Temporal Go

Temporal Go SDK

Build durable, fault-tolerant distributed applications using the Temporal Go SDK (go.temporal.io/sdk). Temporal provides workflow orchestration with automatic retries, state persistence, and exactly-once execution semantics.

Core Principles

• Deterministic Workflows: Workflow code must be deterministic. Never use time.Now(), rand, map range, goroutines, or I/O directly in Workflows.
• Activities for Side Effects: All non-deterministic operations (HTTP calls, DB queries, file I/O) go in Activities.
• Struct Parameters: Use single struct parameters and return values for forward compatibility.
• Idempotent Activities: Activities may be retried; design them to be safely re-executable.
• Explicit Error Handling: Use Temporal's typed errors (ApplicationError, TimeoutError, CanceledError) for control flow.

Project Structure

.
├── cmd/
│   ├── worker/           # Worker process entry point
│   └── starter/          # Workflow starter (client) entry point
├── workflows/            # Workflow definitions
│   ├── order.go
│   └── order_test.go
├── activities/           # Activity definitions
│   ├── payment.go
│   └── payment_test.go
├── shared/               # Shared types (params, results, constants)
│   └── types.go
├── go.mod
└── go.sum

Imports

import (
    // Client - for connecting to Temporal and starting workflows
    "go.temporal.io/sdk/client"

    // Workflow - for writing workflow definitions
    "go.temporal.io/sdk/workflow"

    // Activity - for writing activity definitions
    "go.temporal.io/sdk/activity"

    // Worker - for creating and running workers
    "go.temporal.io/sdk/worker"

    // Temporal - for error types and retry policies
    "go.temporal.io/sdk/temporal"

    // Testing - for test environments
    "go.temporal.io/sdk/testsuite"

    // Logging
    "go.temporal.io/sdk/log"
)

Workflow Definitions

Basic Workflow

A Workflow Definition is an exportable function. The first parameter must be workflow.Context. Return error or (result, error). Use struct params for forward compatibility.

package workflows

import (
    "time"
    "go.temporal.io/sdk/workflow"
)

type OrderInput struct {
    OrderID    string
    CustomerID string
    Items      []string
    Amount     float64
}

type OrderResult struct {
    OrderID       string
    PaymentID     string
    TrackingCode  string
    CompletedAt   string
}

func ProcessOrder(ctx workflow.Context, input OrderInput) (*OrderResult, error) {
    logger := workflow.GetLogger(ctx)
    logger.Info("ProcessOrder started", "orderID", input.OrderID)

    // Set activity options (StartToCloseTimeout OR ScheduleToCloseTimeout required)
    ao := workflow.ActivityOptions{
        StartToCloseTimeout: 30 * time.Second,
        RetryPolicy: &temporal.RetryPolicy{
            InitialInterval:    time.Second,
            BackoffCoefficient: 2.0,
            MaximumInterval:    time.Minute,
            MaximumAttempts:    5,
        },
    }
    ctx = workflow.WithActivityOptions(ctx, ao)

    // Use nil struct pointer to call struct-method Activities
    var a *Activities

    var paymentResult PaymentResult
    err := workflow.ExecuteActivity(ctx, a.ChargePayment, input).Get(ctx, &paymentResult)
    if err != nil {
        return nil, err
    }

    var shippingResult ShippingResult
    err = workflow.ExecuteActivity(ctx, a.ShipOrder, input).Get(ctx, &shippingResult)
    if err != nil {
        return nil, err
    }

    return &OrderResult{
        OrderID:      input.OrderID,
        PaymentID:    paymentResult.PaymentID,
        TrackingCode: shippingResult.TrackingCode,
        CompletedAt:  workflow.Now(ctx).Format(time.RFC3339),
    }, nil
}

Determinism Rules

Workflow code MUST be deterministic. Use Temporal SDK replacements for non-deterministic Go constructs:

Logging (replay-safe)

Always use workflow.GetLogger(ctx) -- it suppresses duplicate logs during replay:

logger := workflow.GetLogger(ctx)
logger.Info("Processing started", "orderID", orderID)
logger.Error("Activity failed", "Error", err)

Side Effects

Capture non-deterministic values (random numbers, UUIDs) so they are recorded in history and replayed consistently:

encodedRandom := workflow.SideEffect(ctx, func(ctx workflow.Context) interface{} {
    return rand.Intn(100)
})
var randomValue int
encodedRandom.Get(&randomValue)

Selectors (replacing select)

Use workflow.Selector to wait on multiple Futures and Channels. The selector picks the first ready callback.

func SampleTimerWorkflow(ctx workflow.Context, timeout time.Duration) error {
    ao := workflow.ActivityOptions{StartToCloseTimeout: 10 * time.Second}
    ctx = workflow.WithActivityOptions(ctx, ao)

    childCtx, cancelHandler := workflow.WithCancel(ctx)
    selector := workflow.NewSelector(ctx)

    var processingDone bool

    // Add a Future (activity result)
    f := workflow.ExecuteActivity(ctx, OrderProcessingActivity)
    selector.AddFuture(f, func(f workflow.Future) {
        processingDone = true
        cancelHandler() // cancel the timer
    })

