controllerrestmapper: implement RESTMappings

This function is needed for mapping from a group kind
to a group version kind, which will be needed for pruning.

pkg/restmapper/caching.go

@@ -8,6 +8,7 @@ import (
 
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/client-go/discovery"
 	"k8s.io/klog/v2"
@@ -17,6 +18,7 @@ import (
 // cache is our cache of schema information.
 type cache struct {
 	mutex         sync.Mutex
+	groups        map[string]metav1.APIGroup
 	groupVersions map[schema.GroupVersion]*cachedGroupVersion
 }
 
@@ -27,6 +29,34 @@ func newCache() *cache {
 	}
 }
 
+// findGroupInfo returns the APIGroup for the specified group, querying discovery if not cached.
+// If not found, returns APIGroup{}, false, nil
+func (c *cache) findGroupInfo(ctx context.Context, discovery discovery.DiscoveryInterface, groupName string) (metav1.APIGroup, bool, error) {
+	log := log.FromContext(ctx)
+
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+
+	if c.groups == nil {
+		log.Info("discovering server groups")
+		serverGroups, err := discovery.ServerGroups()
+		if err != nil {
+			klog.Infof("unexpected error from ServerGroups: %w", err)
+			return metav1.APIGroup{}, false, fmt.Errorf("error from ServerGroups: %w", err)
+		}
+
+		groups := make(map[string]metav1.APIGroup)
+		for i := range serverGroups.Groups {
+			group := &serverGroups.Groups[i]
+			groups[group.Name] = *group
+		}
+		c.groups = groups
+	}
+
+	group, found := c.groups[groupName]
+	return group, found, nil
+}
+
 // cachedGroupVersion caches (all) the resource information for a particular groupversion.
 type cachedGroupVersion struct {
 	gv    schema.GroupVersion

pkg/restmapper/controllerrestmapper.go

@@ -35,22 +35,22 @@ var _ meta.RESTMapper = &ControllerRESTMapper{}
 
 // KindFor takes a partial resource and returns the single match.  Returns an error if there are multiple matches
 func (m *ControllerRESTMapper) KindFor(resource schema.GroupVersionResource) (schema.GroupVersionKind, error) {
-	return schema.GroupVersionKind{}, fmt.Errorf("ControllerRESTMaper does not support KindFor operation")
+	return schema.GroupVersionKind{}, fmt.Errorf("ControllerRESTMapper does not support KindFor operation")
 }
 
 // KindsFor takes a partial resource and returns the list of potential kinds in priority order
 func (m *ControllerRESTMapper) KindsFor(resource schema.GroupVersionResource) ([]schema.GroupVersionKind, error) {
-	return nil, fmt.Errorf("ControllerRESTMaper does not support KindsFor operation")
+	return nil, fmt.Errorf("ControllerRESTMapper does not support KindsFor operation")
 }
 
 // ResourceFor takes a partial resource and returns the single match.  Returns an error if there are multiple matches
 func (m *ControllerRESTMapper) ResourceFor(input schema.GroupVersionResource) (schema.GroupVersionResource, error) {
-	return schema.GroupVersionResource{}, fmt.Errorf("ControllerRESTMaper does not support ResourceFor operation")
+	return schema.GroupVersionResource{}, fmt.Errorf("ControllerRESTMapper does not support ResourceFor operation")
 }
 
 // ResourcesFor takes a partial resource and returns the list of potential resource in priority order
 func (m *ControllerRESTMapper) ResourcesFor(input schema.GroupVersionResource) ([]schema.GroupVersionResource, error) {
-	return nil, fmt.Errorf("ControllerRESTMaper does not support ResourcesFor operation")
+	return nil, fmt.Errorf("ControllerRESTMapper does not support ResourcesFor operation")
 }
 
 // RESTMapping identifies a preferred resource mapping for the provided group kind.
@@ -75,9 +75,53 @@ func (m *ControllerRESTMapper) RESTMapping(gk schema.GroupKind, versions ...stri
 // version search is provided. Otherwise identifies a preferred resource mapping for
 // the provided version(s).
 func (m *ControllerRESTMapper) RESTMappings(gk schema.GroupKind, versions ...string) ([]*meta.RESTMapping, error) {
-	return nil, fmt.Errorf("ControllerRESTMaper does not support RESTMappings operation")
+	ctx := context.TODO()
+
+	if len(versions) != 0 {
+		return nil, fmt.Errorf("ControllerRESTMapper does not support RESTMappings operation with specified versions")
+	}
+
+	group, found, err := m.cache.findGroupInfo(ctx, m.uncached, gk.Group)
+	if err != nil {
+		return nil, err
+	}
+	if !found {
+		return nil, &meta.NoResourceMatchError{PartialResource: schema.GroupVersionResource{Group: gk.Group, Resource: gk.Kind}}
+	}
+
+	var mappings []*meta.RESTMapping
+
+	if group.PreferredVersion.Version != "" {
+		gv := schema.GroupVersion{Group: gk.Group, Version: group.PreferredVersion.Version}
+		mapping, err := m.cache.findRESTMapping(ctx, m.uncached, gv, gk.Kind)
+		if err != nil {
+			return nil, err
+		}
+		if mapping != nil {
+			mappings = append(mappings, mapping)
+		}
+	}
+
+	for i := range group.Versions {
+		gv := schema.GroupVersion{Group: gk.Group, Version: group.Versions[i].Version}
+		if gv.Version == group.PreferredVersion.Version {
+			continue
+		}
+		mapping, err := m.cache.findRESTMapping(ctx, m.uncached, gv, gk.Kind)
+		if err != nil {
+			return nil, err
+		}
+		if mapping != nil {
+			mappings = append(mappings, mapping)
+		}
+	}
+
+	if len(mappings) == 0 {
+		return nil, &meta.NoResourceMatchError{PartialResource: schema.GroupVersionResource{Group: gk.Group, Resource: gk.Kind}}
+	}
+	return mappings, nil
 }
 
 func (m *ControllerRESTMapper) ResourceSingularizer(resource string) (singular string, err error) {
-	return "", fmt.Errorf("ControllerRESTMaper does not support ResourceSingularizer operation")
+	return "", fmt.Errorf("ControllerRESTMapper does not support ResourceSingularizer operation")
 }