Secure an azure function http trigger with passport azure-ad

How can I protect azure function using the passport and passport-azure-ad I don't want to protect all of the azure functions, some functions will require an access_token to be validated before running the code. And most of the samples i found online are using express, which cannot be used in azure functions.

I tried the below approach but the code still ran without authentication.

const passport = require("passport");
const config = require("../shared/config");
const createMongoClient = require("../shared/mongo");
const BearerStrategy = require("passport-azure-ad").BearerStrategy;

const bearerStrategy = new BearerStrategy(config, function (token, done) {
  // Send user info using the second argument
  done(null, {}, token);
});
passport.use(bearerStrategy);
passport.initialize();

module.exports = async function (context, req) {
  passport.authenticate("oauth-bearer", { session: false });
  const dish = req.body || {};

  if (dish) {
    context.res = {
      status: 400,
      body: "Dish data is required! ",
    };
  }

  const { db, connection } = await createMongoClient();

  const Dishes = db.collection("dishes");

  try {
    const dishes = await Dishes.insertOne(dish);
    connection.close();

    context.res = {
      status: 201,
      body: dishes.ops[0],
    };
  } catch (error) {
    context.res = {
      status: 500,
      body: "Error creating a new Dish",
    };
  }
};