# Cloud Tasks, Cloud Scheduler and Workflows — Google Cloud Platform

Source: https://www.skillbyai.com/en/gcp/s-orchestration

> Schedule jobs, queue work to an endpoint and orchestrate multi-step processes.

## Three helpers for background work

**Cloud Scheduler** is managed cron: on a schedule it calls an HTTP endpoint, publishes to Pub/Sub or triggers a workflow, for example to start a nightly Cloud Run job. **Cloud Tasks** is a queue of individual tasks delivered to an HTTP endpoint with **rate limits**, retries with backoff and scheduled delivery times; use it when *you* want to control how fast a downstream service is called, such as sending emails at 10 per second. Compare with Pub/Sub, where publishers do not control delivery and many subscribers can receive the same event. **Workflows** orchestrates steps defined in YAML: call services and APIs in order, branch, loop, wait, handle errors and retries, keeping state between steps without you running a server.

## A small workflow

Validate an order, charge it, and notify, with a retry policy on the payment call.

```yaml
main:
  params: [order]
  steps:
    - validate:
        call: http.post
        args:
          url: https://orders-api-xyz.a.run.app/validate
          body: ${order}
          auth: { type: OIDC }
        result: validation
    - charge:
        try:
          call: http.post
          args:
            url: https://payments-xyz.a.run.app/charge
            body: ${order}
            auth: { type: OIDC }
          result: payment
        retry: ${http.default_retry}
    - notify:
        call: googleapis.pubsub.v1.projects.topics.publish
        args:
          topic: projects/shop-dev-123456/topics/order-paid
          body:
            messages:
              - data: ${base64.encode(json.encode(order))}
    - done:
        return: ${payment.body}
```

## Pick by who controls the pace

Fan-out of events: Pub/Sub. Rate-limited calls to one service: Cloud Tasks. Run at a time: Cloud Scheduler. A multi-step process with branching and retries: Workflows.

**Quiz:** You must call a partner API for each signup but never exceed 5 calls per second. Which service fits best?

- [x] Cloud Tasks
- [ ] Cloud Scheduler
- [ ] Pub/Sub with many subscriptions
- [ ] Cloud Storage

*Answer:* Cloud Tasks. Cloud Tasks queues individual tasks to an endpoint with configurable dispatch rate limits.