(feat) Add auto-discovery in k8s | Adarsh

vendor/k8s.io/apimachinery/pkg/api/meta/firsthit_restmapper.go

@@ -0,0 +1,97 @@
+/*
+Copyright 2014 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package meta
+
+import (
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	utilerrors "k8s.io/apimachinery/pkg/util/errors"
+)
+
+// FirstHitRESTMapper is a wrapper for multiple RESTMappers which returns the
+// first successful result for the singular requests
+type FirstHitRESTMapper struct {
+	MultiRESTMapper
+}
+
+func (m FirstHitRESTMapper) String() string {
+	return fmt.Sprintf("FirstHitRESTMapper{\n\t%v\n}", m.MultiRESTMapper)
+}
+
+func (m FirstHitRESTMapper) ResourceFor(resource schema.GroupVersionResource) (schema.GroupVersionResource, error) {
+	errors := []error{}
+	for _, t := range m.MultiRESTMapper {
+		ret, err := t.ResourceFor(resource)
+		if err == nil {
+			return ret, nil
+		}
+		errors = append(errors, err)
+	}
+
+	return schema.GroupVersionResource{}, collapseAggregateErrors(errors)
+}
+
+func (m FirstHitRESTMapper) KindFor(resource schema.GroupVersionResource) (schema.GroupVersionKind, error) {
+	errors := []error{}
+	for _, t := range m.MultiRESTMapper {
+		ret, err := t.KindFor(resource)
+		if err == nil {
+			return ret, nil
+		}
+		errors = append(errors, err)
+	}
+
+	return schema.GroupVersionKind{}, collapseAggregateErrors(errors)
+}
+
+// RESTMapping provides the REST mapping for the resource based on the
+// kind and version. This implementation supports multiple REST schemas and
+// return the first match.
+func (m FirstHitRESTMapper) RESTMapping(gk schema.GroupKind, versions ...string) (*RESTMapping, error) {
+	errors := []error{}
+	for _, t := range m.MultiRESTMapper {
+		ret, err := t.RESTMapping(gk, versions...)
+		if err == nil {
+			return ret, nil
+		}
+		errors = append(errors, err)
+	}
+
+	return nil, collapseAggregateErrors(errors)
+}
+
+// collapseAggregateErrors returns the minimal errors.  it handles empty as nil, handles one item in a list
+// by returning the item, and collapses all NoMatchErrors to a single one (since they should all be the same)
+func collapseAggregateErrors(errors []error) error {
+	if len(errors) == 0 {
+		return nil
+	}
+	if len(errors) == 1 {
+		return errors[0]
+	}
+
+	allNoMatchErrors := true
+	for _, err := range errors {
+		allNoMatchErrors = allNoMatchErrors && IsNoMatchError(err)
+	}
+	if allNoMatchErrors {
+		return errors[0]
+	}
+
+	return utilerrors.NewAggregate(errors)
+}