How to create a session cookie for persistent login in Firebase? - firebase

Question

I've been going over Manage Session Cookies to get a better understanding of how firebase auth works. However I have run into some trouble when it comes to implementing cookies. I have been able to successfully follow the example up to the section labeled sign-in but have been unable to follow the next step where I generate my session cookie.
I would like to use my cookie as a jwt in order to do checks on users making request to my endpoints and trying to access my site. However I am unable to actually generate a cookie and am unsure why. The syntax is a bit confusing for me because I am using express while they are not.
So to clarify I believe that I have correctly set up my code but due to the fact that I have not been able to create a token I must not have. Also note that I am not doing the csrf step and will come back for that later and am mainly concerned with generating my token. If anyone can point out why my token might not be generating or point me in the right direction I would be grateful.
Code:
import functions from 'firebase-functions'
import { initializeApp } from 'firebase/app';
import { getAuth, getIdToken, signInWithEmailAndPassword } from "firebase/auth";
import express from 'express';
import cors from 'cors';
import pool from './db.js';
import cookies from "cookie-parser";
const firebaseConfig = {
apiKey: process.env.FB_APIKEY,
authDomain: process.env.FB_AUTHDOMAIN,
projectId: process.env.FB_PROJECTID,
storageBucket: process.env.FB_STORAGEBUCKET,
messagingSenderId: process.env.FB_MESSAGINGSENDERID,
appId: process.env.FB_APPID,
measurementId: process.env.FB_MEASUREMENTID,
};
const app = express();
const firebaseApp = initializeApp(firebaseConfig)
const auth = getAuth()
app.use(cors({origin:true}));
app.use(express.json());
app.use(cookies());
app.get('/firebaseLogin/:body',async(req,res)=>{
let {body} = req.params
body = JSON.parse(body)
const expiresIn = 60 * 60 * 24 * 5 * 1000;
try{
let signInAttempt = await signInWithEmailAndPassword(auth,body.user,body.pass)
let idToken = await getIdToken(signInAttempt.user) // Grabs user token after sign in is approved
getAuth()
.createSessionCookie(idToken, { expiresIn })
.then(
(sessionCookie) => {
// Set cookie policy for session cookie.
const options = { maxAge: expiresIn, httpOnly: true, secure: true };
res.cookie('session', sessionCookie, options);
res.end(JSON.stringify({ status: 'success' }));
},
(error) => {
res.status(401).send('UNAUTHORIZED REQUEST!');
}
);
}catch(error){
res.json(error)
}
})