Add GroupLister interface to discovery GroupManager

Signed-off-by: Mangirdas Judeikis <[email protected]>

Author: mjudeikis

staging/src/k8s.io/apiserver/pkg/endpoints/discovery/root.go

@@ -17,6 +17,7 @@ limitations under the License.
 package discovery
 
 import (
+	"context"
 	"net/http"
 	"sync"
 
@@ -33,12 +34,21 @@ import (
 // GroupManager is an interface that allows dynamic mutation of the existing webservice to handle
 // API groups being added or removed.
 type GroupManager interface {
+	GroupLister
+
 	AddGroup(apiGroup metav1.APIGroup)
 	RemoveGroup(groupName string)
 	ServeHTTP(resp http.ResponseWriter, req *http.Request)
 	WebService() *restful.WebService
 }
 
+// GroupLister knows how to list APIGroups for discovery.
+type GroupLister interface {
+	// Groups returns APIGroups for discovery, filling in ServerAddressByClientCIDRs
+	// based on data in req.
+	Groups(ctx context.Context, req *http.Request) ([]metav1.APIGroup, error)
+}
+
 // rootAPIsHandler creates a webservice serving api group discovery.
 // The list of APIGroups may change while the server is running because additional resources
 // are registered or removed.  It is not safe to cache the values.
@@ -94,24 +104,40 @@ func (s *rootAPIsHandler) RemoveGroup(groupName string) {
 	}
 }
 
-func (s *rootAPIsHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
+func (s *rootAPIsHandler) Groups(ctx context.Context, req *http.Request) ([]metav1.APIGroup, error) {
 	s.lock.RLock()
 	defer s.lock.RUnlock()
 
+	return s.groupsLocked(ctx, req), nil
+}
+
+// groupsLocked returns the APIGroupList discovery information for this handler.
+// The caller must hold the lock before invoking this method to avoid data races.
+func (s *rootAPIsHandler) groupsLocked(ctx context.Context, req *http.Request) []metav1.APIGroup {
+	clientIP := utilnet.GetClientIP(req)
+	serverCIDR := s.addresses.ServerAddressByClientCIDRs(clientIP)
+
 	orderedGroups := []metav1.APIGroup{}
 	for _, groupName := range s.apiGroupNames {
 		orderedGroups = append(orderedGroups, s.apiGroups[groupName])
 	}
 
-	clientIP := utilnet.GetClientIP(req)
-	serverCIDR := s.addresses.ServerAddressByClientCIDRs(clientIP)
 	groups := make([]metav1.APIGroup, len(orderedGroups))
 	for i := range orderedGroups {
 		groups[i] = orderedGroups[i]
 		groups[i].ServerAddressByClientCIDRs = serverCIDR
 	}
 
-	responsewriters.WriteObjectNegotiated(s.serializer, negotiation.DefaultEndpointRestrictions, schema.GroupVersion{}, resp, req, http.StatusOK, &metav1.APIGroupList{Groups: groups}, false)
+	return groups
+}
+
+func (s *rootAPIsHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+
+	groupList := metav1.APIGroupList{Groups: s.groupsLocked(req.Context(), req)}
+
+	responsewriters.WriteObjectNegotiated(s.serializer, negotiation.DefaultEndpointRestrictions, schema.GroupVersion{}, resp, req, http.StatusOK, &groupList, false)
 }
 
 func (s *rootAPIsHandler) restfulHandle(req *restful.Request, resp *restful.Response) {

staging/src/k8s.io/apiserver/pkg/endpoints/discovery/root_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package discovery
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -173,6 +174,13 @@ func TestDiscoveryOrdering(t *testing.T) {
 		t.Fatalf("unexpected error: %v", err)
 	}
 
+	// Check if internal groups listers returns the same group.
+	groups, err := handler.Groups(context.TODO(), &http.Request{})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	assert.Len(t, groups, 6)
+
 	assert.Len(t, groupList.Groups, 6)
 	assert.Equal(t, "x", groupList.Groups[0].Name)
 	assert.Equal(t, "y", groupList.Groups[1].Name)