Allow v2deprecation mode of write-only

Signed-off-by: Geeta Gharpure <geetagh@amazon.com>

server/config/v2_deprecation.go

@@ -27,7 +27,8 @@ const (
 	// V2store is neither written nor read for 3.6. v2snapshot is published only for backward compatibility
 	V2_DEPR_2_GONE = V2DeprecationEnum("gone")
 
-	V2_DEPR_DEFAULT = V2_DEPR_2_GONE
+	//TODO geetasg does thie default need to change
+	V2_DEPR_DEFAULT = V2_DEPR_1_WRITE_ONLY
 )
 
 func (e V2DeprecationEnum) IsAtLeast(v2d V2DeprecationEnum) bool {

server/etcdserver/bootstrap.go

@@ -394,6 +394,10 @@ func recoverSnapshot(cfg config.ServerConfig, st v2store.Store, be backend.Backe
 	}
 
 	if snapshot != nil {
+		if err := serverstorage.AssertV2DeprecationStage(cfg.Logger, cfg.V2Deprecation); err != nil {
+			cfg.Logger.Panic("illegal v2store content", zap.Error(err))
+		}
+
 		if be, err = serverstorage.RecoverSnapshotBackend(cfg, be, *snapshot, beExist, beHooks); err != nil {
 			cfg.Logger.Panic("failed to recover v3 backend from snapshot", zap.Error(err))
 		}

server/etcdserver/bootstrap_test.go

@@ -187,6 +187,7 @@ func TestBootstrapBackend(t *testing.T) {
 				DataDir:             dataDir,
 				BackendFreelistType: bolt.FreelistArrayType,
 				Logger:              zaptest.NewLogger(t),
+				V2Deprecation:       config.V2_DEPR_DEFAULT,
 			}
 
 			if tt.prepareData != nil {

server/etcdserver/server.go

@@ -1046,6 +1046,10 @@ func (s *EtcdServer) applySnapshot(ep *etcdProgress, toApply *toApply) {
 		lg.Info("restored auth store")
 	}
 
+	if err := serverstorage.AssertV2DeprecationStage(lg, s.Cfg.V2Deprecation); err != nil {
+		lg.Panic("illegal v2store content", zap.Error(err))
+	}
+
 	s.cluster.SetBackend(schema.NewMembershipBackend(lg, newbe))
 
 	lg.Info("restoring cluster configuration")

server/etcdserver/server_test.go

@@ -1195,7 +1195,7 @@ func TestSnapshotOrdering(t *testing.T) {
 	s := &EtcdServer{
 		lgMu:         new(sync.RWMutex),
 		lg:           lg,
-		Cfg:          config.ServerConfig{Logger: lg, DataDir: testdir, SnapshotCatchUpEntries: DefaultSnapshotCatchUpEntries, V2Deprecation: config.V2_DEPR_2_GONE},
+		Cfg:          config.ServerConfig{Logger: lg, DataDir: testdir, SnapshotCatchUpEntries: DefaultSnapshotCatchUpEntries, V2Deprecation: config.V2_DEPR_DEFAULT},
 		r:            *r,
 		snapshotter:  snap.New(lg, snapdir),
 		cluster:      cl,

server/storage/util.go

@@ -32,17 +32,23 @@ import (
 // AssertNoV2StoreContent -> depending on the deprecation stage, warns or report an error
 // if the v2store contains custom content.
 func AssertNoV2StoreContent(lg *zap.Logger, st v2store.Store, deprecationStage config.V2DeprecationEnum) error {
+	//TODO remove this method.
 	metaOnly, err := membership.IsMetaStoreOnly(st)
 	if err != nil {
 		return err
 	}
 	if metaOnly {
 		return nil
 	}
-	if deprecationStage.IsAtLeast(config.V2_DEPR_1_WRITE_ONLY) {
-		return fmt.Errorf("detected disallowed custom content in v2store for stage --v2-deprecation=%s", deprecationStage)
+	return AssertV2DeprecationStage(lg, deprecationStage)
+}
+
+func AssertV2DeprecationStage(lg *zap.Logger, deprecationStage config.V2DeprecationEnum) error {
+	//TODO geetasg should the write-only be supported? Update TestV2DeprecationFlags accordingly
+	//supported stages are "write-only", "write-only-drop-data" and "gone"
+	if !deprecationStage.IsAtLeast(config.V2_DEPR_1_WRITE_ONLY) {
+		return fmt.Errorf("Unsupported stage --v2-deprecation=%s", deprecationStage)
 	}
-	lg.Warn("detected custom v2store content. Etcd v3.5 is the last version allowing to access it using API v2. Please remove the content.")
 	return nil
 }
 

tests/e2e/v2store_deprecation_test.go

@@ -101,9 +101,12 @@ func TestV2DeprecationFlags(t *testing.T) {
 		assertVerifyCannotStartV2deprecationNotYet(t, memberDataDir)
 	})
 
-	t.Run("--v2-deprecation=write-only fails", func(t *testing.T) {
-		assertVerifyCannotStartV2deprecationWriteOnly(t, memberDataDir)
-	})
+	//It is ok to start with write-only in 3.6
+	/*
+		t.Run("--v2-deprecation=write-only fails", func(t *testing.T) {
+			assertVerifyCannotStartV2deprecationWriteOnly(t, memberDataDir)
+		})
+	*/
 
 }