mtsbatalha/temporal-golang-pro

Temporal Go SDK (temporal-golang-pro)

Overview

Expert-level guide for building resilient, scalable, and deterministic distributed systems using the Temporal Go SDK. This skill transforms vague orchestration requirements into production-grade Go implementations, focusing on durable execution, strict determinism, and enterprise-scale worker configuration.

When to Use This Skill

• Designing Distributed Systems: When building microservices that require durable state and reliable orchestration.
• Implementing Complex Workflows: Using the Go SDK to handle long-running processes (days/months) or complex Saga patterns.
• Optimizing Performance: When workers need fine-tuned concurrency, mTLS security, or custom interceptors.
• Ensuring Reliability: Implementing idempotent activities, graceful error handling, and sophisticated retry policies.
• Maintenance & Evolution: Versioning running workflows or performing zero-downtime worker updates.

Do not use this skill when

• Using Temporal with other SDKs (Python, Java, TypeScript) - refer to their specific -pro skills.
• The task is a simple request/response without durability or coordination needs.
• High-level design without implementation (use workflow-orchestration-patterns).

Step-by-Step Guide

1. Gather Context: Proactively ask for:
   • Target Temporal Cluster (Cloud vs. Self-hosted) and Namespace.
   • Task Queue names and expected throughput.
   • Security requirements (mTLS paths, authentication).
   • Failure modes and desired retry/timeout policies.
2. Verify Determinism: Before suggesting workflow code, verify against these 5 Rules:
   • No native Go concurrency (goroutines).
   • No native time (time.Now, time.Sleep).
   • No non-deterministic map iteration (must sort keys).
   • No direct external I/O or network calls.
   • No non-deterministic random numbers.
3. Implement Incrementally: Start with shared Protobuf/Data classes, then Activities, then Workflows, and finally Workers.
4. Leverage Resources: If the implementation requires advanced patterns (Sagas, Interceptors, Replay Testing), explicitly refer to the implementation playbook and testing strategies.

Capabilities

Go SDK Implementation

• Worker Management: Deep knowledge of worker.Options, including MaxConcurrentActivityTaskPollers, WorkerStopTimeout, and StickyScheduleToStartTimeout.
• Interceptors: Implementing Client, Worker, and Workflow interceptors for cross-cutting concerns (logging, tracing, auth).
• Custom Data Converters: Integrating Protobuf, encrypted payloads, or custom JSON marshaling.

Advanced Workflow Patterns

• Durable Concurrency: Using workflow.Go, workflow.Channel, and workflow.Selector instead of native primitives.
• Versioning: Implementing safe code evolution using workflow.GetVersion and workflow.GetReplaySafeLogger.
• Large-scale Processing: Pattern for ContinueAsNew to manage history size limits (defaults: 50MB or 50K events).
• Child Workflows: Managing lifecycle, cancellation, and parent-child signal propagation.

Testing & Observability

• Testsuite Mastery: Using WorkflowTestSuite for unit and functional testing with deterministic time control.
• Mocking: Sophisticated activity and child workflow mocking strategies.
• Replay Testing: Validating code changes against production event histories.
• Metrics: Configuring Prometheus/OpenTelemetry exporters for worker performance tracking.

Examples

Example 1: Versioned Workflow (Deterministic)

// Note: imports omitted. Requires 'go.temporal.io/sdk/workflow', 'go.temporal.io/sdk/temporal', and 'time'.
func SubscriptionWorkflow(ctx workflow.Context, userID string) error {
    // 1. Versioning for logic evolution (v1 = DefaultVersion)
    v := workflow.GetVersion(ctx, "billing_logic", workflow.DefaultVersion, 2)

    for i := 0; i < 12; i++ {
        ao := workflow.ActivityOptions{
            StartToCloseTimeout: 5 * time.Minute,
            RetryPolicy: &temporal.RetryPolicy{MaximumAttempts: 3},
        }
        ctx = workflow.WithActivityOptions(ctx, ao)

        // 2. Activity Execution (Always handle errors)
        err := workflow.ExecuteActivity(ctx, ChargePaymentActivity, userID).Get(ctx, nil)
        if err != nil {
            workflow.GetLogger(ctx).Error("Payment failed", "Error", err)
            return err
        }

        // 3. Durable Sleep (Time-skipping safe)
        sleepDuration := 30 * 24 * time.Hour
        if v >= 2 {
            sleepDuration = 28 * 24 * time.Hour
        }

        if err := workflow.Sleep(ctx, sleepDuration); err != nil {
            return err
        }
    }
    return nil
}

