discovery.go

/*
Copyright 2016 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.
*/

// This code is lifted from the Kubernetes codebase in order to avoid relying on the k8s.io/kubernetes package.
// For reference:
// https://github.com/kubernetes/kubernetes/blob/release-1.23/pkg/controller/garbagecollector/garbagecollector.go#L696-L732

package lifted

import (
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/client-go/discovery"
	"k8s.io/klog/v2"
)

// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.23/pkg/controller/garbagecollector/garbagecollector.go#L696-L732

// GetDeletableResources returns all resources from discoveryClient that the
// garbage collector should recognize and work with. More specifically, all
// preferred resources which support the 'delete', 'list', and 'watch' verbs.
//
// All discovery errors are considered temporary. Upon encountering any error,
// GetDeletableResources will log and return any discovered resources it was
// able to process (which may be none).
func GetDeletableResources(discoveryClient discovery.ServerResourcesInterface) map[schema.GroupVersionResource]struct{} {
	preferredResources, err := discoveryClient.ServerPreferredResources()
	if err != nil {
		if discovery.IsGroupDiscoveryFailedError(err) {
			klog.Warningf("failed to discover some groups: %v", err.(*discovery.ErrGroupDiscoveryFailed).Groups)
		} else {
			klog.Warningf("failed to discover preferred resources: %v", err)
		}
	}
	if preferredResources == nil {
		return map[schema.GroupVersionResource]struct{}{}
	}

	// This is extracted from discovery.GroupVersionResources to allow tolerating
	// failures on a per-resource basis.
	deletableResources := discovery.FilteredBy(discovery.SupportsAllVerbs{Verbs: []string{"delete", "list", "watch"}}, preferredResources)
	deletableGroupVersionResources := map[schema.GroupVersionResource]struct{}{}
	for _, rl := range deletableResources {
		gv, err := schema.ParseGroupVersion(rl.GroupVersion)
		if err != nil {
			klog.Warningf("ignoring invalid discovered resource %q: %v", rl.GroupVersion, err)
			continue
		}
		for i := range rl.APIResources {
			deletableGroupVersionResources[schema.GroupVersionResource{Group: gv.Group, Version: gv.Version, Resource: rl.APIResources[i].Name}] = struct{}{}
		}
	}

	return deletableGroupVersionResources
}