How to get websocket url (subscripionsUrl) from apolloserver constructor - websocket

Question

I have this code and i try to charge the subscription in apollo playground but i cant it, I also tried to import 'PubSub' from apollo-server but this didn't work, I also tried to follow the documentation but it gave the same result, I have been reading in many places but no solutions; I must emphasize that the subscriptionsUrl returns me undefined and according to what I investigate it should be something like 'ws://...',
not if my code is a bit old or what happens
i'm trying make the subscription executed in loop but i receive the response
{
"message": "server must support graphql-ws or subscriptions-transport-ws protocol"
}
the typeDefs and resolvers is declared in the same file that server variable, does anyone know what to do?
import * as dotenv from 'dotenv'
dotenv.config()
import './mongo.js'
import {
ApolloServer,
AuthenticationError,
gql,
UserInputError
} from 'apollo-server'
import { PubSub } from 'graphql-subscriptions'
import Person from './models/person.js'
import User from './models/user.js'
import jwt from 'jsonwebtoken'
const { JWT_SECRET } = process.env
const SUBS_EVENTS = {
PERSON_ADDED: 'PERSON_ADDED'
}
const pubsub = new PubSub()
const typeDefs = gql`...`
const resolvers = {...}
const server = new ApolloServer({
typeDefs,
resolvers,
context: async ({ req }) => {
const auth = req ? req.headers.authorization : null
if (auth && auth.toLowerCase().startsWith(`bearer `)) {
const token = auth.substring(7)
const { id } = jwt.verify(token, JWT_SECRET)
const currentUser = await User.findById(id).populate('friends')
return { currentUser }
}
}
})
server.listen().then(({ url, subscriptionsUrl }) => {
console.log(`Server ready at ${url}`)
console.log(`Subscriptions ready at ${subscriptionsUrl}`)
})
// in the json
{
"name": "graphql-server",
"version": "1.0.0",
"description": "",
"type": "module",
"main": "index.js",
"scripts": {
"jsonserver": "json-server --watch db.json",
"test": "echo \"Error: no test specified\" && exit 1"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"apollo-server": "3.10.3",
"axios": "1.1.3",
"dotenv": "16.0.3",
"express": "^4.18.2",
"graphql": "^16.6.0",
"graphql-subscriptions": "^2.0.0",
"jsonwebtoken": "8.5.1",
"mongoose": "6.7.0",
"mongoose-unique-validator": "3.1.0",
"uuid": "9.0.0"
},
"devDependencies": {
"json-server": "0.17.0"
}
}