Cloud Functions

Cloud Functions runs short, event-driven Node.js handlers triggered by HTTP, Pub/Sub, Cloud Storage, or Firestore events. Gen 2 builds on Cloud Run, so you get concurrency settings and longer timeouts while keeping a function-centric deploy model.

					import functions from '@google-cloud/functions-framework';

functions.http('webhook', async (req, res) => {
  const eventId = req.get('x-event-id');
  if (!eventId) {
    res.status(400).send('missing event id');
    return;
  }
  await processWebhook(req.body, { eventId });
  res.status(204).send();
});
				

| Trigger | Typical FullStack use | |---------|----------------------| | HTTP | Webhooks and lightweight APIs | | Pub/Sub | Async workers reacting to domain events | | Storage | Image processing after user upload |

Keep handlers idempotent, finish within timeout, and push heavy work to queues or Cloud Run services.

On interviews: Functions versus Cloud Run; cold starts; idempotency with at-least-once delivery; IAM on invokers; environment secrets via Secret Manager.

Common pitfalls: long CPU work inside one invocation; relying on in-memory state between calls; logging secrets; unbounded retries on poison messages.

The trade-off is fast event glue code versus tight runtime limits and harder local parity for complex services.

Checklist:

• Design handlers to be idempotent and stateless.
• Offload long jobs to Pub/Sub consumers or Cloud Run jobs.
• Scope IAM to specific triggers and service accounts.
• Load secrets from Secret Manager, not env files in repo.