Dbos Go

DBOS for Go

DBOS provides durable execution so you can write programs that are resilient to any failure. When interrupted, workflows automatically resume from their last completed step. Requires PostgreSQL as its system database.

Core Concepts

Workflows

• Must be deterministic - calling with identical inputs should invoke same steps in same order
• Accept dbos.DBOSContext plus one serializable input
• Return one serializable output and an error
• Cannot spawn goroutines or use select
• Cannot modify global state (read-only access allowed)

Steps

• Regular Go functions called via dbos.RunAsStep()
• Must accept context.Context and return serializable value + error
• Used for non-deterministic operations (API calls, random, time, file I/O)
• Automatically skipped on recovery if previously completed

Queues

• Manage concurrent workflow execution with controlled flow
• Support rate limiting, priority, and deduplication
• Created with dbos.NewWorkflowQueue()

Essential Patterns

Basic Application Structure

package main

import (
    "context"
    "fmt"
    "os"
    "time"

    "github.com/dbos-inc/dbos-transact-golang/dbos"
)

func main() {
    dbosContext, err := dbos.NewDBOSContext(context.Background(), dbos.Config{
        AppName:     "my-app",
        DatabaseURL: os.Getenv("DBOS_SYSTEM_DATABASE_URL"),
    })
    if err != nil {
        panic(fmt.Sprintf("Initializing DBOS failed: %v", err))
    }

    // Register workflows BEFORE Launch
    dbos.RegisterWorkflow(dbosContext, myWorkflow)

    err = dbos.Launch(dbosContext)
    if err != nil {
        panic(fmt.Sprintf("Launching DBOS failed: %v", err))
    }
    defer dbos.Shutdown(dbosContext, 5*time.Second)

    // Application logic (HTTP server, etc.)
}

Workflow with Steps

func myWorkflow(ctx dbos.DBOSContext, input string) (string, error) {
    result1, err := dbos.RunAsStep(ctx, func(stepCtx context.Context) (string, error) {
        return callExternalAPI(stepCtx, input)
    }, dbos.WithStepName("callAPI"))
    if err != nil {
        return "", err
    }

    result2, err := dbos.RunAsStep(ctx, func(stepCtx context.Context) (string, error) {
        return processData(stepCtx, result1)
    }, dbos.WithStepName("processData"))
    if err != nil {
        return "", err
    }

    return result2, nil
}

Step with Retry Configuration

func fetchWithRetry(ctx dbos.DBOSContext, url string) (string, error) {
    return dbos.RunAsStep(
        ctx,
        func(stepCtx context.Context) (string, error) {
            resp, err := http.Get(url)
            if err != nil {
                return "", err
            }
            defer resp.Body.Close()
            body, _ := io.ReadAll(resp.Body)
            return string(body), nil
        },
        dbos.WithStepName("fetchURL"),
        dbos.WithStepMaxRetries(10),
        dbos.WithMaxInterval(30*time.Second),
        dbos.WithBackoffFactor(2.0),
        dbos.WithBaseInterval(500*time.Millisecond),
    )
}

Queue-Based Processing

func main() {
    dbosContext := initDBOS()

    queue := dbos.NewWorkflowQueue(dbosContext, "task_queue",
        dbos.WithWorkerConcurrency(5))

    // Or with rate limiting
    rateLimitedQueue := dbos.NewWorkflowQueue(dbosContext, "api_queue",
        dbos.WithRateLimiter(&dbos.RateLimiter{
            Limit:  100,
            Period: 60.0, // 100 requests per minute
        }))

    dbos.RegisterWorkflow(dbosContext, taskWorkflow)
    dbos.Launch(dbosContext)
}

func enqueueTask(ctx dbos.DBOSContext, queue dbos.WorkflowQueue, taskID int) error {
    handle, err := dbos.RunWorkflow(ctx, taskWorkflow, taskID,
        dbos.WithQueue(queue.Name))
    if err != nil {
        return err
    }
    _, err = handle.GetResult()
    return err
}

Workflow Communication - Messages

const PaymentTopic = "payment_status"

func checkoutWorkflow(ctx dbos.DBOSContext, orderID string) (string, error) {
    // Wait up to 5 minutes for payment confirmation
    notification, err := dbos.Recv(ctx, PaymentTopic, 300)
    if err != nil {
        return "", fmt.Errorf("payment timeout: %w", err)
    }

    if notification.Status == "completed" {
        return "order_completed", nil
    }
    return "payment_failed", nil
}

func paymentWebhook(dbosContext dbos.DBOSContext, workflowID string, status string) error {
    return dbos.Send(dbosContext, workflowID, PaymentNotification{Status: status}, PaymentTopic)
}

