Trigger Cloudflare Workers from database changes

1. Log in to your Cloudflare dashboard and navigate to the “Workers and Pages” section.
2. Click on “Create Worker”.
3. Give your service a name (e.g., “user-worker”) and click “Deploy”.

Cloudflare will create a new worker.

Click the Edit code button.

Replace the default code in the worker editor with the following:

export default {
  async fetch(request, env) {
    // Verify the Sequin webhook secret
    const authHeader = request.headers.get('authorization');
    if (!authHeader || authHeader !== `Bearer ${env.SEQUIN_WEBHOOK_SECRET}`) {
      return new Response('Unauthorized', { status: 401 });
    }

    try {
      const payload = await request.json();
      const { record } = payload;

      if (record && record.name) {
        console.log(`Hello ${record.name}`);
      } else {
        console.log('No name found in the payload.');
      }

      return new Response('Success', { status: 200 });
    } catch (error) {
      console.error('Error processing request:', error);
      return new Response('Internal Server Error', { status: 500 });
    }
  },
};

This worker first checks the authorization header to make sure the request is coming from Sequin. Then it processes the payload and logs a message to the console. In this example code, the row that changed contains a name field, so the worker logs the name to the console.

Click the Deploy button to deploy your worker.

1. In your worker’s settings, go to the “Settings” tab.
2. Scroll down to the “Variables and Secrets” section.
3. Click ”+ Add”.
4. Set the variable name as SEQUIN_WEBHOOK_SECRET and the value to a secure secret of your choice.
5. Click “Deploy”.

Keep this secret handy. You will need to use this secret value in the Sequin dashboard when you create the push consumer.

Under the “Settings” tab, find the “Domains & Routes” section.

Copy the worker’s URL. You will need this URL in the Sequin dashboard when you create the push consumer.

Navigate to the “Sinks” tab, click the “Create Sink” button, and select “Webhook Sink”.

Select the schemas and tables you want to capture changes from (i.e public.users or public).

Add filters to the sink to control which database changes are sent to your webhook endpoint.

You can optionally indicate if you want your webhook endpoint to receive a backfill of all or a portion of the table’s existing data. For now, leave “Backfill” toggled off.

Under “Message grouping”, leave the default option selected to ensure events for the same row are sent to your webhook endpoint in order.

Under “Webhook Sink configuration” leave the defaults:

• Leave the default value of 30000 ms for “Request timeout” as this is more than enough time for your worker to process the request
• Leave the default value of 1 for “Batch size” so each change is processed individually.

Under “HTTP Endpoint”, enter the Cloudflare Worker’s URL you copied earlier. Then click to “Add Encrypted Header” with the key Authorization and the value Bearer SEQUIN_WEBHOOK_SECRET, using the secret value you set in your worker’s environment variables.

Give your sink a name (i.e. users_webhook_sink) and click “Create Webhook Sink”.

For example, insert a row into the users table:

insert into
users (name)
values
  (
    'John Doe'
  );

In the Sequin console, open the Messages tab on your webhook sink and confirm that a message was delivered.

1. Go to your Cloudflare dashboard and navigate to your worker.
2. Click on the “Logs” tab.
3. You should see a log entry. For example:Hello John Doe: