vihren

Vihren

Vihren is a Go toolkit for building typed Temporal workflows with less boilerplate. You write ordinary Go activities and workflows, mark them with //vihren:activity and //vihren:workflow, and run vihren-gen to generate Temporal registration, workflow-side activity proxies, and typed workflow clients.

The v0.1 release focuses on one concrete path:

• typed workflow and activity code generation;
• a small runnable codegenhello example;
• an embedded Temporal runtime for local demos and single-process development.

Install

Requires Go 1.26 or newer.

go get github.com/vihren-dev/vihren
go install github.com/vihren-dev/vihren/cmd/vihren-gen@latest

The Smallest Example

Write an activity and a workflow:

package codegenhello

import (
	"context"
	"fmt"
	"time"

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

//go:generate vihren-gen ./...

const DefaultTaskQueue = "vihren-codegenhello"

type GreetingActivities struct {
	Prefix string
}

type GreetingInput struct {
	Name string
}

type GreetingOutput struct {
	Message string
}

// ComposeGreeting builds a greeting.
//
//vihren:activity
func (activities *GreetingActivities) ComposeGreeting(ctx context.Context, in GreetingInput) (GreetingOutput, error) {
	_ = ctx
	return GreetingOutput{Message: fmt.Sprintf("%s, %s", activities.Prefix, in.Name)}, nil
}

// HelloWorkflow calls the activity through the generated type-safe proxy.
//
//vihren:workflow
func HelloWorkflow(ctx workflow.Context, in GreetingInput) (GreetingOutput, error) {
	ctx = workflow.WithActivityOptions(ctx, workflow.ActivityOptions{StartToCloseTimeout: time.Second})
	return Activity.ComposeGreeting(ctx, in)
}

Run generation:

go generate ./...

The generated file contains:

• Register, which registers the workflow and activity on a Temporal worker;
• Activity, a workflow-safe activity proxy with compile-time checked arguments and result types;
• NewClient, a typed workflow client for starting and awaiting workflows.

In this example the 53-line workflow.go you write generates 84 lines of registration, proxy, and client code you never hand-write or hand-maintain.

Run The Example

From this repository, run the self-contained example directly:

go run ./examples/codegenhello/cmd/codegenhello-embedded

It starts Temporal inside the process, starts a worker, runs the generated typed workflow client, and prints:

Hello, Ada

No Docker, daemon, or separate Temporal development server is required.

If you use just, the same command is available as:

just run-codegenhello-embedded

To verify generated code and tests from a checkout:

go generate ./examples/codegenhello
go test ./examples/codegenhello ./examples/codegenhello/cmd/codegenhello-embedded -timeout 60s

Embedded Temporal

platform/embeddedtemporal runs a Temporal server inside the current process. It is useful for examples, demos, and single-binary local development. It is not a production Temporal deployment.

server, err := embeddedtemporal.Start()
if err != nil {
	return err
}
defer server.Close()

See docs/embedded-temporal.md and examples/codegenhello.

License

Vihren is licensed under the Apache License, Version 2.0. See the NOTICE file for attribution.