Workflows

Google Cloud Workflows is a fully managed orchestration service that lets you execute multi-step workflows by combining Google Cloud services, APIs, and custom code. Unlike event-driven, fire-and-forget patterns, Workflows provides a durable, stateful execution engine that tracks progress, handles errors, and supports long-running processes.

---

What Are Workflows?

Workflows lets you define a series of steps — calling APIs, running Cloud Functions, invoking Cloud Run services, waiting for events, and performing logic — in a declarative YAML or JSON format. The Workflows engine executes each step, manages state, handles retries, and provides observability.

Key Characteristics

Characteristic	Description
Fully managed	No servers, clusters, or infrastructure to manage
Durable execution	State is persisted — workflows survive infrastructure failures
Long-running	Workflows can run for up to one year
Serverless pricing	Pay per step executed (first 5,000 steps/month free)
Built-in error handling	Try/catch, retry policies, and custom error handling
Connectors	Pre-built connectors for 20+ Google Cloud services

---

Workflow Structure

A workflow is defined as a series of steps. Each step performs an action — calling an HTTP endpoint, assigning variables, evaluating conditions, or iterating over data.

# A simple workflow that calls a Cloud Function and processes the result
main:
  steps:
    - get_data:
        call: http.get
        args:
          url: https://europe-west2-my-project.cloudfunctions.net/getData
          auth:
            type: OIDC
        result: api_response

    - check_status:
        switch:
          - condition: \${api_response.body.status == "ready"}
            next: process_data
          - condition: \${api_response.body.status == "pending"}
            next: wait_and_retry
        next: handle_error

    - process_data:
        call: http.post
        args:
          url: https://my-service-xyz.run.app/process
          auth:
            type: OIDC
          body:
            data: \${api_response.body.records}
        result: process_result

    - wait_and_retry:
        call: sys.sleep
        args:
          seconds: 30
        next: get_data

    - handle_error:
        raise:
          code: 500
          message: "Unexpected status"

---

Step Types

Workflows supports several step types for building complex logic:

HTTP Calls

Call any HTTP endpoint — Google Cloud APIs, Cloud Run services, Cloud Functions, or external APIs.

- call_api:
    call: http.get
    args:
      url: https://api.example.com/data
      headers:
        Authorization: "Bearer my-token"
      query:
        limit: 100
    result: response

Variable Assignment

Store and manipulate data between steps.

- assign_vars:
    assign:
      - name: "Cloud Functions"
      - count: 42
      - items: [1, 2, 3]

Conditional Logic

Branch workflow execution based on conditions.

- check_count:
    switch:
      - condition: \${count > 100}
        next: high_volume
      - condition: \${count > 10}
        next: medium_volume
    next: low_volume