    // Add a timer Future
    timerFuture := workflow.NewTimer(childCtx, timeout)
    selector.AddFuture(timerFuture, func(f workflow.Future) {
        if !processingDone {
            _ = workflow.ExecuteActivity(ctx, SendNotificationActivity).Get(ctx, nil)
        }
    })

    // Wait for the first to complete
    selector.Select(ctx)

    // If timer fired first, still wait for processing to finish
    if !processingDone {
        selector.Select(ctx)
    }

    return nil
}

Timers

// Simple sleep
workflow.Sleep(ctx, 5*time.Minute)

// Cancellable timer via NewTimer
timerCtx, timerCancel := workflow.WithCancel(ctx)
timer := workflow.NewTimer(timerCtx, 30*time.Minute)

// Cancel the timer when no longer needed
timerCancel()

Goroutines (workflow.Go)

Never use native go -- use workflow.Go() for deterministic coroutines:

func SampleGoroutineWorkflow(ctx workflow.Context, parallelism int) ([]string, error) {
    ao := workflow.ActivityOptions{StartToCloseTimeout: 10 * time.Second}
    ctx = workflow.WithActivityOptions(ctx, ao)

    var results []string
    var err error

    for i := 0; i < parallelism; i++ {
        input := fmt.Sprint(i) // capture outside lambda
        workflow.Go(ctx, func(gCtx workflow.Context) {
            // IMPORTANT: use gCtx (the goroutine context), not ctx
            var result string
            err = workflow.ExecuteActivity(gCtx, ProcessItem, input).Get(gCtx, &result)
            if err != nil {
                return
            }
            results = append(results, result)
        })
    }

    // Wait for all goroutines to complete
    _ = workflow.Await(ctx, func() bool {
        return err != nil || len(results) == parallelism
    })
    return results, err
}

Await and AwaitWithTimeout

Block a Workflow until a condition becomes true, without polling:

// Block indefinitely until condition is met
err := workflow.Await(ctx, func() bool {
    return isApproved
})

// Block with a timeout
ok, err := workflow.AwaitWithTimeout(ctx, 30*time.Second, func() bool {
    return isApproved
})
if err != nil {
    return err // canceled
}
if !ok {
    return temporal.NewApplicationError("approval timed out", "timeout")
}

Child Workflows

Execute a Workflow from within another Workflow:

func ParentWorkflow(ctx workflow.Context) (string, error) {
    cwo := workflow.ChildWorkflowOptions{
        WorkflowID: "child-workflow-id",
        // Optional: TaskQueue, RetryPolicy, etc.
    }
    ctx = workflow.WithChildOptions(ctx, cwo)

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

func ChildWorkflow(ctx workflow.Context, input string) (string, error) {
    logger := workflow.GetLogger(ctx)
    logger.Info("Child workflow started", "input", input)
    return "processed: " + input, nil
}

Continue-As-New

For long-running Workflows, use Continue-As-New to keep Event History from growing too large. This closes the current Workflow Execution and starts a fresh one with the same Workflow ID:

func LongRunningWorkflow(ctx workflow.Context, state WorkflowState) error {
    // Check if Temporal suggests continuing as new
    if workflow.GetInfo(ctx).GetContinueAsNewSuggested() {
        return workflow.NewContinueAsNewError(ctx, LongRunningWorkflow, state)
    }

    // ... do work, update state ...

    // Explicitly continue as new after N iterations
    state.Iteration++
    if state.Iteration >= 1000 {
        return workflow.NewContinueAsNewError(ctx, LongRunningWorkflow, state)
    }

    return nil
}

When using Update or Signal handlers, wait for them to finish before continuing as new:

err := workflow.Await(ctx, func() bool {
    return workflow.AllHandlersFinished(ctx)
})
if err != nil {
    return err
}
return workflow.NewContinueAsNewError(ctx, MyWorkflow, updatedState)

Signals

Signals are asynchronous messages sent to a running Workflow to change its state.

Handle Signals in a Workflow

const ApproveSignal = "approve"

type ApproveInput struct {
    ApproverName string
}

func ApprovalWorkflow(ctx workflow.Context, orderID string) error {
    logger := workflow.GetLogger(ctx)

    // Get the signal channel
    signalChan := workflow.GetSignalChannel(ctx, ApproveSignal)

    // Block until signal is received
    var approval ApproveInput
    signalChan.Receive(ctx, &approval)
    logger.Info("Received approval", "approver", approval.ApproverName)

    // Continue workflow execution after signal...
    return nil
}

Listen for Signals in a Background Goroutine

func OrderWorkflow(ctx workflow.Context) error {
    var lastSignalData string

    // Listen for signals in a separate goroutine
    workflow.Go(ctx, func(gCtx workflow.Context) {
        signalChan := workflow.GetSignalChannel(gCtx, "my-signal")
        for {
            selector := workflow.NewSelector(gCtx)
            selector.AddReceive(signalChan, func(c workflow.ReceiveChannel, more bool) {
                c.Receive(gCtx, &lastSignalData)
            })
            selector.Select(gCtx)
        }
    })

