Go Client SDK

Introduction

The Cadence Go SDK is the official client library for building workflows and activities in Go. It provides a type-safe, idiomatic Go API for defining durable workflows that can run for days, months, or years.

GitHub Repository

Official Cadence Go Client SDK - Star and contribute on GitHub

Installation

Prerequisites

Go 1.18 or higher
Cadence server running (local or remote)

Add Dependency

go get go.uber.org/cadence

Import Packages

import (
    "go.uber.org/cadence/client"
    "go.uber.org/cadence/worker"
    "go.uber.org/cadence/workflow"
    "go.uber.org/cadence/activity"
)

Quick Start

1. Define a Workflow

Workflows must be deterministic and cannot directly call external services:

package main

import (
    "time"
    "go.uber.org/cadence/workflow"
)

// HelloWorkflow is a simple workflow that calls an activity
func HelloWorkflow(ctx workflow.Context, name string) (string, error) {
    // Configure activity options
    ao := workflow.ActivityOptions{
        ScheduleToStartTimeout: time.Minute,
        StartToCloseTimeout:    time.Minute,
        HeartbeatTimeout:       time.Second * 20,
    }
    ctx = workflow.WithActivityOptions(ctx, ao)

    // Execute activity
    var result string
    err := workflow.ExecuteActivity(ctx, GreetingActivity, name).Get(ctx, &result)
    if err != nil {
        return "", err
    }

    return result, nil
}

2. Define an Activity

Activities perform the actual work and can call external services:

package main

import (
    "context"
    "fmt"
)

// GreetingActivity is an activity that generates a greeting
func GreetingActivity(ctx context.Context, name string) (string, error) {
    // Activities can call external services, databases, etc.
    return fmt.Sprintf("Hello, %s!", name), nil
}

3. Start a Worker

Workers poll for tasks and execute workflows and activities:

package main

import (
    "go.uber.org/cadence/client"
    "go.uber.org/cadence/worker"
    "go.uber.org/zap"
)

func main() {
    // Create Cadence client
    logger, _ := zap.NewDevelopment()
    
    cadenceClient, err := client.NewClient(client.Options{
        HostPort:     "localhost:7933",
        Domain:       "my-domain",
        MetricsScope: nil, // Optional: add metrics
    })
    if err != nil {
        logger.Fatal("Failed to create client", zap.Error(err))
    }
    defer cadenceClient.Close()

    // Configure worker options
    workerOptions := worker.Options{
        Logger: logger,
        MetricsScope: nil,
        MaxConcurrentActivityExecutionSize:     100,
        MaxConcurrentDecisionTaskExecutionSize: 50,
    }

    // Create worker
    cadenceWorker := worker.New(cadenceClient, "my-task-list", workerOptions)

    // Register workflows
    cadenceWorker.RegisterWorkflow(HelloWorkflow)

    // Register activities
    cadenceWorker.RegisterActivity(GreetingActivity)

    // Start worker
    err = cadenceWorker.Start()
    if err != nil {
        logger.Fatal("Failed to start worker", zap.Error(err))
    }

    // Wait indefinitely
    select {}
}

4. Execute a Workflow

Start workflow execution from your application:

package main

import (
    "context"
    "time"
    "go.uber.org/cadence/client"
)

func executeWorkflow() {
    // Create client
    cadenceClient, err := client.NewClient(client.Options{
        HostPort: "localhost:7933",
        Domain:   "my-domain",
    })
    if err != nil {
        panic(err)
    }
    defer cadenceClient.Close()

    // Configure workflow options
    workflowOptions := client.StartWorkflowOptions{
        ID:                           "hello-workflow-1",
        TaskList:                     "my-task-list",
        ExecutionStartToCloseTimeout: time.Minute * 10,
        DecisionTaskStartToCloseTimeout: time.Minute,
    }

    // Start workflow
    we, err := cadenceClient.ExecuteWorkflow(
        context.Background(),
        workflowOptions,
        HelloWorkflow,
        "World",
    )
    if err != nil {
        panic(err)
    }

