Add DaemonSet templateGeneration validation and tests, and fix a bunch of validation test errors

pkg/apis/extensions/validation/validation.go

@@ -98,10 +98,30 @@ func ValidateDaemonSet(ds *extensions.DaemonSet) field.ErrorList {
 // ValidateDaemonSetUpdate tests if required fields in the DaemonSet are set.
 func ValidateDaemonSetUpdate(ds, oldDS *extensions.DaemonSet) field.ErrorList {
 	allErrs := apivalidation.ValidateObjectMetaUpdate(&ds.ObjectMeta, &oldDS.ObjectMeta, field.NewPath("metadata"))
+	allErrs = append(allErrs, ValidateDaemonSetSpecUpdate(&ds.Spec, &oldDS.Spec, field.NewPath("spec"))...)
 	allErrs = append(allErrs, ValidateDaemonSetSpec(&ds.Spec, field.NewPath("spec"))...)
 	return allErrs
 }
 
+func ValidateDaemonSetSpecUpdate(newSpec, oldSpec *extensions.DaemonSetSpec, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+
+	// TemplateGeneration shouldn't be decremented
+	if newSpec.TemplateGeneration < oldSpec.TemplateGeneration {
+		allErrs = append(allErrs, field.Invalid(fldPath.Child("templateGeneration"), newSpec.TemplateGeneration, "must not be decremented"))
+	}
+
+	// TemplateGeneration should be increased when and only when template is changed
+	templateUpdated := !reflect.DeepEqual(newSpec.Template, oldSpec.Template)
+	if newSpec.TemplateGeneration == oldSpec.TemplateGeneration && templateUpdated {
+		allErrs = append(allErrs, field.Invalid(fldPath.Child("templateGeneration"), newSpec.TemplateGeneration, "must be incremented upon template update"))
+	} else if newSpec.TemplateGeneration > oldSpec.TemplateGeneration && !templateUpdated {
+		allErrs = append(allErrs, field.Invalid(fldPath.Child("templateGeneration"), newSpec.TemplateGeneration, "must not be incremented without template update"))
+	}
+
+	return allErrs
+}
+
 // validateDaemonSetStatus validates a DaemonSetStatus
 func validateDaemonSetStatus(status *extensions.DaemonSetStatus, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}