Add CacheControl headers to GCP (#400)

storage/gcp/gcp.go

@@ -59,15 +59,17 @@ import (
 )
 
 const (
-	entryBundleSize = 256
-	logContType     = "application/octet-stream"
-	ckptContType    = "text/plain; charset=utf-8"
 	// minCheckpointInterval is the shortest permitted interval between updating published checkpoints.
 	// GCS has a rate limit 1 update per second for individual objects, but we've observed that attempting
 	// to update at exactly that rate still results in the occasional refusal, so bake in a little wiggle
 	// room.
 	minCheckpointInterval = 1200 * time.Millisecond
 
+	logContType      = "application/octet-stream"
+	ckptContType     = "text/plain; charset=utf-8"
+	logCacheControl  = "max-age=604800,immutable"
+	ckptCacheControl = "no-cache"
+
 	DefaultPushbackMaxOutstanding = 4096
 	DefaultIntegrationSizeLimit   = 5 * 4096
 )
@@ -88,7 +90,7 @@ type Storage struct {
 // objStore describes a type which can store and retrieve objects.
 type objStore interface {
 	getObject(ctx context.Context, obj string) ([]byte, int64, error)
-	setObject(ctx context.Context, obj string, data []byte, cond *gcs.Conditions, contType string) error
+	setObject(ctx context.Context, obj string, data []byte, cond *gcs.Conditions, contType string, cacheCtl string) error
 	lastModified(ctx context.Context, obj string) (time.Time, error)
 }
 
@@ -270,7 +272,7 @@ func (s *Storage) publishCheckpoint(ctx context.Context, minStaleness time.Durat
 		return fmt.Errorf("newCP: %v", err)
 	}
 
-	if err := s.objStore.setObject(ctx, layout.CheckpointPath, cpRaw, nil, ckptContType); err != nil {
+	if err := s.objStore.setObject(ctx, layout.CheckpointPath, cpRaw, nil, ckptContType, ckptCacheControl); err != nil {
 		return fmt.Errorf("writeCheckpoint: %v", err)
 	}
 	return nil
@@ -288,7 +290,7 @@ func (s *Storage) setTile(ctx context.Context, level, index, logSize uint64, til
 	tPath := layout.TilePath(level, index, layout.PartialTileSize(level, index, logSize))
 	klog.V(2).Infof("StoreTile: %s (%d entries)", tPath, len(tile.Nodes))
 
-	return s.objStore.setObject(ctx, tPath, data, &gcs.Conditions{DoesNotExist: true}, logContType)
+	return s.objStore.setObject(ctx, tPath, data, &gcs.Conditions{DoesNotExist: true}, logContType, logCacheControl)
 }
 
 // getTiles returns the tiles with the given tile-coords for the specified log size.
@@ -351,7 +353,7 @@ func (s *Storage) setEntryBundle(ctx context.Context, bundleIndex uint64, p uint
 	// Note that setObject does an idempotent interpretation of DoesNotExist - it only
 	// returns an error if the named object exists _and_ contains different data to what's
 	// passed in here.
-	if err := s.objStore.setObject(ctx, objName, bundleRaw, &gcs.Conditions{DoesNotExist: true}, logContType); err != nil {
+	if err := s.objStore.setObject(ctx, objName, bundleRaw, &gcs.Conditions{DoesNotExist: true}, logContType, logCacheControl); err != nil {
 		return fmt.Errorf("setObject(%q): %v", objName, err)
 
 	}
@@ -748,7 +750,7 @@ func (s *gcsStorage) getObject(ctx context.Context, obj string) ([]byte, int64,
 // Note that when preconditions are specified and are not met, an error will be returned *unless*
 // the currently stored data is bit-for-bit identical to the data to-be-written.
 // This is intended to provide idempotentency for writes.
-func (s *gcsStorage) setObject(ctx context.Context, objName string, data []byte, cond *gcs.Conditions, contType string) error {
+func (s *gcsStorage) setObject(ctx context.Context, objName string, data []byte, cond *gcs.Conditions, contType string, cacheCtl string) error {
 	bkt := s.gcsClient.Bucket(s.bucket)
 	obj := bkt.Object(objName)
 
@@ -760,6 +762,7 @@ func (s *gcsStorage) setObject(ctx context.Context, objName string, data []byte,
 		w = obj.If(*cond).NewWriter(ctx)
 	}
 	w.ObjectAttrs.ContentType = contType
+	w.ObjectAttrs.CacheControl = cacheCtl
 	if _, err := w.Write(data); err != nil {
 		return fmt.Errorf("failed to write object %q to bucket %q: %w", objName, s.bucket, err)
 	}

storage/gcp/gcp_test.go

@@ -347,7 +347,7 @@ func TestPublishCheckpoint(t *testing.T) {
 				t.Fatalf("storage.init: %v", err)
 			}
 			cpOld := []byte("bananas")
-			if err := m.setObject(ctx, layout.CheckpointPath, cpOld, nil, ""); err != nil {
+			if err := m.setObject(ctx, layout.CheckpointPath, cpOld, nil, "", ""); err != nil {
 				t.Fatalf("setObject(bananas): %v", err)
 			}
 			m.lMod = test.cpModifiedAt
@@ -394,7 +394,7 @@ func (m *memObjStore) getObject(_ context.Context, obj string) ([]byte, int64, e
 }
 
 // TODO(phboneff): add content type tests
-func (m *memObjStore) setObject(_ context.Context, obj string, data []byte, cond *gcs.Conditions, _ string) error {
+func (m *memObjStore) setObject(_ context.Context, obj string, data []byte, cond *gcs.Conditions, _, _ string) error {
 	m.Lock()
 	defer m.Unlock()