Update Google Cloud DNS List implementation to perform a paged walk of lists to aggregate all the DNS records.

The current `List()` implementation just lists the DNS resorce records in
a given managed zone once and retruns the list. It neither performs a paged
walk nor does it consider the `page_token` in the returned response.

This change walks all the pages and aggregates the records in the pages
and returns the aggregated list. This is potentially dangerous as it can
blow up memory if there are a huge number of records in the given
managed zone. But this is the best we can do without changing the
provider interface too much. Next step is to define a new paged list
interface and implement it.

federation/pkg/dnsprovider/providers/google/clouddns/internal/interfaces/interfaces.go

@@ -17,6 +17,8 @@ limitations under the License.
 package interfaces
 
 import (
+	"context"
+
 	"google.golang.org/api/googleapi"
 	"k8s.io/kubernetes/federation/pkg/dnsprovider/rrstype"
 )
@@ -172,8 +174,8 @@ type (
 
 	ResourceRecordSetsListCall interface {
 		// Context(ctx context.Context) *ResourceRecordSetsListCall  // TODO: Add as needed
-		// Do(opts ...googleapi.CallOption) (*ResourceRecordSetsListResponse, error)  // TODO: Add as needed
 		Do(opts ...googleapi.CallOption) (ResourceRecordSetsListResponse, error)
+		Pages(ctx context.Context, f func(ResourceRecordSetsListResponse) error) error
 		// Fields(s ...googleapi.Field) *ResourceRecordSetsListCall  // TODO: Add as needed
 		// IfNoneMatch(entityTag string) *ResourceRecordSetsListCall  // TODO: Add as needed
 		// MaxResults(maxResults int64) *ResourceRecordSetsListCall  // TODO: Add as needed

federation/pkg/dnsprovider/providers/google/clouddns/internal/rrsets_list_call.go

@@ -17,6 +17,8 @@ limitations under the License.
 package internal
 
 import (
+	"context"
+
 	dns "google.golang.org/api/dns/v1"
 	"google.golang.org/api/googleapi"
 	"k8s.io/kubernetes/federation/pkg/dnsprovider/providers/google/clouddns/internal/interfaces"
@@ -34,6 +36,12 @@ func (call *ResourceRecordSetsListCall) Do(opts ...googleapi.CallOption) (interf
 	return &ResourceRecordSetsListResponse{response}, err
 }
 
+func (call *ResourceRecordSetsListCall) Pages(ctx context.Context, f func(interfaces.ResourceRecordSetsListResponse) error) error {
+	return call.impl.Pages(ctx, func(page *dns.ResourceRecordSetsListResponse) error {
+		return f(&ResourceRecordSetsListResponse{page})
+	})
+}
+
 func (call *ResourceRecordSetsListCall) Name(name string) interfaces.ResourceRecordSetsListCall {
 	call.impl.Name(name)
 	return call

federation/pkg/dnsprovider/providers/google/clouddns/internal/stubs/rrsets_list_call.go

@@ -17,6 +17,8 @@ limitations under the License.
 package stubs
 
 import (
+	"context"
+
 	"google.golang.org/api/googleapi"
 	"k8s.io/kubernetes/federation/pkg/dnsprovider/providers/google/clouddns/internal/interfaces"
 )
@@ -35,6 +37,10 @@ func (call *ResourceRecordSetsListCall) Do(opts ...googleapi.CallOption) (interf
 	return call.Response_, call.Err_
 }
 
+func (call *ResourceRecordSetsListCall) Pages(ctx context.Context, f func(interfaces.ResourceRecordSetsListResponse) error) error {
+	return f(call.Response_)
+}
+
 func (call *ResourceRecordSetsListCall) Name(name string) interfaces.ResourceRecordSetsListCall {
 	call.Name_ = name
 	return call

federation/pkg/dnsprovider/providers/google/clouddns/rrsets.go

@@ -17,6 +17,8 @@ limitations under the License.
 package clouddns
 
 import (
+	"context"
+
 	"k8s.io/kubernetes/federation/pkg/dnsprovider"
 	"k8s.io/kubernetes/federation/pkg/dnsprovider/providers/google/clouddns/internal/interfaces"
 	"k8s.io/kubernetes/federation/pkg/dnsprovider/rrstype"
@@ -30,15 +32,26 @@ type ResourceRecordSets struct {
 	impl interfaces.ResourceRecordSetsService
 }
 
+// List returns a list of resource records in the given project and
+// managed zone.
+// !!CAUTION!! Your memory might explode if you have a huge number of
+// records in your managed zone.
 func (rrsets ResourceRecordSets) List() ([]dnsprovider.ResourceRecordSet, error) {
-	response, err := rrsets.impl.List(rrsets.project(), rrsets.zone.impl.Name()).Do()
+	var list []dnsprovider.ResourceRecordSet
+
+	ctx := context.Background()
+
+	call := rrsets.impl.List(rrsets.project(), rrsets.zone.impl.Name())
+	err := call.Pages(ctx, func(page interfaces.ResourceRecordSetsListResponse) error {
+		for _, rrset := range page.Rrsets() {
+			list = append(list, ResourceRecordSet{rrset, &rrsets})
+		}
+		return nil
+	})
 	if err != nil {
 		return nil, err
 	}
-	list := make([]dnsprovider.ResourceRecordSet, len(response.Rrsets()))
-	for i, rrset := range response.Rrsets() {
-		list[i] = ResourceRecordSet{rrset, &rrsets}
-	}
+
 	return list, nil
 }