feat: support etag for declarative stores

go.work.sum

@@ -605,6 +605,7 @@ google.golang.org/genproto/googleapis/rpc v0.0.0-20240415180920-8c6c420018be/go.
 google.golang.org/genproto/googleapis/rpc v0.0.0-20240429193739-8cf5692501f6/go.mod h1:WtryC6hu0hhx87FDGxWCDptyssuo68sk10vYjF+T9fY=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20240528184218-531527333157/go.mod h1:EfXuqaE1J41VCDicxHzUDm+8rk+7ZdXzHV0IhO/I6s0=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20240610135401-a8a62080eff3/go.mod h1:EfXuqaE1J41VCDicxHzUDm+8rk+7ZdXzHV0IhO/I6s0=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20240624140628-dc46fd24d27d/go.mod h1:Ue6ibwXGpU+dqIcODieyLOcgj7z8+IcskoNIgZxtrFY=
 google.golang.org/grpc v1.37.0/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
 google.golang.org/grpc v1.62.1/go.mod h1:IWTG0VlJLCh1SkC58F7np9ka9mx/WNkjl4PGJaiq+QE=
 google.golang.org/grpc v1.63.2/go.mod h1:WAX/8DgncnokcFUldAxq7GeB5DXHDbMF+lLvDomNkRA=

internal/common/store_mock.go

@@ -19,7 +19,7 @@ func (m *StoreMock) String() string {
 }
 
 func (m *StoreMock) GetVersion(ctx context.Context, ns storage.NamespaceRequest) (string, error) {
-	args := m.Called(ctx)
+	args := m.Called(ctx, ns)
 	return args.String(0), args.Error(1)
 }
 

internal/ext/common.go

@@ -10,6 +10,7 @@ type Document struct {
 	Namespace string     `yaml:"namespace,omitempty" json:"namespace,omitempty"`
 	Flags     []*Flag    `yaml:"flags,omitempty" json:"flags,omitempty"`
 	Segments  []*Segment `yaml:"segments,omitempty" json:"segments,omitempty"`
+	Etag      string     `yaml:"-" json:"-"`
 }
 
 type Flag struct {

internal/storage/fs/object/store.go

@@ -161,8 +161,3 @@ func (s *SnapshotStore) getIndex(ctx context.Context) (*storagefs.FliptIndex, er
 	return idx, nil
 
 }
-
-func (s *SnapshotStore) GetVersion(ctx context.Context) (string, error) {
-	// TODO: implement
-	return "", nil
-}

internal/storage/fs/snapshot.go

@@ -46,6 +46,7 @@ type namespace struct {
 	rollouts     map[string]*flipt.Rollout
 	evalRules    map[string][]*storage.EvaluationRule
 	evalRollouts map[string][]*storage.EvaluationRollout
+	etag         string
 }
 
 func newNamespace(key, name string, created *timestamppb.Timestamp) *namespace {
@@ -226,6 +227,7 @@ func documentsFromFile(fi fs.File, opts SnapshotOption) ([]*ext.Document, error)
 		if doc.Namespace == "" {
 			doc.Namespace = "default"
 		}
+		doc.Etag = fmt.Sprintf("%x-%x", stat.ModTime().Unix(), stat.Size())
 		docs = append(docs, doc)
 	}
 
@@ -537,7 +539,7 @@ func (ss *Snapshot) addDoc(doc *ext.Document) error {
 
 		ns.evalRollouts[f.Key] = evalRollouts
 	}
-
+	ns.etag = doc.Etag
 	ss.ns[doc.Namespace] = ns
 
 	ss.evalDists = evalDists
@@ -860,7 +862,10 @@ func (ss *Snapshot) getNamespace(key string) (namespace, error) {
 	return *ns, nil
 }
 
-func (ss *Snapshot) GetVersion(context.Context, storage.NamespaceRequest) (string, error) {
-	// TODO: implement
-	return "", nil
+func (ss *Snapshot) GetVersion(ctx context.Context, req storage.NamespaceRequest) (string, error) {
+	ns, err := ss.getNamespace(req.Namespace())
+	if err != nil {
+		return "", err
+	}
+	return ns.etag, nil
 }

internal/storage/fs/snapshot_test.go

@@ -1740,6 +1740,16 @@ func (fis *FSWithoutIndexSuite) TestListAndGetRules() {
 	}
 }
 
+func (fis *FSWithoutIndexSuite) TestGetVersion() {
+	t := fis.T()
+	version, err := fis.store.GetVersion(context.Background(), storage.NewNamespace("production"))
+	require.NoError(t, err)
+	require.NotEmpty(t, version)
+	version, err = fis.store.GetVersion(context.Background(), storage.NewNamespace("unknown"))
+	require.Error(t, err)
+	require.Empty(t, version)
+}
+
 func TestFS_Empty_Features_File(t *testing.T) {
 	fs, _ := fs.Sub(testdata, "testdata/valid/empty_features")
 	ss, err := SnapshotFromFS(zaptest.NewLogger(t), fs)

internal/storage/fs/store.go

@@ -316,7 +316,9 @@ func (s *Store) OrderRollouts(ctx context.Context, r *flipt.OrderRolloutsRequest
 	return ErrNotImplemented
 }
 
-func (s *Store) GetVersion(context.Context, storage.NamespaceRequest) (string, error) {
-	// TODO: implement
-	return "", nil
+func (s *Store) GetVersion(ctx context.Context, ns storage.NamespaceRequest) (version string, err error) {
+	return version, s.viewer.View(ctx, ns.Reference, func(ss storage.ReadOnlyStore) error {
+		version, err = ss.GetVersion(ctx, ns)
+		return err
+	})
 }

internal/storage/fs/store_test.go

@@ -218,6 +218,18 @@ func TestGetEvaluationRollouts(t *testing.T) {
 	require.NoError(t, err)
 }
 
+func TestGetVersion(t *testing.T) {
+	storeMock := newSnapshotStoreMock()
+	ss := NewStore(storeMock)
+
+	ns := storage.NewNamespace("default")
+	storeMock.On("GetVersion", mock.Anything, ns).Return("x0-y1", nil)
+
+	version, err := ss.GetVersion(context.TODO(), ns)
+	require.NoError(t, err)
+	require.Equal(t, "x0-y1", version)
+}
+
 type snapshotStoreMock struct {
 	*common.StoreMock
 }