Error database connect is not a function Nodejs with Mysql in docker

I have deployed my docker application (to DigitalOcean). Everything work's, but I can't connect mysql with nodejs.

When I run docker-compose up I get error database.connect is not a function.

My server.js file is look like this

const mysql = require("mysql");

const database = mysql.createPool({
    host: process.env.MYSQL_HOST_IP,
    user: "db_user",
    password: "db_user_pass",
    database: "guess-game",
    port: 3306,
});

database.connect((err) => {
    if (err) {
        console.error("error connecting: " + err.stack);
        return;
    }
    console.log("connected as id " + db.threadId);
});

module.exports = db;

I don't know what I need to write this line to make it work.

host: process.env.MYSQL_HOST_IP,

I tried to add droplet IP as host, but this is also don't work.

host: "http://46.101.162.111/",

Also, I try this.

host: "46.101.162.111",

My docker-compose.yml file

version: "3"

networks:
  dbnet:

services:
  phpmyadmin: 
    image: phpmyadmin/phpmyadmin
    container_name: phpmyadmin1
    environment: 
      - PMA_ARBITRARY=1
      - PMA_HOST=db
    restart: always
    links:
      - db
    ports: 
      - 8899:80
    depends_on:
      - db
    networks:
      - dbnet

  api:
    build: ./api
    container_name: api1
    command: npm run start
    restart: unless-stopped
    ports:
      - "3005:3005"
    environment: 
      - PORT=3005
      - MYSQL_HOST_IP=172.18.0.2
    depends_on:
      - phpmyadmin
    networks:
      - dbnet

  db: 
    image: mysql:latest
    container_name: db
    command: --default-authentication-plugin=mysql_native_password
    environment:
      - MYSQL_ROOT_PASSWORD=my_secret_password
      - MYSQL_DATABASE=guess-game
      - MYSQL_USER=db_user
      - MYSQL_PASSWORD=db_user_pass
    restart: always
    ports: 
      - 6033:3306
    networks:
      - dbnet

Struggling almost 3 days. 😣