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  • Sem Tadema
    Sem TademaCTO

This post is a dedicated deep dive into ServerlessFunction in Caraer apps and how it connects to webhook delivery.

What a ServerlessFunction is

ServerlessFunction is linked to an App.

Core fields:

  • runtime
  • code
  • description

Supported runtimes

Current allowed runtimes are:

  • nodejs22
  • python312

Validation rejects values outside that allowlist.

Deployment behavior on save

This means save operations are operationally significant: they can provision or update cloud infrastructure.

How this integrates with webhooks

Webhooks can link to a serverless function through USES_SERVERLESS_FUNCTION.

Typical pattern:

  1. Define serverless function in the app.
  2. Reference that function in webhook configuration.
  3. Use webhook delivery mode and filters to control invocation behavior.

When to use serverless function delivery

Use serverless when you need:

  • low-latency processing close to event trigger
  • lightweight transformation/enrichment before forwarding
  • internal execution without exposing public webhook endpoints

Use HTTP webhook delivery when you need centralized integration handling in your own backend.

Operational checklist

  • Keep function code idempotent.
  • Guard against retries/duplicate webhook events.
  • Version function behavior carefully across app updates.
  • Monitor cloud function logs and failure rates.