    // Main workflow logic continues...
    // lastSignalData is updated whenever a signal arrives
    return nil
}

Drain Signals Before Continue-As-New

Always drain buffered signals before completing or continuing as new:

signalChan := workflow.GetSignalChannel(ctx, "my-signal")
for {
    var data string
    ok := signalChan.ReceiveAsync(&data)
    if !ok {
        break
    }
    // process data
}

Queries

Queries are synchronous, read-only operations that inspect Workflow state. Query handlers must NOT mutate state.

Set a Query Handler

func QueryableWorkflow(ctx workflow.Context) error {
    currentState := "initialized"

    // Register a query handler
    err := workflow.SetQueryHandler(ctx, "get-state", func() (string, error) {
        return currentState, nil
    })
    if err != nil {
        return err
    }

    // Query handlers with input parameters
    err = workflow.SetQueryHandler(ctx, "get-item", func(itemID string) (*Item, error) {
        item, ok := items[itemID]
        if !ok {
            return nil, fmt.Errorf("item %s not found", itemID)
        }
        return item, nil
    })
    if err != nil {
        return err
    }

    // Workflow logic that updates currentState...
    currentState = "processing"
    workflow.Sleep(ctx, time.Minute)
    currentState = "done"
    return nil
}

Updates

Updates are synchronous, trackable requests that can mutate Workflow state and return results. They support validators for rejecting invalid requests before they are written to history.

Set an Update Handler

const FetchAndAdd = "fetch_and_add"
const Done = "done"

func CounterWorkflow(ctx workflow.Context) (int, error) {
    counter := 0

    // Update handler with validator
    err := workflow.SetUpdateHandlerWithOptions(
        ctx,
        FetchAndAdd,
        func(ctx workflow.Context, addend int) (int, error) {
            previous := counter
            counter += addend
            return previous, nil
        },
        workflow.UpdateHandlerOptions{
            Validator: func(ctx workflow.Context, addend int) error {
                if addend < 0 {
                    return fmt.Errorf("addend must be non-negative (%d)", addend)
                }
                return nil
            },
        },
    )
    if err != nil {
        return 0, err
    }

    // Wait for a "done" signal to finish
    _ = workflow.GetSignalChannel(ctx, Done).Receive(ctx, nil)
    return counter, ctx.Err()
}

Update Handlers with Activities and Mutexes

For safe concurrent access, use workflow.Mutex:

type Manager struct {
    state    map[string]string
    nodeLock workflow.Mutex
}

func (m *Manager) AssignNode(ctx workflow.Context, input AssignInput) (AssignResult, error) {
    // Wait until ready
    err := workflow.Await(ctx, func() bool { return m.isStarted })
    if err != nil {
        return AssignResult{}, err
    }

    // Acquire mutex for safe concurrent access
    err = m.nodeLock.Lock(ctx)
    if err != nil {
        return AssignResult{}, err
    }
    defer m.nodeLock.Unlock()

    // Execute activity while holding lock
    actCtx := workflow.WithActivityOptions(ctx, workflow.ActivityOptions{
        ScheduleToCloseTimeout: 10 * time.Second,
    })
    err = workflow.ExecuteActivity(actCtx, DoAssignment, input).Get(actCtx, nil)
    if err != nil {
        return AssignResult{}, err
    }

    m.state[input.NodeID] = input.JobName
    return AssignResult{NodeID: input.NodeID}, nil
}

Activity Definitions

Basic Activity

Activities are normal Go functions. The first parameter should be context.Context. They can perform any operation (I/O, HTTP calls, DB queries).

package activities

import (
    "context"
    "go.temporal.io/sdk/activity"
)

// Simple function activity
func SendEmail(ctx context.Context, recipient, subject, body string) error {
    logger := activity.GetLogger(ctx)
    logger.Info("Sending email", "to", recipient)
    // ... actual email sending logic ...
    return nil
}

Struct-Based Activities (recommended for dependencies)

Use struct methods when Activities need shared dependencies (DB pools, HTTP clients, configs). This is the recommended pattern.

type Activities struct {
    DBPool    *pgxpool.Pool
    APIClient *http.Client
    Config    *AppConfig
}

type PaymentInput struct {
    OrderID  string
    Amount   float64
    Currency string
}

type PaymentResult struct {
    PaymentID string
    Status    string
}

func (a *Activities) ChargePayment(ctx context.Context, input PaymentInput) (*PaymentResult, error) {
    logger := activity.GetLogger(ctx)
    logger.Info("Charging payment", "orderID", input.OrderID, "amount", input.Amount)

