workflow/docs/getting-started/hono.mdx

Workflow SDK - Build durable, resilient, and observable workflows

---
title: Hono
description: This guide will walk through setting up your first workflow in a Hono app. Along the way, you'll learn more about the concepts that are fundamental to using the Workflow SDK in your own projects.
type: guide
summary: Set up Workflow SDK in a Hono app.
prerequisites:
  - /docs/getting-started
related:
  - /docs/foundations/workflows-and-steps
---

<CopyPrompt
  text="In this Hono app, run `npm i workflow nitro rollup`. Create `nitro.config.ts` with `modules: [&quot;workflow/nitro&quot;]` and `routes: { &quot;/**&quot;: &quot;./src/index.ts&quot; }`. Add package scripts `dev: &quot;nitro dev&quot;` and `build: &quot;nitro build&quot;`. Add the TypeScript plugin `{ &quot;name&quot;: &quot;workflow&quot; }` to `tsconfig.json` if TypeScript is used. Create `workflows/user-signup.ts` with `handleUserSignup(email)`, `&quot;use workflow&quot;`, `sleep` from `workflow`, and `&quot;use step&quot;` helpers. Add `src/index.ts` with a Hono app, POST `/api/signup`, `start(handleUserSignup, [email])` from `workflow/api`, and JSON response. Run `npm run dev`, call `curl -X POST --json '{&quot;email&quot;:&quot;hello@example.com&quot;}' http://localhost:3000/api/signup`, and inspect with `npx workflow web` or `npx workflow inspect runs`."
/>

<Steps>

<Step>
## Create your Hono project

Start by creating a new Hono project. This command will create a new directory named `my-workflow-app` and set up a Hono project inside it.

```bash
npm create hono@latest my-workflow-app -- --template=nodejs
```

Enter the newly created directory:

```bash
cd my-workflow-app
```

### Install `workflow`, `nitro`, and `rollup`

```package-install
npm i workflow nitro rollup
```

<Callout>
By default, Hono doesn't include a build system. Nitro adds one which enables compiling workflows, runs, and deploys for development and production. Learn more about Nitro [here](https://v3.nitro.build).
</Callout>

### Configure Nitro

Create a new file `nitro.config.ts` for your Nitro configuration with module `workflow/nitro`. This enables usage of the `"use workflow"` and `"use step"` directives.

```typescript title="nitro.config.ts" lineNumbers
import { defineConfig } from "nitro";

export default defineConfig({
  modules: ["workflow/nitro"],
  routes: {
    "/**": "./src/index.ts"
  }
});
```

<Details>
<Summary>Setup IntelliSense for TypeScript (Optional)</Summary>

To enable helpful hints in your IDE, setup the workflow plugin in `tsconfig.json`:

```json title="tsconfig.json" lineNumbers
{
  "compilerOptions": {
    // ... rest of your TypeScript config
    "plugins": [
      {
        "name": "workflow" // [!code highlight]
      }
    ]
  }
}
```

</Details>

### Update `package.json`

To use the Nitro builder, update your `package.json` to include the following scripts:

```json title="package.json" lineNumbers
{
  // ...
  "scripts": {
    "dev": "nitro dev",
    "build": "nitro build"
  },
  // ...
}
```

</Step>

<Step>

## Create your first workflow

Create a new file for our first workflow:

```typescript title="workflows/user-signup.ts" lineNumbers
import { sleep } from "workflow";

export async function handleUserSignup(email: string) {
  "use workflow"; // [!code highlight]

  const user = await createUser(email);
  await sendWelcomeEmail(user);

  await sleep("5s"); // Pause for 5s - doesn't consume any resources
  await sendOnboardingEmail(user);

  console.log("Workflow is complete! Run 'npx workflow web' to inspect your run")

  return { userId: user.id, status: "onboarded" };
}
```

We'll fill in those functions next. The current code does the following:

- We define a **workflow** function with the directive `"use workflow"`. Think of the workflow function as the _orchestrator_ of individual **steps**.
- The Workflow SDK's `sleep` function allows us to suspend execution of the workflow without using up any resources. A sleep can be a few seconds, hours, days, or even months long.

