Retool to GCP Pub/Sub

Retool is great as a no/low code solution for building apps. Although their catalogue of “off the shelf” resources is growing (and includes more and more Google Cloud Platform resources), there’s still a few key resources missing, such as a native Pub/Sub resource (AWS SNS is there, if this is your jam).

It’s possible to get up and running with Retool using a Service Account to authenticate over the Google Cloud REST API in a matter of minutes. I couldn’t find a guide for this anywhere so I’m writing one, just in case this helps anyone else.

Start in Google Cloud Console by creating a service account with the role Pub/Sub Publisher (following the principles of least privilege), generate a JSON key and store that safely somewhere.

Then hop over to Retool and create a new REST API resource, I called mine GCP Pub/Sub. Set the Base URL as https://pubsub.googleapis.com/v1 and under Authentication select Google Service Account. Paste in your JSON key (this will be stored, encrypted, on Retool) and under Service Account OAuth Scopes add https://www.googleapis.com/auth/pubsub.

Then you’re pretty much all set to interact with the Pub/Sub REST API. For example if you’d like to publish a message, create a new Retool query from the GCP Pub/Sub resource which looks like this following:

Field	Value
Method	POST
URL	projects/{your project ID}/topics/{your topic name}:publish
Headers	Content-type: application/json
Body (Raw)	{"messages": [{"data": {{ btoa(payload) }}}]}

You’ll get a squiggly line under payload (Retool has this barely documented feature where queries can take placeholder parameters), but the idea here is we use btoa() to base64 encode the payload, which we pass in from somewhere else.

Then you can use this query wherever in Retool you can write a JS script (this is used as an “Action” on a table to send the raw row to Pub/Sub):

await myPubSubQuery.trigger({
  additionalScope: {
    payload: JSON.stringify({
      ...currentSourceRow,
      foo: 'bar',
    }),
  },
});

In the Response tab of your query, make sure to tick Show notification on Success so that your Retool app users know everything worked!