    // Use shared dependencies
    result, err := a.APIClient.Post(/* ... */)
    if err != nil {
        return nil, err
    }

    return &PaymentResult{
        PaymentID: result.ID,
        Status:    "charged",
    }, nil
}

func (a *Activities) RefundPayment(ctx context.Context, input PaymentInput) error {
    // Compensation activity for saga pattern
    logger := activity.GetLogger(ctx)
    logger.Info("Refunding payment", "orderID", input.OrderID)
    // ... refund logic ...
    return nil
}

When calling struct-method activities from a Workflow, use a nil struct pointer:

// In workflow code:
var a *Activities  // nil pointer is fine -- used only for method resolution
err := workflow.ExecuteActivity(ctx, a.ChargePayment, input).Get(ctx, &result)

Activity Heartbeating

Long-running Activities should heartbeat to report progress. If the Activity fails and retries, it can resume from the last heartbeated progress.

func BatchProcessingActivity(ctx context.Context, startIdx, endIdx int) error {
    logger := activity.GetLogger(ctx)

    // Resume from last heartbeat on retry
    i := startIdx
    if activity.HasHeartbeatDetails(ctx) {
        var lastCompleted int
        if err := activity.GetHeartbeatDetails(ctx, &lastCompleted); err == nil {
            i = lastCompleted + 1
            logger.Info("Resuming from heartbeat", "index", i)
        }
    }

    for ; i <= endIdx; i++ {
        // Do work for item i...
        logger.Info("Processing item", "index", i)

        // Record progress -- also delivers cancellation signals
        activity.RecordHeartbeat(ctx, i)

        // Check for cancellation
        select {
        case <-ctx.Done():
            return ctx.Err()
        default:
        }
    }

    return nil
}

Set HeartbeatTimeout in the Workflow's ActivityOptions:

ao := workflow.ActivityOptions{
    StartToCloseTimeout: 24 * time.Hour,
    HeartbeatTimeout:    30 * time.Second,  // Must heartbeat at least every 30s
}

Activity Errors

import "go.temporal.io/sdk/temporal"

// Retryable error (default) -- will be retried per RetryPolicy
return temporal.NewApplicationError("temporary failure", "TempError", details)

// Non-retryable error -- will NOT be retried regardless of RetryPolicy
return temporal.NewNonRetryableApplicationError("bad input", "ValidationError", nil, details)

// Standard Go errors are converted to retryable ApplicationError automatically
return fmt.Errorf("something went wrong: %w", err)

Worker Setup

A Worker polls a Task Queue for Workflow Tasks and Activity Tasks.

package main

import (
    "log"

    "go.temporal.io/sdk/client"
    "go.temporal.io/sdk/worker"

    "myapp/activities"
    "myapp/workflows"
)

func main() {
    // Create a Temporal client (heavyweight -- create once per process)
    c, err := client.Dial(client.Options{
        HostPort:  "localhost:7233",       // default
        Namespace: "default",              // default
    })
    if err != nil {
        log.Fatalln("Unable to create client", err)
    }
    defer c.Close()

    // Create a Worker that listens on a specific Task Queue
    w := worker.New(c, "my-task-queue", worker.Options{
        // Optional: tune worker concurrency
        // MaxConcurrentActivityExecutionSize:     defaults to 1000
        // MaxConcurrentWorkflowTaskExecutionSize: defaults to 1000
    })

    // Register Workflow functions
    w.RegisterWorkflow(workflows.ProcessOrder)
    w.RegisterWorkflow(workflows.ApprovalWorkflow)

    // Register Activity struct (registers all exported methods)
    w.RegisterActivity(&activities.Activities{
        DBPool:    dbPool,
        APIClient: httpClient,
        Config:    config,
    })

    // Register standalone Activity functions
    w.RegisterActivity(activities.SendEmail)

    // Run the Worker (blocks until interrupt signal)
    err = w.Run(worker.InterruptCh())
    if err != nil {
        log.Fatalln("Unable to start worker", err)
    }
}

Custom Registration Names

// Custom Workflow type name
w.RegisterWorkflowWithOptions(workflows.ProcessOrder, workflow.RegisterOptions{
    Name: "OrderProcessing",
})

// Custom Activity type name
w.RegisterActivityWithOptions(activities.SendEmail, activity.RegisterOptions{
    Name: "EmailSender",
})

Client Usage

Starting a Workflow

package main

import (
    "context"
    "log"

    "go.temporal.io/sdk/client"
    "myapp/workflows"
)

func main() {
    c, err := client.Dial(client.Options{
        HostPort: client.DefaultHostPort,
    })
    if err != nil {
        log.Fatalln("Unable to create client", err)
    }
    defer c.Close()

    options := client.StartWorkflowOptions{
        ID:        "order-12345",          // Workflow ID (should be meaningful)
        TaskQueue: "my-task-queue",        // Must match Worker's task queue
        // Optional:
        // WorkflowExecutionTimeout: 24 * time.Hour,
        // RetryPolicy: &temporal.RetryPolicy{...},
    }

    input := workflows.OrderInput{
        OrderID:    "12345",
        CustomerID: "cust-789",
        Items:      []string{"item-a", "item-b"},
        Amount:     99.99,
    }

    we, err := c.ExecuteWorkflow(context.Background(), options, workflows.ProcessOrder, input)
    if err != nil {
        log.Fatalln("Unable to execute workflow", err)
    }

    log.Println("Started workflow", "WorkflowID", we.GetID(), "RunID", we.GetRunID())