## Create your workflow steps

Define the missing functions.

```typescript title="workflows/user-signup.ts" lineNumbers
import { FatalError } from "workflow";

// Our workflow function defined earlier

async function createUser(email: string) {
  "use step"; // [!code highlight]

  console.log(`Creating user with email: ${email}`);

  // Full Node.js access - database calls, APIs, etc.
  return { id: crypto.randomUUID(), email };
}

async function sendWelcomeEmail(user: { id: string; email: string }) {
  "use step"; // [!code highlight]

  console.log(`Sending welcome email to user: ${user.id}`);

  if (Math.random() < 0.3) {
    // By default, steps will be retried for unhandled errors
    throw new Error("Retryable!");
  }
}

async function sendOnboardingEmail(user: { id: string; email: string }) {
  "use step"; // [!code highlight]

  if (!user.email.includes("@")) {
    // To skip retrying, throw a FatalError instead
    throw new FatalError("Invalid Email");
  }

  console.log(`Sending onboarding email to user: ${user.id}`);
}
```

Taking a look at this code:

- Business logic lives inside **steps**. When a workflow invokes a step, the workflow suspends while the step runs with full Node.js access. The combined handler may execute it inline; queued retries and continuations return through the same flow route.
- If a step throws an error, like in `sendWelcomeEmail`, the step will automatically be retried until it succeeds (or hits the step's max retry count).
- Steps can throw a `FatalError` if an error is intentional and should not be retried.

<Callout>
  We'll dive deeper into workflows, steps, and other ways to suspend or handle
  events in [Foundations](/docs/foundations).
</Callout>

</Step>

<Step>

## Create your route handler

To invoke your new workflow, we'll create a new API route handler at `src/index.ts` with the following code:

```typescript title="src/index.ts"
import { Hono } from "hono";
import { start } from "workflow/api";
import { handleUserSignup } from "../workflows/user-signup.js";

const app = new Hono();

app.post("/api/signup", async (c) => {
  const { email } = await c.req.json();
  await start(handleUserSignup, [email]);
  return c.json({ message: "User signup workflow started" });
});

export default app;
```

This route handler creates a `POST` request endpoint at `/api/signup` that will trigger your workflow.

</Step>

<Step>

## Run in development

To start your development server, run the following command in your terminal in the Hono root directory:

```bash
npm run dev
```

Once your development server is running, you can trigger your workflow by running this command in the terminal:

```bash
curl -X POST --json '{"email":"hello@example.com"}' http://localhost:3000/api/signup
```

Check the Hono development server logs to see your workflow execute as well as the steps that are being processed.

Additionally, you can use the [Workflow SDK CLI or Web UI](/docs/observability) to inspect your workflow runs and steps in detail.

```bash
# Open the observability Web UI
npx workflow web
# or if you prefer a terminal interface, use the CLI inspect command
npx workflow inspect runs
```

![Workflow SDK Web UI](/o11y-ui.png)

</Step>

</Steps>

## Deploying to production

Workflow SDK apps currently work best when deployed to [Vercel](https://vercel.com/home) and need no special configuration.

<FluidComputeCallout />

Check the [Deploying](/docs/deploying) section to learn how your workflows can be deployed elsewhere.

## Troubleshooting

### `start()` says it received an invalid workflow function

If you see this error:

```text
'start' received an invalid workflow function. Ensure the Workflow SDK is configured correctly and the function includes a 'use workflow' directive.
```

Check both of these first:

1. The workflow function includes `"use workflow"`.
2. Your Nitro config includes the `workflow/nitro` module.

See [start-invalid-workflow-function](/docs/errors/start-invalid-workflow-function) for full examples and fixes.

## Next steps

- Learn more about the [Foundations](/docs/foundations).
- Check [Errors](/docs/errors) if you encounter issues.
- Explore the [API Reference](/docs/api-reference).