feat: postpone sandbox grpc connection time

internal/executors/sandbox/executor.go

@@ -10,11 +10,15 @@ import (
 )
 
 type Sandbox struct {
-	execClient pb.ExecutorClient
+	execServer, token string
 	cachedMap         map[string]string
+	execClient        pb.ExecutorClient
 }
 
 func (e *Sandbox) Run(cmds []stage.Cmd) ([]stage.ExecutorResult, error) {
+	if e.execClient == nil {
+		e.execClient = createExecClient(e.execServer, e.token)
+	}
 	// cannot use range loop since we need to change the value
 	for i := 0; i < len(cmds); i++ {
 		cmd := &cmds[i]

internal/executors/sandbox/meta.go

@@ -9,7 +9,8 @@ var name = "sandbox"
 func init() {
 	stage.RegisterExecutor(name, &Sandbox{
 		// TODO: read from conf
-		execClient: createExecClient("localhost:5051", ""),
+		execServer: "localhost:5051",
+		token:      "",
 		cachedMap:  make(map[string]string),
 	})
 }