Using Cloud Storage for Firebase for hosting rich media in your Actions

index.js

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
const bucket = admin.storage().bucket();
const bucketAccessConfig = {
  action: 'read',
  expires: Date.now() + 1000 * 60 * 60
};

const {dialogflow} = require(‘actions-on-google’);

const app = new dialogflow();

app.intent('ssml response', async conv => {
    const soundFileRef = bucket.file('audio/sound-effect.mp3');
    const [soundUrl] = await soundFileRef.getSignedUrl(bucketAccessConfig);

    conv.ask(`<speak>I can return some text, then a sound effect.
            <audio src="${soundUrl}"></audio>
            </speak>`);
});

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