Firebase functions ENOTFOUND on all http requests

I'm trying to set up a function that uses Express and makes HTTP requests, but I always get an ENOTFOUND error, no matter the request I make.

I already tried making the requests using 4 different libraries (https, request, request-promise, requestify), but all give the same error.

I followed this examples to set up the system: minimal-webhook + authorized-https-endpoint.

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My basic test function, that also throws the error:

"use strict";
const functions = require("firebase-functions");
const admin = require("firebase-admin");
admin.initializeApp(functions.config().firebase);

const express = require("express");
const app = express();

const https = require("https");

app.get("*", (req, res) =>
{
    var testReq = https.request({
        host: "www.google.com",
        path: "/recaptcha/api/siteverify"
    },

    (res) => {
        console.log("Finished with response " + res);
    });

    testReq.on("error", (e) => {
        console.log("Crashed with error " + e);
    });

    testReq.end();
});

exports.test = functions.https.onRequest(app);

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Log of GET request to https://us-central1-project-abc.cloudfunctions.net/test/ using Postman, for example:

Crashed with error Error: getaddrinfo ENOTFOUND www.google.com www.google.com:443

via Sergio Carneiro