DBOS Transact: Lightweight Durable Workflows

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This package is in alpha -- the roadmap of missing features is listed below.

What is DBOS?

DBOS provides lightweight durable workflows on top of Postgres. Instead of managing your own workflow orchestrator or task queue system, you can use DBOS to add durable workflows and queues to your program in just a few lines of code.

When Should I Use DBOS?

You should consider using DBOS if your application needs to reliably handle failures. For example, you might be building a payments service that must reliably process transactions even if servers crash mid-operation, or a long-running data pipeline that needs to resume seamlessly from checkpoints rather than restart from the beginning when interrupted.

Handling failures is costly and complicated, requiring complex state management and recovery logic as well as heavyweight tools like external orchestration services. DBOS makes it simpler: annotate your code to checkpoint it in Postgres and automatically recover from any failure. DBOS also provides powerful Postgres-backed primitives that makes it easier to write and operate reliable code, including durable queues, notifications, scheduling, event processing, and programmatic workflow management.

Features

💾 Durable Workflows

DBOS workflows make your program durable by checkpointing its state in Postgres. If your program ever fails, when it restarts all your workflows will automatically resume from the last completed step.

You add durable workflows to your existing Golang program by registering ordinary functions as workflows or running them as steps:

var (
    wf = dbos.WithWorkflow(workflow)
)

func workflow(ctx context.Context, _ string) (string, error) {
    _, err := dbos.RunAsStep(ctx, step1, "")
    if err != nil {
        return "", err
    }
    return dbos.RunAsStep(ctx, step2, "")
}

func step1(ctx context.Context, _ string) (string, error) {
    fmt.Println("Executing step 1")
    return "Step 1 completed", nil
}

func step2(ctx context.Context, _ string) (string, error) {
    fmt.Println("Executing step 2")
    return "Step 2 completed - Workflow finished successfully", nil
}

func main() {
    err := dbos.Launch()
    if err != nil {
        panic(err)
    }
    defer dbos.Shutdown()

    wf(context.Background(), "hello DBOS")
}

Workflows are particularly useful for

• Orchestrating business processes so they seamlessly recover from any failure.
• Building observable and fault-tolerant data pipelines.
• Operating an AI agent, or any application that relies on unreliable or non-deterministic APIs.

📒 Durable Queues

DBOS queues help you durably run tasks in the background. When you enqueue a workflow, one of your processes will pick it up for execution. DBOS manages the execution of your tasks: it guarantees that tasks complete, and that their callers get their results without needing to resubmit them, even if your application is interrupted.

Queues also provide flow control, so you can limit the concurrency of your tasks on a per-queue or per-process basis. You can also set timeouts for tasks, rate limit how often queued tasks are executed, deduplicate tasks, or prioritize tasks.

You can add queues to your workflows in just a couple lines of code. They don't require a separate queueing service or message broker—just Postgres.

var (
    queue  = dbos.NewWorkflowQueue("example-queue")
    taskWf = dbos.WithWorkflow(task)
)

func task(ctx context.Context, i int) (int, error) {
    time.Sleep(5 * time.Second)
    fmt.Printf("Task %d completed\n", i)
    return i, nil
}

func main() {
    err := dbos.Launch()
    if err != nil {
        panic(err)
    }
    defer dbos.Shutdown()

    fmt.Println("Enqueuing workflows")
    handles := make([]dbos.WorkflowHandle[int], 10)
    for i := range 10 {
        handle, err := taskWf(context.Background(), i, dbos.WithQueue(queue.Name))
        if err != nil {
            panic(fmt.Sprintf("failed to enqueue step %d: %v", i, err))
        }
        handles[i] = handle
    }
    results := make([]int, 10)
    for i, handle := range handles {
        result, err := handle.GetResult(context.Background())
        if err != nil {
            panic(fmt.Sprintf("failed to get result for step %d: %v", i, err))
        }
        results[i] = result
    }
    fmt.Printf("Successfully completed %d steps\n", len(results))
}

DBOS workflows

A workflow can be any function with the following signature:

type WorkflowFunc[P any, R any] func(ctx context.Context, input P) (R, error)

P and R must be concrete types (not any).

Workflows must be registered with DBOS using the WithWorkflow method before DBOS is launched.

Workflows can run steps, which can be any function with the following signature:

type StepFunc[P any, R any] func(ctx context.Context, input P) (R, error)

To run a step within a workflow, use RunAsStep. Importantly, you must pass to RunAsStep the context received in the workflow function.

The input and output of workflows and steps are memoized in your Postgres database for workflow recovery. Under the hood, DBOS uses the encoding/gob package for serialization (this means that only exported fields will be memoized and types without exported fields will generate an error.)

Roadmap:

• logging for DBOS internals -- consider accepting a user provided logger
• OTel trace generation and export
• OTel logs -- consider leveraging the user provided logger
• config?
• go doc
• workflows send and recv
• workflows set and get event
• workflow cancellation maps
• queue dedup
• queue priority
• workflow timeouts
• DBOS Client
• datasources & transactions

Getting started

Install the DBOS Transact package in your program:

github.com/dbos-inc/dbos-transact-go

You can store and export a Postgres connection string in the DBOS_SYSTEM_DATABASE_URL environment variable for DBOS to manage your workflows state. By default, DBOS will use postgres://postgres:${PGPASSWORD}@localhost:5432/dbos?sslmode=disable.