    // Synchronously wait for the result
    var result workflows.OrderResult
    err = we.Get(context.Background(), &result)
    if err != nil {
        log.Fatalln("Workflow failed", err)
    }
    log.Printf("Workflow result: %+v\n", result)
}

Sending a Signal

// Signal from client
err = c.SignalWorkflow(
    context.Background(),
    "order-12345",        // Workflow ID
    "",                   // Run ID (empty = current run)
    "approve",            // Signal name
    ApproveInput{ApproverName: "Alice"},
)

// Signal-With-Start: signal if running, otherwise start + signal
_, err = c.SignalWithStartWorkflow(
    context.Background(),
    "order-12345",        // Workflow ID
    "approve",            // Signal name
    ApproveInput{ApproverName: "Alice"},  // Signal arg
    client.StartWorkflowOptions{
        TaskQueue: "my-task-queue",
    },
    workflows.ApprovalWorkflow,  // Workflow function
    orderInput,                  // Workflow arg
)

Signal from Another Workflow

// Inside a Workflow:
err := workflow.SignalExternalWorkflow(ctx, "target-workflow-id", "", "signal-name", signalData).Get(ctx, nil)

Querying a Workflow

result, err := c.QueryWorkflow(
    context.Background(),
    "order-12345",    // Workflow ID
    "",               // Run ID
    "get-state",      // Query type
    // Optional query args...
)
if err != nil {
    log.Fatalln("Query failed", err)
}
var state string
err = result.Get(&state)

Sending an Update

ctxWithTimeout, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()

updateHandle, err := c.UpdateWorkflow(ctxWithTimeout, client.UpdateWorkflowOptions{
    WorkflowID:   "counter-workflow-id",
    RunID:        "",                                       // empty = current run
    UpdateName:   "fetch_and_add",
    WaitForStage: client.WorkflowUpdateStageAccepted,       // or WorkflowUpdateStageCompleted
    Args:         []interface{}{5},
})
if err != nil {
    log.Fatalf("Update failed: %v", err)
}

var previousValue int
err = updateHandle.Get(ctxWithTimeout, &previousValue)

Cancelling a Workflow

err = c.CancelWorkflow(context.Background(), "order-12345", "")

Error Handling

Workflow Error Types

Handle different error types from Activity or Child Workflow failures:

err := workflow.ExecuteActivity(ctx, a.DoSomething, input).Get(ctx, nil)
if err != nil {
    var applicationErr *temporal.ApplicationError
    if errors.As(err, &applicationErr) {
        // Application-level error (from Activity code)
        switch applicationErr.Type() {
        case "ValidationError":
            // Handle validation error
        case "NotFound":
            // Handle not found
        default:
            return err
        }
    }

    var canceledErr *temporal.CanceledError
    if errors.As(err, &canceledErr) {
        // Workflow or Activity was canceled
        return err
    }

    var timeoutErr *temporal.TimeoutError
    if errors.As(err, &timeoutErr) {
        switch timeoutErr.TimeoutType() {
        case enumspb.TIMEOUT_TYPE_START_TO_CLOSE:
            // Activity took too long
        case enumspb.TIMEOUT_TYPE_HEARTBEAT:
            // Activity stopped heartbeating
        case enumspb.TIMEOUT_TYPE_SCHEDULE_TO_START:
            // No Worker picked up the task
        }
    }

    var panicErr *temporal.PanicError
    if errors.As(err, &panicErr) {
        // Activity panicked -- panicErr.Error() and panicErr.StackTrace() available
    }
}

Non-Retryable Errors

// In Activity code: return a non-retryable error to stop retries immediately
return temporal.NewNonRetryableApplicationError(
    "invalid input: email is required",
    "ValidationError",
    nil, // cause
)

// In Workflow code: check specific error types in NonRetryableErrorTypes
ao := workflow.ActivityOptions{
    RetryPolicy: &temporal.RetryPolicy{
        NonRetryableErrorTypes: []string{"ValidationError", "NotFound"},
    },
}

Retry Policies

Activity Retry Policy

Activities retry by default. Customize with temporal.RetryPolicy:

retryPolicy := &temporal.RetryPolicy{
    InitialInterval:        time.Second,       // First retry delay (default: 1s)
    BackoffCoefficient:     2.0,               // Multiplier for each retry (default: 2.0)
    MaximumInterval:        time.Minute,       // Cap on retry delay (default: 100x InitialInterval)
    MaximumAttempts:        5,                 // 0 = unlimited (default: 0)
    NonRetryableErrorTypes: []string{          // Error types that stop retries
        "ValidationError",
    },
}

ao := workflow.ActivityOptions{
    StartToCloseTimeout: 2 * time.Minute,
    HeartbeatTimeout:    10 * time.Second,
    RetryPolicy:         retryPolicy,
}
ctx = workflow.WithActivityOptions(ctx, ao)