    // Wait for result
    var result string
    err = we.Get(context.Background(), &result)
    if err != nil {
        panic(err)
    }

    println("Workflow result:", result)
}

Advanced Patterns

Child Workflows

Orchestrate complex processes by composing workflows:

func ParentWorkflow(ctx workflow.Context) error {
    childOptions := workflow.ChildWorkflowOptions{
        ExecutionStartToCloseTimeout: time.Hour,
        TaskList:                     "child-task-list",
    }
    ctx = workflow.WithChildOptions(ctx, childOptions)

    var result string
    err := workflow.ExecuteChildWorkflow(ctx, ChildWorkflow, "input").Get(ctx, &result)
    if err != nil {
        return err
    }

    return nil
}

Signals and Queries

Signals
Queries

Signals allow external systems to send commands to running workflows:

func SignalableWorkflow(ctx workflow.Context) error {
    var message string
    signalChan := workflow.GetSignalChannel(ctx, "message-signal")
    
    // Wait for signal
    signalChan.Receive(ctx, &message)
    
    workflow.GetLogger(ctx).Info("Received signal", "message", message)
    return nil
}

// Send signal from client
err = cadenceClient.SignalWorkflow(
    context.Background(),
    "workflow-id",
    "run-id",
    "message-signal",
    "Hello from signal",
)

Queries allow external systems to read workflow state without modifying it:

func QueryableWorkflow(ctx workflow.Context) error {
    counter := 0
    
    // Register query handler
    err := workflow.SetQueryHandler(ctx, "counter", func() (int, error) {
        return counter, nil
    })
    if err != nil {
        return err
    }
    
    // Workflow logic...
    counter++
    
    return nil
}

// Query from client
resp, err := cadenceClient.QueryWorkflow(
    context.Background(),
    "workflow-id",
    "run-id",
    "counter",
)
var result int
resp.Get(&result)

Error Handling and Retries

func RobustWorkflow(ctx workflow.Context) error {
    // Configure retry policy
    retryPolicy := &workflow.RetryPolicy{
        InitialInterval:    time.Second,
        BackoffCoefficient: 2.0,
        MaximumInterval:    time.Minute,
        MaximumAttempts:    5,
        NonRetriableErrorReasons: []string{"invalid-input"},
    }

    ao := workflow.ActivityOptions{
        StartToCloseTimeout: time.Minute * 5,
        RetryPolicy:         retryPolicy,
    }
    ctx = workflow.WithActivityOptions(ctx, ao)

    // Execute activity with automatic retries
    err := workflow.ExecuteActivity(ctx, RiskyActivity).Get(ctx, nil)
    if err != nil {
        // Handle error or let workflow fail
        return err
    }

    return nil
}

Local Activities

Local activities are optimized for short, fast operations:

func WorkflowWithLocalActivity(ctx workflow.Context) error {
    lao := workflow.LocalActivityOptions{
        ScheduleToCloseTimeout: time.Second * 5,
    }
    ctx = workflow.WithLocalActivityOptions(ctx, lao)

    // Execute local activity (no history event)
    var result string
    err := workflow.ExecuteLocalActivity(ctx, FastActivity).Get(ctx, &result)
    if err != nil {
        return err
    }

    return nil
}

Worker Configuration

Tuning Worker Performance

workerOptions := worker.Options{
    Logger:       logger,
    MetricsScope: metricsScope,
    
    // Control concurrent workflow executions
    MaxConcurrentDecisionTaskExecutionSize: 100,
    
    // Control concurrent activity executions
    MaxConcurrentActivityExecutionSize: 200,
    
    // Control poller threads
    MaxConcurrentActivityTaskPollers: 10,
    MaxConcurrentDecisionTaskPollers: 5,
    
    // Enable sticky workflow cache for performance
    EnableStickyExecution: true,
    StickyScheduleToStartTimeout: time.Second * 5,
}

Worker Lifecycle Management

func runWorkerWithGracefulShutdown() {
    cadenceWorker := worker.New(cadenceClient, "my-task-list", workerOptions)
    
    // Register workflows and activities
    cadenceWorker.RegisterWorkflow(MyWorkflow)
    cadenceWorker.RegisterActivity(MyActivity)
    
