temporalio__skill-temporal-developer/references/ruby/ruby.md

Temporal Ruby SDK Reference

Overview

The Temporal Ruby SDK (temporalio gem) provides a class-based approach to building durable workflows. Ruby 3.3+ required. Workflows run using a Durable Fiber Scheduler for determinism protection, with Illegal Call Tracing via TracePoint to detect non-deterministic operations.

Quick Demo of Temporal

Add Dependency on Temporal: Add temporalio to your Gemfile or install directly with gem install temporalio.

say_hello_activity.rb - Activity definition:

require 'temporalio/activity'

class SayHelloActivity < Temporalio::Activity::Definition
  def execute(name)
    "Hello, #{name}!"
  end
end

say_hello_workflow.rb - Workflow definition:

require 'temporalio/workflow'

class SayHelloWorkflow < Temporalio::Workflow::Definition
  def execute(name)
    Temporalio::Workflow.execute_activity(
      SayHelloActivity,
      name,
      schedule_to_close_timeout: 30
    )
  end
end

worker.rb - Worker setup (imports activity and workflow, runs indefinitely and processes tasks):

require 'temporalio/client'
require 'temporalio/worker'
require_relative 'say_hello_activity'
require_relative 'say_hello_workflow'

# Create client connected to server at the given address
# This is the default port for `temporal server start-dev`
client = Temporalio::Client.connect('localhost:7233', 'default')

# Create and run the worker
worker = Temporalio::Worker.new(
  client: client,
  task_queue: 'my-task-queue',
  workflows: [SayHelloWorkflow],
  activities: [SayHelloActivity]
)
worker.run

Start the dev server: Start temporal server start-dev in the background.

Start the worker: Start ruby worker.rb in the background.

execute_workflow.rb - Start a workflow execution:

require 'temporalio/client'
require 'securerandom'
require_relative 'say_hello_workflow'

# Create client connected to server at the given address
client = Temporalio::Client.connect('localhost:7233', 'default')

# Execute a workflow
result = client.execute_workflow(
  SayHelloWorkflow,
  'my name',
  id: SecureRandom.uuid,
  task_queue: 'my-task-queue'
)

puts "Result: #{result}"

Run the workflow: Run ruby execute_workflow.rb. Should output: Result: Hello, my name!.

Key Concepts

Workflow Definition

• Subclass Temporalio::Workflow::Definition
• Define def execute(args) as the entry point
• Use Temporalio::Workflow.execute_activity to call activities
• Define signals, queries, and updates via class-level DSL methods

Activity Definition

• Subclass Temporalio::Activity::Definition
• Define def execute(args) as the entry point
• Activities contain all non-deterministic and side-effectful code
• Can access Temporalio::Activity::Context.current for heartbeating

Worker Setup

• Connect client with Temporalio::Client.connect
• Create worker with Temporalio::Worker.new(client:, task_queue:, workflows:, activities:)
• Run with worker.run

Determinism

Workflow code must be deterministic! The Ruby SDK uses a Durable Fiber Scheduler and Illegal Call Tracing (via Ruby's TracePoint) to detect non-deterministic operations at runtime. All sources of non-determinism should either use Temporal-provided alternatives or be defined in Activities. Read references/core/determinism.md and references/ruby/determinism.md to understand more.

File Organization Best Practice

Keep Workflow definitions in separate files from Activity definitions. Unlike Python, Ruby does not have a sandbox reloading concern, but separating workflows and activities is still good practice for clarity and maintainability. Use require_relative to import between files.

my_temporal_app/
├── workflows/
│   └── say_hello_workflow.rb   # Only Workflow classes
├── activities/
│   └── say_hello_activity.rb   # Only Activity classes
├── worker.rb                   # Worker setup, requires both
└── execute_workflow.rb          # Client code to start workflows

Common Pitfalls

1. Using sleep instead of Temporalio::Workflow.sleep - Standard sleep is non-deterministic and will be flagged by Illegal Call Tracing; use the Temporal-provided version
2. Using Time.now instead of Temporalio::Workflow.now - Same issue; Time.now is non-deterministic in workflow context
3. Third-party gems triggering illegal calls - Gems that perform I/O, use threads, or call system time will be caught by TracePoint tracing; move that logic to activities
4. Using puts/Logger in workflows - Use Temporalio::Workflow.logger instead for replay-safe logging
5. Not heartbeating long activities - Long-running activities need Temporalio::Activity::Context.current.heartbeat
6. Mixing Workflows and Activities in same file - Bad structure; keep them separated for clarity

Writing Tests

See references/ruby/testing.md for info on writing tests.

Additional Resources

Reference Files

• references/ruby/patterns.md - Signals, queries, child workflows, saga pattern, etc.
• references/ruby/determinism.md - Durable Fiber Scheduler behavior, safe alternatives, history replay
• references/ruby/determinism-protection.md - Illegal Call Tracing via TracePoint, forbidden operations, runtime detection
• references/ruby/versioning.md - Patching API, workflow type versioning, Worker Versioning
• references/ruby/testing.md - Test environments, time-skipping, activity mocking
• references/ruby/error-handling.md - ApplicationError, retry policies, non-retryable errors, idempotency
• references/ruby/data-handling.md - Data converters, payload encryption
• references/ruby/observability.md - Logging, metrics, tracing, Search Attributes
• references/ruby/gotchas.md - Ruby-specific mistakes and anti-patterns
• references/ruby/advanced-features.md - Schedules, worker tuning, and more