Workflow Retry Policy

Workflows do NOT retry by default. Add a retry policy when starting the Workflow:

options := client.StartWorkflowOptions{
    ID:        "my-workflow",
    TaskQueue: "my-queue",
    RetryPolicy: &temporal.RetryPolicy{
        InitialInterval:    time.Second,
        BackoffCoefficient: 2.0,
        MaximumInterval:    100 * time.Second,
    },
}

Activity Options Reference

ao := workflow.ActivityOptions{
    // REQUIRED: at least one of these two must be set
    StartToCloseTimeout:    30 * time.Second,     // Max time for a single attempt
    ScheduleToCloseTimeout: 5 * time.Minute,      // Max total time including retries

    // OPTIONAL
    ScheduleToStartTimeout: time.Minute,           // Max time waiting for a Worker
    HeartbeatTimeout:       10 * time.Second,       // Must heartbeat within this interval
    TaskQueueName:          "special-queue",        // Override parent's task queue
    WaitForCancellation:    true,                   // Wait for Activity to handle cancellation
    RetryPolicy:            &temporal.RetryPolicy{},
    ActivityID:             "custom-id",
}
ctx = workflow.WithActivityOptions(ctx, ao)

Testing

Workflow Unit Tests with Mocked Activities

package workflows_test

import (
    "testing"

    "github.com/stretchr/testify/mock"
    "github.com/stretchr/testify/require"
    "go.temporal.io/sdk/testsuite"
)

func Test_ProcessOrderWorkflow(t *testing.T) {
    testSuite := &testsuite.WorkflowTestSuite{}
    env := testSuite.NewTestWorkflowEnvironment()

    // Mock activities
    var a *Activities
    env.OnActivity(a.ChargePayment, mock.Anything, mock.Anything).Return(
        &PaymentResult{PaymentID: "pay-123", Status: "charged"}, nil,
    )
    env.OnActivity(a.ShipOrder, mock.Anything, mock.Anything).Return(
        &ShippingResult{TrackingCode: "TRACK-456"}, nil,
    )

    // Execute the workflow
    input := OrderInput{OrderID: "order-1", Amount: 99.99}
    env.ExecuteWorkflow(ProcessOrder, input)

    // Assert
    require.True(t, env.IsWorkflowCompleted())
    require.NoError(t, env.GetWorkflowError())

    var result OrderResult
    require.NoError(t, env.GetWorkflowResult(&result))
    require.Equal(t, "pay-123", result.PaymentID)
    require.Equal(t, "TRACK-456", result.TrackingCode)
}

Test Activity Failure

func Test_ProcessOrder_PaymentFails(t *testing.T) {
    testSuite := &testsuite.WorkflowTestSuite{}
    env := testSuite.NewTestWorkflowEnvironment()

    var a *Activities
    env.OnActivity(a.ChargePayment, mock.Anything, mock.Anything).Return(
        nil, temporal.NewApplicationError("payment declined", "PaymentError"),
    )

    env.ExecuteWorkflow(ProcessOrder, OrderInput{OrderID: "order-1"})

    require.True(t, env.IsWorkflowCompleted())
    err := env.GetWorkflowError()
    require.Error(t, err)

    var appErr *temporal.ApplicationError
    require.True(t, errors.As(err, &appErr))
    require.Equal(t, "PaymentError", appErr.Type())
}

Mock with Custom Implementation

func Test_ProcessOrder_ValidatesInput(t *testing.T) {
    testSuite := &testsuite.WorkflowTestSuite{}
    env := testSuite.NewTestWorkflowEnvironment()

    var a *Activities
    env.OnActivity(a.ChargePayment, mock.Anything, mock.Anything).Return(
        func(ctx context.Context, input PaymentInput) (*PaymentResult, error) {
            // Custom implementation that validates the input
            require.Equal(t, "order-1", input.OrderID)
            require.Equal(t, 99.99, input.Amount)
            return &PaymentResult{PaymentID: "pay-123"}, nil
        },
    )

    env.OnActivity(a.ShipOrder, mock.Anything, mock.Anything).Return(
        &ShippingResult{TrackingCode: "TRACK-456"}, nil,
    )

    env.ExecuteWorkflow(ProcessOrder, OrderInput{OrderID: "order-1", Amount: 99.99})
    require.True(t, env.IsWorkflowCompleted())
    require.NoError(t, env.GetWorkflowError())
}

Activity Unit Tests

func Test_ChargePayment(t *testing.T) {
    testSuite := &testsuite.WorkflowTestSuite{}
    env := testSuite.NewTestActivityEnvironment()

    a := &Activities{
        APIClient: mockHTTPClient,
        Config:    testConfig,
    }
    env.RegisterActivity(a)

    result, err := env.ExecuteActivity(a.ChargePayment, PaymentInput{
        OrderID: "order-1",
        Amount:  50.00,
    })

    require.NoError(t, err)
    var paymentResult PaymentResult
    require.NoError(t, result.Get(&paymentResult))
    require.Equal(t, "charged", paymentResult.Status)
}

