nodejs 쿠키세션 질문입니다.

--dbconfig.js
 const dbConfig = { 
    user : "java", 
    password : "1234",
    connectString : "localhost:1521/xe"
}
module.exports = dbConfig;

--cookie_session.js

const sessionConfig = {
    secret : "암호화 키",
    resave : false,
    saveUninitialized : true
    //cookie : { maxAge : 500000}

}
module.exports = {sessionConfig};

-- app.js

const express = require("express");

const app = express();

const bodyParser = require("body-parser");
app.use( bodyParser.urlencoded({ extended : true }) );

const session = require("express-session");
const sessionConfig =  require("./config/cookie_session/cookie_session_config");
app.use( session(sessionConfig.sessionConfig) );
const cookieParser = require("cookie-parser");
app.use( cookieParser() );

const router = require("./src/routers/router")(app);

app.use("/", router);

//app.get("/", (req, res)=> res.send("서버 연동") );

app.set("views", __dirname+"/src/views");
app.set("view engine","ejs");

app.listen(3000, ()=>{ console.log("3000 서버 연동"); });

--router.js

module.exports = (app)=>{
    const pageRouter = require("../routers/mesm_router");
    app.use("/", pageRouter );

    const router = require("express").Router();
    const config = require("../../config/cookie_session/cookie_session_config")
    router.get("/", (req, res)=>{
        if(req.session.username){
            res.cookie('isLogin',true);
        }
        res.render("index", {username : req.session.username });

    })
    
    return router;
}
    

--mesm_router.js

const router = require("express").Router();
const mesmCtrl = require("../controller/mesm_ctrl");

//router.get("/",mesmCtrl.views.index);
router.get("/login", mesmCtrl.views.login);
router.post("/login_check", mesmCtrl.process.loginCheck);

router.get("/main",mesmCtrl.views.main);

module.exports = router;

--controller.js

const ser = require("../service/mesm_service");

const views = {
    index : (req, res) =>{
        res.render("index");
    },
    login :(req,res)=>{
        res.render("member/login",
        {username : req.session.username});
    },
    main : (req,res)=>{
        res.render("member/main");
    },
    
}

const process = {
    loginCheck : async (req,res) =>{
        const msgPack = await ser.loginCheck( req.body );
        if( msgPack.result === 0){
            req.session.username = req.body.id;
        }
        res.send(msgPack.msg );
    },
    
}

module.exports = {views, process};

회원가입 기능과 로그인 기능을 구현해서
회원가입 하면 db에 값이 저장되고 로그인하면 db에 있는 값을 불러와서
로그인까진 되는데 쿠키세션이 실행되지 않습니다,,
코드가 잘못된건지 계속 뭘 건드려도 쿠키값이 저장되지 않네요