Add name generation and normalize common create flows

Adds `ObjectMeta.GenerateName`, an optional string field that defines
name generation behavior if a Name is not provided.

Adds `pkg/api/rest`, which defines the default Kubernetes API pattern
for creation (and will cover update as well). Will allow registries
and REST objects to be merged by moving logic on api out of those places.

Add `pkg/api/rest/resttest`, which will be the test suite that verifies
a RESTStorage object follows the Kubernetes API conventions and begin
reducing our duplicated tests.

pkg/api/validation/validation.go

@@ -53,11 +53,24 @@ func ValidateAnnotations(annotations map[string]string, field string) errs.Valid
 }
 
 // ValidateNameFunc validates that the provided name is valid for a given resource type.
-// Not all resources have the same validation rules for names.
-type ValidateNameFunc func(name string) (bool, string)
+// Not all resources have the same validation rules for names. Prefix is true if the
+// name will have a value appended to it.
+type ValidateNameFunc func(name string, prefix bool) (bool, string)
+
+// maskTrailingDash replaces the final character of a string with a subdomain safe
+// value if is a dash.
+func maskTrailingDash(name string) string {
+	if strings.HasSuffix(name, "-") {
+		return name[:len(name)-2] + "a"
+	}
+	return name
+}
 
 // nameIsDNSSubdomain is a ValidateNameFunc for names that must be a DNS subdomain.
-func nameIsDNSSubdomain(name string) (bool, string) {
+func nameIsDNSSubdomain(name string, prefix bool) (bool, string) {
+	if prefix {
+		name = maskTrailingDash(name)
+	}
 	if util.IsDNSSubdomain(name) {
 		return true, ""
 	}
@@ -65,23 +78,36 @@ func nameIsDNSSubdomain(name string) (bool, string) {
 }
 
 // nameIsDNS952Label is a ValidateNameFunc for names that must be a DNS 952 label.
-func nameIsDNS952Label(name string) (bool, string) {
+func nameIsDNS952Label(name string, prefix bool) (bool, string) {
+	if prefix {
+		name = maskTrailingDash(name)
+	}
 	if util.IsDNS952Label(name) {
 		return true, ""
 	}
 	return false, "name must be lowercase letters, numbers, and dashes"
 }
 
-// ValidateObjectMeta validates an object's metadata.
+// ValidateObjectMeta validates an object's metadata on creation. It expects that name generation has already
+// been performed.
 func ValidateObjectMeta(meta *api.ObjectMeta, requiresNamespace bool, nameFn ValidateNameFunc) errs.ValidationErrorList {
 	allErrs := errs.ValidationErrorList{}
+
+	if len(meta.GenerateName) != 0 {
+		if ok, qualifier := nameFn(meta.GenerateName, true); !ok {
+			allErrs = append(allErrs, errs.NewFieldInvalid("generateName", meta.GenerateName, qualifier))
+		}
+	}
+	// if the generated name validates, but the calculated value does not, it's a problem with generation, and we
+	// report it here. This may confuse users, but indicates a programming bug and still must be validated.
 	if len(meta.Name) == 0 {
 		allErrs = append(allErrs, errs.NewFieldRequired("name", meta.Name))
 	} else {
-		if ok, qualifier := nameFn(meta.Name); !ok {
+		if ok, qualifier := nameFn(meta.Name, false); !ok {
 			allErrs = append(allErrs, errs.NewFieldInvalid("name", meta.Name, qualifier))
 		}
 	}
+
 	if requiresNamespace {
 		if len(meta.Namespace) == 0 {
 			allErrs = append(allErrs, errs.NewFieldRequired("namespace", meta.Namespace))
@@ -96,10 +122,6 @@ func ValidateObjectMeta(meta *api.ObjectMeta, requiresNamespace bool, nameFn Val
 	allErrs = append(allErrs, ValidateLabels(meta.Labels, "labels")...)
 	allErrs = append(allErrs, ValidateAnnotations(meta.Annotations, "annotations")...)
 
-	// Clear self link internally
-	// TODO: move to its own area
-	meta.SelfLink = ""
-
 	return allErrs
 }
 
@@ -131,10 +153,6 @@ func ValidateObjectMetaUpdate(old, meta *api.ObjectMeta) errs.ValidationErrorLis
 	allErrs = append(allErrs, ValidateLabels(meta.Labels, "labels")...)
 	allErrs = append(allErrs, ValidateAnnotations(meta.Annotations, "annotations")...)
 
-	// Clear self link internally
-	// TODO: move to its own area
-	meta.SelfLink = ""
-
 	return allErrs
 }
 
@@ -660,7 +678,7 @@ func ValidateBoundPod(pod *api.BoundPod) errs.ValidationErrorList {
 	if len(pod.Name) == 0 {
 		allErrs = append(allErrs, errs.NewFieldRequired("name", pod.Name))
 	} else {
-		if ok, qualifier := nameIsDNSSubdomain(pod.Name); !ok {
+		if ok, qualifier := nameIsDNSSubdomain(pod.Name, false); !ok {
 			allErrs = append(allErrs, errs.NewFieldInvalid("name", pod.Name, qualifier))
 		}
 	}