RSS Feed to Google Chat Webhook using Cloud Functions for Firebase and Superfeedr

Paul Kinlan
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We use Google Chat internally a lot to communicate across our team - it’s kinda like our slack; We also create a lot of content that is accessible via RSS feeds, we even have a team feed that you can all view. It wasn’t until recently that I found out that it was pretty easy to create a simple post-only bot via WebHooks and that gave me the idea, I can create a simple service that polls RSS feeds and then sends them to our webhook that can post directly in to our team chat.

It was pretty simple in the end, and I’ve included all the code below. I used Firebase functions - I suspect that this is just as easy on other Function-as-a-service sites - and Superfeedr. Superfeedr is a service that can listen to Pubsubhubbub pings (now WebSub) and it will also poll RSS feeds that don’t have Pubsub set up. Then when it finds a feed it will ping a configured URL (in my case my Cloud Function in Firebase) with an XML or JSON representation of the newly found feed data - all you have to do is parse the data and do something with it.

const functions = require('firebase-functions');
const express = require('express');
const cors = require('cors');
const fetch = require('node-fetch');
const app = express();

// Automatically allow cross-origin requests
app.use(cors({ origin: true }));

app.post('/', (req, res) => {
  const { webhook_url } = req.query;
  const { body } = req;
  if (body.items === undefined || body.items.length === 0) {
    res.send('');
    return;
  }

  const item = body.items[0];
  const actor = (item.actor && item.actor.displayName) ? item.actor.displayName : body.title;

  fetch(webhook_url, {
    method: 'POST',
    headers: {
      "Content-Type": "application/json; charset=utf-8",
    },
    body: JSON.stringify({
      "text": `*${actor}* published <${item.permalinkUrl}|${item.title}>. Please consider <https://twitter.com/intent/tweet?url=${encodeURIComponent(body.items[0].permalinkUrl)}&text=${encodeURIComponent(body.items[0].title)}|Sharing it>.`
    })  
  }).then(() => {
    return res.send('ok');
  }).catch(() => {
    return res.send('error')
  });
})
// Expose Express API as a single Cloud Function:
exports.publish = functions.https.onRequest(app);

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I was surprised and delighted about how easy it was to set up.

Paul Kinlan

Trying to make the web and developers better.

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