	}
+	err = validator.ValidateStruct(c)
+	return err
 }
 
 func (c Config) Validate() error {

cmd/policygen/validator.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"github.com/go-playground/locales/en"
+	ut "github.com/go-playground/universal-translator"
+	"github.com/go-playground/validator/v10"
+	en_translations "github.com/go-playground/validator/v10/translations/en"
+)
+
+type Validator struct {
+	validate *validator.Validate
+	trans    ut.Translator
+}
+
+type Translation struct {
+	format string
+	params func(fe validator.FieldError) []any
+}
+
+var translations = map[string]Translation{
+	"oneof": {
+		"{0} must be one of [{1}], got '{2}'",
+		func(fe validator.FieldError) []any {
+			return []any{fe.Field(), fe.Param(), fe.Value()}
+		},
+	},
+}
+
+func NewValidator() (*Validator, error) {
+	validate := validator.New(validator.WithRequiredStructEnabled())
+	language := en.New()
+	translator := ut.New(language, language)
+	trans, ok := translator.GetTranslator("en")
+	if !ok {
+		return nil, fmt.Errorf("Could not find translator to print error meesage")
+	}
+	en_translations.RegisterDefaultTranslations(validate, trans)
+
+	for validation, translation := range translations {
+		validate.RegisterTranslation(validation, trans,
+			func(ut ut.Translator) error {
+				return ut.Add(validation, translation.format, true)
+			},
+			func(ut ut.Translator, fe validator.FieldError) string {
+				params := translation.params(fe)
+				stringParams := make([]string, len(params))
+				for i, param := range params {
+					stringParams[i] = fmt.Sprintf("%s", param)
+				}
+				t, _ := ut.T(validation, stringParams...)
+				return t
+			})
+	}
+
+	return &Validator{
+		validate: validate,
+		trans:    trans,
+	}, nil
+}
+
+func (v Validator) ValidateStruct(s interface{}) error {
+	err := v.validate.Struct(s)
+	return v.Translate(err)
+}
+
+func (v Validator) Translate(err error) error {
+	if err == nil {
+		return err
+	}
+	errs, ok := err.(validator.ValidationErrors)
+	if !ok {
+		return err
+	}
+
+	errorList := make([]error, 0)
+	for _, e := range errs {
+		errorList = append(errorList, fmt.Errorf("%s", e.Translate(v.trans)))
+	}
+	return errors.Join(errorList...)
+}

example/config.yaml

@@ -10,13 +10,14 @@ networks:
       - 192.168.0.0/16
     ports:
       - port: 2303
+        protocol: UDP
 
 
 namespaces:
   - name: wamblee-org
     #open: true
     capabilities:
-      - linkerdd
+      - linkerd
       - dns
     applications:
       - name: nexus-server