unify the validation rules on initializer name

staging/src/k8s.io/apimachinery/pkg/api/validation/objectmeta.go

@@ -195,9 +195,7 @@ func ValidateInitializers(initializers *metav1.Initializers, fldPath *field.Path
 		return allErrs
 	}
 	for i, initializer := range initializers.Pending {
-		for _, msg := range validation.IsQualifiedName(initializer.Name) {
-			allErrs = append(allErrs, field.Invalid(fldPath.Child("pending").Index(i), initializer.Name, msg))
-		}
+		allErrs = append(allErrs, validation.IsFullyQualifiedName(fldPath.Child("pending").Index(i).Child("name"), initializer.Name)...)
 	}
 	allErrs = append(allErrs, validateInitializersResult(initializers.Result, fldPath.Child("result"))...)
 	return allErrs

staging/src/k8s.io/apimachinery/pkg/util/validation/BUILD

@@ -10,11 +10,13 @@ go_test(
     name = "go_default_test",
     srcs = ["validation_test.go"],
     library = ":go_default_library",
+    deps = ["//vendor/k8s.io/apimachinery/pkg/util/validation/field:go_default_library"],
 )
 
 go_library(
     name = "go_default_library",
     srcs = ["validation.go"],
+    deps = ["//vendor/k8s.io/apimachinery/pkg/util/validation/field:go_default_library"],
 )
 
 filegroup(

staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go

@@ -22,6 +22,8 @@ import (
 	"net"
 	"regexp"
 	"strings"
+
+	"k8s.io/apimachinery/pkg/util/validation/field"
 )
 
 const qnameCharFmt string = "[A-Za-z0-9]"
@@ -67,6 +69,21 @@ func IsQualifiedName(value string) []string {
 	return errs
 }
 
+// IsFullyQualifiedName checks if the name is fully qualified.
+func IsFullyQualifiedName(fldPath *field.Path, name string) field.ErrorList {
+	var allErrors field.ErrorList
+	if len(name) == 0 {
+		return append(allErrors, field.Required(fldPath, ""))
+	}
+	if errs := IsDNS1123Subdomain(name); len(errs) > 0 {
+		return append(allErrors, field.Invalid(fldPath, name, strings.Join(errs, ",")))
+	}
+	if len(strings.Split(name, ".")) < 3 {
+		return append(allErrors, field.Invalid(fldPath, name, "should be a domain with at least three segments separated by dots"))
+	}
+	return allErrors
+}
+
 const labelValueFmt string = "(" + qualifiedNameFmt + ")?"
 const labelValueErrMsg string = "a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character"
 const LabelValueMaxLength int = 63

staging/src/k8s.io/apimachinery/pkg/util/validation/validation_test.go

@@ -19,6 +19,8 @@ package validation
 import (
 	"strings"
 	"testing"
+
+	"k8s.io/apimachinery/pkg/util/validation/field"
 )
 
 func TestIsDNS1123Label(t *testing.T) {
@@ -450,3 +452,38 @@ func TestIsWildcardDNS1123Subdomain(t *testing.T) {
 		}
 	}
 }
+
+func TestIsFullyQualifiedName(t *testing.T) {
+	tests := []struct {
+		name       string
+		targetName string
+		err        string
+	}{
+		{
+			name:       "name needs to be fully qualified, i.e., contains at least 2 dots",
+			targetName: "k8s.io",
+			err:        "should be a domain with at least three segments separated by dots",
+		},
+		{
+			name:       "name cannot be empty",
+			targetName: "",
+			err:        "Required value",
+		},
+		{
+			name:       "name must conform to RFC 1123",
+			targetName: "A.B.C",
+			err:        "a DNS-1123 subdomain must consist of lower case alphanumeric characters",
+		},
+	}
+	for _, tc := range tests {
+		err := IsFullyQualifiedName(field.NewPath(""), tc.targetName).ToAggregate()
+		switch {
+		case tc.err == "" && err != nil:
+			t.Errorf("%q: unexpected error: %v", tc.name, err)
+		case tc.err != "" && err == nil:
+			t.Errorf("%q: unexpected no error, expected %s", tc.name, tc.err)
+		case tc.err != "" && err != nil && !strings.Contains(err.Error(), tc.err):
+			t.Errorf("%q: expected %s, got %v", tc.name, tc.err, err)
+		}
+	}
+}