karmada/pkg/registry/search/storage/cache.go

/*
Copyright 2022 The Karmada 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 storage

import (
	"encoding/json"
	"fmt"
	"net/http"

	metainternalversion "k8s.io/apimachinery/pkg/apis/meta/internalversion"
	metainternalversionvalidation "k8s.io/apimachinery/pkg/apis/meta/internalversion/validation"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	genericrequest "k8s.io/apiserver/pkg/endpoints/request"
	"k8s.io/apiserver/pkg/registry/rest"
	"k8s.io/klog/v2"

	clusterv1alpha1 "github.com/karmada-io/karmada/pkg/apis/cluster/v1alpha1"
	searchscheme "github.com/karmada-io/karmada/pkg/apis/search/scheme"
)

type errorResponse struct {
	Error string `json:"error"`
}

type reqResponse struct {
	metav1.TypeMeta `json:",inline"`
	metav1.ListMeta `json:"metadata,omitempty"`

	Items []runtime.Object `json:"items"`
}

func (r *SearchREST) newCacheHandler(info *genericrequest.RequestInfo, _ rest.Responder) (http.Handler, error) {
	resourceGVR := schema.GroupVersionResource{
		Group:    info.APIGroup,
		Version:  info.APIVersion,
		Resource: info.Resource,
	}

	return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
		enc := json.NewEncoder(rw)
		rw.Header().Set("Content-Type", "application/json")
		opts := metainternalversion.ListOptions{}
		if err := searchscheme.ParameterCodec.DecodeParameters(req.URL.Query(), metav1.SchemeGroupVersion, &opts); err != nil {
			rw.WriteHeader(http.StatusBadRequest)
			klog.Errorf("Failed to decode parameters from req.URL.Query(): %v", err)
			_ = enc.Encode(errorResponse{Error: err.Error()})
			return
		}

		if errs := metainternalversionvalidation.ValidateListOptions(&opts, false); len(errs) > 0 {
			rw.WriteHeader(http.StatusBadRequest)
			klog.Errorf("Invalid decoded ListOptions: %v.", errs)
			_ = enc.Encode(errorResponse{Error: errs.ToAggregate().Error()})
			return
		}

		label := labels.Everything()
		if opts.LabelSelector != nil {
			label = opts.LabelSelector
		}

		clusters, err := r.clusterLister.List(labels.Everything())
		if err != nil {
			rw.WriteHeader(http.StatusInternalServerError)
			_ = enc.Encode(errorResponse{Error: fmt.Sprintf("Failed to list clusters: %v", err)})
			return
		}

		// TODO: process opts.Limit to prevent the client from being unable to process the response
		// due to the large size of the response body.
		objItems := r.getObjectItemsFromClusters(clusters, resourceGVR, info.Namespace, info.Name, label)
		kind, err := r.restMapper.KindFor(resourceGVR)
		if err != nil {
			rw.WriteHeader(http.StatusInternalServerError)
			klog.Errorf("Failed to find kind, resource: %s, %v", resourceGVR.Resource, err)
			_ = enc.Encode(errorResponse{Error: err.Error()})
			return
		}
		rr := reqResponse{
			TypeMeta: metav1.TypeMeta{
				APIVersion: resourceGVR.GroupVersion().String(),
				Kind:       kind.Kind + "List",
			},
			Items: objItems,
		}
		rw.Header().Set("Content-Type", "application/json; charset=utf-8")
		_ = enc.Encode(rr)
	}), nil
}

func (r *SearchREST) getObjectItemsFromClusters(
	clusters []*clusterv1alpha1.Cluster,
	objGVR schema.GroupVersionResource,
	namespace, name string,
	label labels.Selector) []runtime.Object {
	items := make([]runtime.Object, 0)

	// TODO: encapsulating the Interface for Obtaining resource from the Multi-Cluster Cache.
	for _, cluster := range clusters {
		singleClusterManger := r.multiClusterInformerManager.GetSingleClusterManager(cluster.Name)
		if singleClusterManger == nil {
			klog.Warningf("SingleClusterInformerManager for cluster(%s) is nil.", cluster.Name)
			continue
		}

		var err error
		objLister := singleClusterManger.Lister(objGVR)
		if len(name) > 0 {
			var resourceObject runtime.Object
			if len(namespace) > 0 {
				resourceObject, err = objLister.ByNamespace(namespace).Get(name)
			} else {
				resourceObject, err = objLister.Get(name)
			}
			if err != nil {
				klog.Errorf("Failed to get %s resource(%s/%s) from cluster(%s)'s informer cache: %v",
					objGVR, namespace, name, cluster.Name, err)
				continue
			}
			items = append(items, addAnnotationWithClusterName([]runtime.Object{resourceObject.DeepCopyObject()}, cluster.Name)...)
		} else {
			var resourceObjects []runtime.Object
			if len(namespace) > 0 {
				resourceObjects, err = objLister.ByNamespace(namespace).List(label)
			} else {
				resourceObjects, err = objLister.List(label)
			}
			if err != nil {
				klog.Errorf("Failed to list %s resource from cluster(%s)'s informer cache: %v",
					objGVR, cluster.Name, err)
				continue
			}

			cloneObjects := make([]runtime.Object, len(resourceObjects))
			for i := range resourceObjects {
				cloneObjects[i] = resourceObjects[i].DeepCopyObject()
			}

			items = append(items, addAnnotationWithClusterName(cloneObjects, cluster.Name)...)
		}
	}

	return items
}

func addAnnotationWithClusterName(resourceObjects []runtime.Object, clusterName string) []runtime.Object {
	resources := make([]runtime.Object, 0)
	for index := range resourceObjects {
		resource := resourceObjects[index].(*unstructured.Unstructured)

		annotations := resource.GetAnnotations()
		if annotations == nil {
			annotations = make(map[string]string)
		}

		annotations[clusterv1alpha1.CacheSourceAnnotationKey] = clusterName

		resource.SetAnnotations(annotations)
		resources = append(resources, resource)
	}

	return resources
}