Test with Signals

func Test_ApprovalWorkflow_WithSignal(t *testing.T) {
    testSuite := &testsuite.WorkflowTestSuite{}
    env := testSuite.NewTestWorkflowEnvironment()

    // Send signal after a delay
    env.RegisterDelayedCallback(func() {
        env.SignalWorkflow("approve", ApproveInput{ApproverName: "Alice"})
    }, time.Millisecond*10)

    env.ExecuteWorkflow(ApprovalWorkflow, "order-1")

    require.True(t, env.IsWorkflowCompleted())
    require.NoError(t, env.GetWorkflowError())
}

Test with Queries

func Test_QueryableWorkflow(t *testing.T) {
    testSuite := &testsuite.WorkflowTestSuite{}
    env := testSuite.NewTestWorkflowEnvironment()

    env.RegisterDelayedCallback(func() {
        result, err := env.QueryWorkflow("get-state")
        require.NoError(t, err)
        var state string
        require.NoError(t, result.Get(&state))
        require.Equal(t, "processing", state)
    }, time.Millisecond*10)

    env.ExecuteWorkflow(QueryableWorkflow)
}

Integration Tests with Dev Server

func Test_Integration_WithDevServer(t *testing.T) {
    server, err := testsuite.StartDevServer(context.Background(), testsuite.DevServerOptions{
        ClientOptions: &client.Options{HostPort: ""}, // random port
    })
    require.NoError(t, err)
    defer func() { _ = server.Stop() }()

    c := server.Client()
    taskQueue := "integration-test-queue"

    // Start worker in background
    w := worker.New(c, taskQueue, worker.Options{})
    w.RegisterWorkflow(ProcessOrder)
    w.RegisterActivity(&Activities{/* deps */})

    go func() { _ = w.Run(worker.InterruptCh()) }()
    defer w.Stop()

    // Execute workflow
    we, err := c.ExecuteWorkflow(context.Background(), client.StartWorkflowOptions{
        ID:        "test-order-1",
        TaskQueue: taskQueue,
    }, ProcessOrder, OrderInput{OrderID: "test-1", Amount: 50.00})
    require.NoError(t, err)

    var result OrderResult
    err = we.Get(context.Background(), &result)
    require.NoError(t, err)
    require.Equal(t, "test-1", result.OrderID)
}

Test Suite Pattern (testify suite)

type OrderWorkflowSuite struct {
    suite.Suite
    testsuite.WorkflowTestSuite
    env *testsuite.TestWorkflowEnvironment
}

func (s *OrderWorkflowSuite) SetupTest() {
    s.env = s.NewTestWorkflowEnvironment()
}

func (s *OrderWorkflowSuite) AfterTest(suiteName, testName string) {
    s.env.AssertExpectations(s.T())
}

func (s *OrderWorkflowSuite) Test_HappyPath() {
    var a *Activities
    s.env.OnActivity(a.ChargePayment, mock.Anything, mock.Anything).Return(
        &PaymentResult{PaymentID: "p1"}, nil,
    )
    s.env.OnActivity(a.ShipOrder, mock.Anything, mock.Anything).Return(
        &ShippingResult{TrackingCode: "t1"}, nil,
    )

    s.env.ExecuteWorkflow(ProcessOrder, OrderInput{OrderID: "1"})
    s.True(s.env.IsWorkflowCompleted())
    s.NoError(s.env.GetWorkflowError())
}

func TestOrderWorkflowSuite(t *testing.T) {
    suite.Run(t, new(OrderWorkflowSuite))
}

Key Patterns

Saga / Compensation Pattern

Use Go's defer to build compensation logic. If a later step fails, earlier steps are automatically compensated in reverse order.

func TransferMoney(ctx workflow.Context, details TransferDetails) (err error) {
    ao := workflow.ActivityOptions{
        StartToCloseTimeout: time.Minute,
        RetryPolicy: &temporal.RetryPolicy{
            InitialInterval:    time.Second,
            BackoffCoefficient: 2.0,
            MaximumInterval:    time.Minute,
            MaximumAttempts:    3,
        },
    }
    ctx = workflow.WithActivityOptions(ctx, ao)

    // Step 1: Withdraw
    err = workflow.ExecuteActivity(ctx, Withdraw, details).Get(ctx, nil)
    if err != nil {
        return err
    }

    // Compensate Step 1 if later steps fail
    defer func() {
        if err != nil {
            errCompensation := workflow.ExecuteActivity(ctx, WithdrawCompensation, details).Get(ctx, nil)
            err = multierr.Append(err, errCompensation)
        }
    }()

    // Step 2: Deposit
    err = workflow.ExecuteActivity(ctx, Deposit, details).Get(ctx, nil)
    if err != nil {
        return err  // triggers WithdrawCompensation via defer
    }