Workflow Communication - Events

const PaymentURLKey = "payment_url"

func checkoutWorkflow(ctx dbos.DBOSContext, order Order) (string, error) {
    url := generatePaymentURL(order)
    err := dbos.SetEvent(ctx, PaymentURLKey, url)
    if err != nil {
        return "", err
    }
    // Continue processing...
}

func checkoutHandler(dbosContext dbos.DBOSContext, w http.ResponseWriter, r *http.Request) {
    handle, _ := dbos.RunWorkflow(dbosContext, checkoutWorkflow, order)
    url, err := dbos.GetEvent[string](dbosContext, handle.GetWorkflowID(), PaymentURLKey, 30*time.Second)
    if err != nil {
        http.Error(w, "Timeout", http.StatusGatewayTimeout)
        return
    }
    http.Redirect(w, r, url, http.StatusSeeOther)
}

Durable Sleep

func scheduledTaskWorkflow(ctx dbos.DBOSContext, delay time.Duration) (string, error) {
    _, err := dbos.Sleep(ctx, delay)
    if err != nil {
        return "", err
    }
    return dbos.RunAsStep(ctx, func(stepCtx context.Context) (string, error) {
        return executeTask(stepCtx)
    })
}

Scheduled Workflows (Cron)

func main() {
    dbosContext := initDBOS()

    // Run daily at 2:00 AM
    dbos.RegisterWorkflow(dbosContext, dailyBackup,
        dbos.WithSchedule("0 0 2 * * *"))

    // Run every 15 minutes
    dbos.RegisterWorkflow(dbosContext, healthCheck,
        dbos.WithSchedule("0 */15 * * * *"))

    dbos.Launch(dbosContext)
}

Idempotent Workflows

func handlePayment(dbosContext dbos.DBOSContext, payment Payment) error {
    // Same workflow ID = same execution (prevents duplicates)
    handle, err := dbos.RunWorkflow(dbosContext, processPayment, payment,
        dbos.WithWorkflowID(payment.ID))
    if err != nil {
        return err
    }
    _, err = handle.GetResult()
    return err
}

Priority Queues

queue := dbos.NewWorkflowQueue(dbosContext, "priority_queue",
    dbos.WithPriorityEnabled())

// Lower number = higher priority
dbos.RunWorkflow(ctx, urgentTask, data,
    dbos.WithQueue(queue.Name),
    dbos.WithPriority(1))  // High priority

Child Workflows

func parentWorkflow(ctx dbos.DBOSContext, items []Item) ([]Result, error) {
    var results []Result
    for _, item := range items {
        handle, err := dbos.RunWorkflow(ctx, processItemWorkflow, item)
        if err != nil {
            return nil, err
        }
        result, err := handle.GetResult()
        if err != nil {
            return nil, err
        }
        results = append(results, result)
    }
    return results, nil
}

HTTP Integration with Gin

func main() {
    dbosContext := initDBOS()
    dbos.RegisterWorkflow(dbosContext, orderWorkflow)
    dbos.Launch(dbosContext)
    defer dbos.Shutdown(dbosContext, 5*time.Second)

    r := gin.Default()
    r.POST("/orders", func(c *gin.Context) {
        var order Order
        if err := c.ShouldBindJSON(&order); err != nil {
            c.JSON(400, gin.H{"error": err.Error()})
            return
        }
        handle, err := dbos.RunWorkflow(dbosContext, orderWorkflow, order)
        if err != nil {
            c.JSON(500, gin.H{"error": err.Error()})
            return
        }
        c.JSON(202, gin.H{"workflow_id": handle.GetWorkflowID(), "status": "processing"})
    })
    r.Run(":8080")
}

Critical Rules

Determinism Requirements

1. No direct randomness - Wrap in steps
2. No direct time access - Use dbos.Sleep() or wrap time.Now() in steps
3. No direct I/O - All API calls, file access, DB queries must be steps
4. No goroutines - Use queues or child workflows for parallelism
5. No global state mutation - Read-only access to globals

Step Requirements

• Must accept context.Context as first parameter
• Must return (T, error) where T is serializable
• Use dbos.WithStepName() for clarity in logs/debugging

Workflow Requirements

• Must accept dbos.DBOSContext as first parameter
• Must accept exactly one serializable input parameter
• Must return exactly one serializable output and error
• Must be registered before dbos.Launch()