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

Temporal Go SDK Reference

Overview

The Temporal Go SDK (go.temporal.io/sdk) provides a strongly-typed, idiomatic Go approach to building durable workflows. Workflows are regular exported Go functions. The Go SDK does not have an automatic sandbox -- determinism is the developer's responsibility, aided by the workflowcheck static analysis tool.

Quick Start

Add Dependency: In your Go module, add the Temporal SDK:

go get go.temporal.io/sdk

workflows/greeting.go - Workflow definition:

package workflows

import (
	"time"

	"go.temporal.io/sdk/workflow"
)

func GreetingWorkflow(ctx workflow.Context, name string) (string, error) {
	ao := workflow.ActivityOptions{
		StartToCloseTimeout: time.Minute,
	}
	ctx = workflow.WithActivityOptions(ctx, ao)

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

activities/greet.go - Activity definition:

package activities

import (
	"context"
	"fmt"
)

type Activities struct{}

func (a *Activities) Greet(ctx context.Context, name string) (string, error) {
	return fmt.Sprintf("Hello, %s!", name), nil
}

worker/main.go - Worker setup:

package main

import (
	"log"

	"yourmodule/activities"
	"yourmodule/workflows"

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

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

	w := worker.New(c, "my-task-queue", worker.Options{})

	w.RegisterWorkflow(workflows.GreetingWorkflow)
	w.RegisterActivity(&activities.Activities{})

	err = w.Run(worker.InterruptCh())
	if err != nil {
		log.Fatalln("Unable to start worker", err)
	}
}

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

Start the worker: Run go run worker/main.go in the background.

starter/main.go - Start a workflow execution:

package main

import (
	"context"
	"fmt"
	"log"

	"yourmodule/workflows"

	"github.com/google/uuid"
	"go.temporal.io/sdk/client"
)

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

	options := client.StartWorkflowOptions{
		ID:        uuid.NewString(),
		TaskQueue: "my-task-queue",
	}

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

	var result string
	err = we.Get(context.Background(), &result)
	if err != nil {
		log.Fatalln("Unable to get workflow result", err)
	}

	fmt.Println("Result:", result)
}

Run the workflow: Run go run starter/main.go. Should output: Result: Hello, my name!.

Key Concepts

Workflow Definition

• Exported function with workflow.Context as the first parameter
• Returns (ResultType, error) or just error
• Signature: func MyWorkflow(ctx workflow.Context, input MyInput) (MyOutput, error)
• Use workflow.SetQueryHandler(), workflow.SetUpdateHandler() for handlers
• Register with w.RegisterWorkflow(MyWorkflow)

Activity Definition

• Regular function or struct methods with context.Context as the first parameter
• Struct methods are preferred for dependency injection
• Signature: func (a *Activities) MyActivity(ctx context.Context, input string) (string, error)
• Register struct with w.RegisterActivity(&Activities{}) (registers all exported methods)

Worker Setup

• Create client with client.Dial(client.Options{})
• Create worker with worker.New(c, "task-queue", worker.Options{})
• Register workflows and activities
• Run with w.Run(worker.InterruptCh())

Determinism

Workflow code must be deterministic! The Go SDK has no sandbox -- determinism is enforced by convention and tooling.

Use Temporal replacements instead of native Go constructs:

• workflow.Go() instead of go (goroutines)
• workflow.Channel instead of chan
• workflow.Selector instead of select
• workflow.Sleep() instead of time.Sleep()
• workflow.Now() instead of time.Now()
• workflow.GetLogger() instead of log / fmt.Println for replay-safe logging

Use the workflowcheck static analysis tool to catch non-deterministic code:

go install go.temporal.io/sdk/contrib/tools/workflowcheck@latest
workflowcheck ./...

Read references/core/determinism.md and references/go/determinism.md to understand more.

File Organization Best Practice

Use separate packages for workflows, activities, and worker. Activities as struct methods enable dependency injection at the worker level.

myapp/
├── workflows/
│   └── greeting.go      # Only Workflow functions
├── activities/
│   └── greet.go          # Activity struct and methods
├── worker/
│   └── main.go           # Worker setup, imports both
└── starter/
    └── main.go           # Client code to start workflows

Activities as struct methods for dependency injection:

// activities/greet.go
type Activities struct {
    HTTPClient *http.Client
    DB         *sql.DB
}

func (a *Activities) FetchData(ctx context.Context, url string) (string, error) {
    // Use a.HTTPClient, a.DB, etc.
}

// worker/main.go - inject dependencies at worker startup
activities := &activities.Activities{
    HTTPClient: http.DefaultClient,
    DB:         db,
}
w.RegisterActivity(activities)

Common Pitfalls

1. Using native goroutines/channels/select - Use workflow.Go(), workflow.Channel, workflow.Selector
2. Using time.Sleep or time.Now - Use workflow.Sleep() and workflow.Now()
3. Iterating over maps with range - Map iteration order is non-deterministic; sort keys first
4. Forgetting to register workflows/activities - Worker will fail tasks for unregistered types
5. Registering activity functions instead of struct - Use w.RegisterActivity(&Activities{}) not w.RegisterActivity(a.MyMethod)
6. Forgetting to heartbeat - Long-running activities need activity.RecordHeartbeat(ctx, details)
7. Using fmt.Println in workflows - Use workflow.GetLogger(ctx) for replay-safe logging
8. Not setting Activity timeouts - StartToCloseTimeout or ScheduleToCloseTimeout is required in ActivityOptions

Writing Tests

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

Additional Resources

Reference Files

• references/go/patterns.md - Signals, queries, child workflows, saga pattern, etc.
• references/go/determinism.md - Determinism rules, workflowcheck tool, safe alternatives
• references/go/gotchas.md - Go-specific mistakes and anti-patterns
• references/go/error-handling.md - ApplicationError, retry policies, non-retryable errors
• references/go/observability.md - Logging, metrics, tracing, Search Attributes
• references/go/testing.md - TestWorkflowEnvironment, time-skipping, activity mocking
• references/go/advanced-features.md - Schedules, worker tuning, and more
• references/go/data-handling.md - Data converters, payload codecs, encryption
• references/go/versioning.md - Patching API (workflow.GetVersion), Worker Versioning
• references/python/determinism-protection.md - Information on workflowcheck tool to help statically check for determinism issues.