Example 2: Full mTLS Worker Setup

func RunSecureWorker() error {
    // 1. Load Client Certificate and Key
    cert, err := tls.LoadX509KeyPair("client.pem", "client.key")
    if err != nil {
        return fmt.Errorf("failed to load client keys: %w", err)
    }

    // 2. Load CA Certificate for Server verification (Proper mTLS)
    caPem, err := os.ReadFile("ca.pem")
    if err != nil {
        return fmt.Errorf("failed to read CA cert: %w", err)
    }
    certPool := x509.NewCertPool()
    if !certPool.AppendCertsFromPEM(caPem) {
        return fmt.Errorf("failed to parse CA cert")
    }

    // 3. Dial Cluster with full TLS config
    c, err := client.Dial(client.Options{
        HostPort:  "temporal.example.com:7233",
        Namespace: "production",
        ConnectionOptions: client.ConnectionOptions{
            TLS: &tls.Config{
                Certificates: []tls.Certificate{cert},
                RootCAs:      certPool,
            },
        },
    })
    if err != nil {
        return fmt.Errorf("failed to dial temporal: %w", err)
    }
    defer c.Close()

    w := worker.New(c, "payment-queue", worker.Options{})
    w.RegisterWorkflow(SubscriptionWorkflow)

    if err := w.Run(worker.InterruptCh()); err != nil {
        return fmt.Errorf("worker run failed: %w", err)
    }
    return nil
}

Example 3: Selector & Signal Integration

func ApprovalWorkflow(ctx workflow.Context) (string, error) {
    var approved bool
    signalCh := workflow.GetSignalChannel(ctx, "approval-signal")

    // Use Selector to wait for multiple async events
    s := workflow.NewSelector(ctx)
    s.AddReceive(signalCh, func(c workflow.ReceiveChannel, _ bool) {
        c.Receive(ctx, &approved)
    })

    // Add 72-hour timeout timer
    s.AddReceive(workflow.NewTimer(ctx, 72*time.Hour).GetChannel(), func(c workflow.ReceiveChannel, _ bool) {
        approved = false
    })

    s.Select(ctx)

    if !approved {
        return "rejected", nil
    }
    return "approved", nil
}

Best Practices

• ✅ Do: Always handle errors from ExecuteActivity and client.Dial.
• ✅ Do: Use workflow.Go and workflow.Channel for concurrency.
• ✅ Do: Sort map keys before iteration to maintain determinism.
• ✅ Do: Use activity.RecordHeartbeat for activities lasting > 1 minute.
• ✅ Do: Test logic compatibility using replayer.ReplayWorkflowHistoryFromJSON.
• ❌ Don't: Swallow errors with _ or log.Fatal in production workers.
• ❌ Don't: Perform direct Network/Disk I/O inside a Workflow function.
• ❌ Don't: Rely on native time.Now() or rand.Int().
• ❌ Don't: Apply this to simple cron jobs that don't require durability.

Troubleshooting

• Panic: Determinism Mismatch: Usually caused by logic changes without workflow.GetVersion or non-deterministic code (e.g., native maps).
• Error: History Size Exceeded: History limit reached (default 50K events). Ensure ContinueAsNew is implemented.
• Worker Hang: Check WorkerStopTimeout and ensure all activities handle context cancellation.

Limitations

• Does not cover Temporal Cloud UI navigation or TLS certificate provisioning workflows.
• Does not cover Temporal Java, Python, or TypeScript SDKs; refer to their dedicated -pro skills.
• Assumes Temporal Server v1.20+ and Go SDK v1.25+; older SDK versions may have different APIs.
• Does not cover experimental Temporal features (e.g., Nexus, Multi-cluster Replication).
• Does not address global namespace configuration or multi-region failover setup.
• Does not cover Temporal Worker versioning via the worker-versioning feature flag (experimental).

Resources

• Implementation Playbook - Deep dive into Go SDK patterns.
• Testing Strategies - Unit, Replay, and Integration testing for Go.
• Temporal Go SDK Reference
• Temporal Go Samples

Related Skills

• grpc-golang - Internal transport protocol and Protobuf design.
• golang-pro - General Go performance tuning and advanced syntax.
• workflow-orchestration-patterns - Language-agnostic orchestration strategy.