    // Compensate Step 2 if later steps fail
    defer func() {
        if err != nil {
            errCompensation := workflow.ExecuteActivity(ctx, DepositCompensation, details).Get(ctx, nil)
            err = multierr.Append(err, errCompensation)
        }
    }()

    // Step 3: Notify (if this fails, both Deposit and Withdraw are compensated)
    err = workflow.ExecuteActivity(ctx, SendNotification, details).Get(ctx, nil)
    if err != nil {
        return err  // triggers DepositCompensation then WithdrawCompensation
    }

    return nil
}

Cancellation with Cleanup

When a Workflow is canceled, use workflow.NewDisconnectedContext to run cleanup Activities:

func CancellableWorkflow(ctx workflow.Context) error {
    ao := workflow.ActivityOptions{
        StartToCloseTimeout: 30 * time.Minute,
        HeartbeatTimeout:    5 * time.Second,
        WaitForCancellation: true,  // Wait for Activity to acknowledge cancel
    }
    ctx = workflow.WithActivityOptions(ctx, ao)

    // Cleanup runs even after cancellation
    defer func() {
        if !errors.Is(ctx.Err(), workflow.ErrCanceled) {
            return
        }
        // Get a new context that is NOT canceled
        newCtx, _ := workflow.NewDisconnectedContext(ctx)
        err := workflow.ExecuteActivity(newCtx, CleanupActivity).Get(newCtx, nil)
        if err != nil {
            workflow.GetLogger(ctx).Error("Cleanup failed", "Error", err)
        }
    }()

    // Long-running activity that can be canceled
    var result string
    err := workflow.ExecuteActivity(ctx, LongRunningActivity).Get(ctx, &result)
    return err
}

Polling Pattern: Frequent (Activity with Heartbeat)

Poll inside a single long-running Activity using heartbeats:

// Activity: polls until success, heartbeating to stay alive
func PollForResult(ctx context.Context) (string, error) {
    for {
        result, err := callExternalService(ctx)
        if err == nil {
            return result, nil
        }

        activity.RecordHeartbeat(ctx)

        select {
        case <-ctx.Done():
            return "", ctx.Err()
        case <-time.After(5 * time.Second):
            // poll again
        }
    }
}

// Workflow: use long timeout + heartbeat
func PollingWorkflow(ctx workflow.Context) (string, error) {
    ao := workflow.ActivityOptions{
        StartToCloseTimeout: 24 * time.Hour,
        HeartbeatTimeout:    30 * time.Second,
    }
    ctx = workflow.WithActivityOptions(ctx, ao)

    var result string
    err := workflow.ExecuteActivity(ctx, PollForResult).Get(ctx, &result)
    return result, err
}

Polling Pattern: Infrequent (Activity Retries)

Use the retry policy itself as the polling mechanism:

func InfrequentPollingWorkflow(ctx workflow.Context) (string, error) {
    ao := workflow.ActivityOptions{
        StartToCloseTimeout: 2 * time.Second,  // Short: just check once
        RetryPolicy: &temporal.RetryPolicy{
            BackoffCoefficient: 1,              // Constant interval
            InitialInterval:    60 * time.Second, // Poll every 60s
            // MaximumAttempts: 0 means unlimited retries
        },
    }
    ctx = workflow.WithActivityOptions(ctx, ao)

    var result string
    err := workflow.ExecuteActivity(ctx, CheckService).Get(ctx, &result)
    return result, err
}

// Activity: check once and return error if not ready
func CheckService(ctx context.Context) (string, error) {
    result, err := callExternalService(ctx)
    if err != nil {
        return "", err  // Will be retried per RetryPolicy
    }
    return result, nil
}

Parallel Activities with Futures

Launch multiple Activities in parallel and collect results:

func ParallelWorkflow(ctx workflow.Context, items []string) ([]Result, error) {
    ao := workflow.ActivityOptions{StartToCloseTimeout: 10 * time.Second}
    ctx = workflow.WithActivityOptions(ctx, ao)

    // Launch all activities
    var futures []workflow.Future
    for _, item := range items {
        future := workflow.ExecuteActivity(ctx, ProcessItem, item)
        futures = append(futures, future)
    }

    // Collect results (in order)
    var results []Result
    for _, future := range futures {
        var result Result
        if err := future.Get(ctx, &result); err != nil {
            return nil, err
        }
        results = append(results, result)
    }
    return results, nil
}

Process Results as They Complete (Selector)

func ProcessAsCompleted(ctx workflow.Context, items []string) error {
    ao := workflow.ActivityOptions{StartToCloseTimeout: 10 * time.Second}
    ctx = workflow.WithActivityOptions(ctx, ao)

    selector := workflow.NewSelector(ctx)
    var processErr error

    for _, item := range items {
        future := workflow.ExecuteActivity(ctx, ProcessItem, item)
        selector.AddFuture(future, func(f workflow.Future) {
          

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