Filter out primary tablet type in switch reads from the tablet types …

…passed in the request

Signed-off-by: Rohit Nayak <[email protected]>

go/vt/vtctl/workflow/server.go

@@ -3017,10 +3017,16 @@ func (s *Server) switchReads(ctx context.Context, req *vtctldatapb.WorkflowSwitc
 	}
 	defer unlock(&err)
 
+	var tabletTypes []topodatapb.TabletType
+	for _, tabletType := range req.TabletTypes {
+		if tabletType != topodatapb.TabletType_PRIMARY {
+			tabletTypes = append(tabletTypes, tabletType)
+		}
+	}
 	if ts.MigrationType() == binlogdatapb.MigrationType_TABLES {
 		if ts.isPartialMigration {
 			ts.Logger().Infof("Partial migration, skipping switchTableReads as traffic is all or nothing per shard and overridden for reads AND writes in the ShardRoutingRule created when switching writes.")
-		} else if err := sw.switchTableReads(ctx, cells, req.TabletTypes, direction); err != nil {
+		} else if err := sw.switchTableReads(ctx, cells, tabletTypes, direction); err != nil {
 			return handleError("failed to switch read traffic for the tables", err)
 		}
 		return sw.logs(), nil

go/vt/vtctl/workflow/traffic_switcher.go

@@ -587,6 +587,10 @@ func (ts *trafficSwitcher) switchTableReads(ctx context.Context, cells []string,
 	// For forward migration, we add tablet type specific rules to redirect traffic to the target.
 	// For backward, we redirect to source.
 	for _, servedType := range servedTypes {
+		if servedType != topodatapb.TabletType_REPLICA && servedType != topodatapb.TabletType_RDONLY {
+			return fmt.Errorf("invalid tablet type specified for switchTableReads: %v", servedType)
+		}
+
 		tt := strings.ToLower(servedType.String())
 		for _, table := range ts.Tables() {
 			if direction == DirectionForward {