    // Start worker
    err := cadenceWorker.Start()
    if err != nil {
        panic(err)
    }
    
    // Handle shutdown signals
    sigChan := make(chan os.Signal, 1)
    signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
    <-sigChan
    
    // Graceful shutdown
    cadenceWorker.Stop()
}

Testing

Unit Testing Workflows

import (
    "testing"
    "go.uber.org/cadence/testsuite"
)

func TestHelloWorkflow(t *testing.T) {
    testSuite := &testsuite.WorkflowTestSuite{}
    env := testSuite.NewTestWorkflowEnvironment()
    
    // Mock activity
    env.OnActivity(GreetingActivity, mock.Anything, "World").Return("Hello, World!", nil)
    
    // Execute workflow
    env.ExecuteWorkflow(HelloWorkflow, "World")
    
    // Verify workflow completed
    require.True(t, env.IsWorkflowCompleted())
    require.NoError(t, env.GetWorkflowError())
    
    // Verify result
    var result string
    require.NoError(t, env.GetWorkflowResult(&result))
    require.Equal(t, "Hello, World!", result)
}

Sample Repository

Cadence Go Samples

Complete examples including:

Hello World workflows
Error handling and retries
Signal and query patterns
Child workflow orchestration
Timer and sleep operations
Saga pattern implementation

Best Practices

Workflow Determinism

Never use time.Now() or rand.Random() directly
Use workflow.Now() and workflow.NewRandom()
Don’t call external services from workflow code
Use activities for all non-deterministic operations

Activity Design

Keep activities idempotent when possible
Implement heartbeats for long-running activities
Use appropriate timeout values
Handle transient errors with retry policies

Worker Configuration

Start with default settings and tune based on metrics
Monitor queue depth and adjust poller counts
Use sticky execution for better performance
Implement graceful shutdown handlers

Error Handling

Define clear retry policies for activities
Use typed errors for better error classification
Implement compensation logic for saga patterns
Log context information for debugging

Next Steps

Core Concepts

Understand workflows, activities, and task lists

Java Client

Explore the Java SDK for JVM applications

CLI Reference

Manage workflows with the Cadence CLI

Web UI

Monitor workflows visually

Get Started

Core Concepts

Architecture

Deployment

Operations

Client SDKs

Introduction

GitHub Repository

Installation

Prerequisites

Add Dependency

Import Packages

Quick Start

1. Define a Workflow

2. Define an Activity

3. Start a Worker

4. Execute a Workflow

Advanced Patterns

Child Workflows

Signals and Queries

Error Handling and Retries

Local Activities

Worker Configuration

Tuning Worker Performance

Worker Lifecycle Management

Testing

Unit Testing Workflows

Sample Repository

Cadence Go Samples

Best Practices

Next Steps

Core Concepts

Java Client

CLI Reference

Web UI

Build docs developers (and LLMs) love

Get Started

Core Concepts

Architecture

Deployment

Operations

Client SDKs

​Introduction

GitHub Repository

​Installation

​Prerequisites

​Add Dependency

​Import Packages

​Quick Start

​1. Define a Workflow

​2. Define an Activity

​3. Start a Worker

​4. Execute a Workflow

​Advanced Patterns

​Child Workflows

​Signals and Queries

​Error Handling and Retries

​Local Activities

​Worker Configuration

​Tuning Worker Performance

​Worker Lifecycle Management

​Testing

​Unit Testing Workflows

​Sample Repository

Cadence Go Samples

​Best Practices

​Next Steps

Core Concepts

Java Client

CLI Reference

Web UI

Build docs developers (and LLMs) love

Introduction

Installation

Prerequisites

Add Dependency

Import Packages

Quick Start

1. Define a Workflow

2. Define an Activity

3. Start a Worker

4. Execute a Workflow

Advanced Patterns

Child Workflows

Signals and Queries

Error Handling and Retries

Local Activities

Worker Configuration

Tuning Worker Performance

Worker Lifecycle Management

Testing

Unit Testing Workflows

Sample Repository

Best Practices

Next Steps