In this tutorial, we’ll create a Next.js app that calls a long-running background job using QStash.

​
Prerequisites

  • Create an Upstash account and get your QStash token
  • Node.js installed
1

Create Next.js app and install QStash

npx create-next-app@latest --ts --eslint --tailwind --src-dir --app --import-alias='@/*' qstash-bg-job 

cd qstash-bg-job

npm install @upstash/qstash

npm run dev
2

Create UI

After removing the default content in src/app/page.tsx, let’s create a simple UI to trigger the background job using a button.

src/app/page.tsx
"use client"

export default function Home() {
  return (
    <main className="flex h-lvh items-center justify-center">
      <button onClick={handleClick} className="btn btn-primary w-1/2 h-56 bg-green-500 text-xl sm:text-3xl rounded-lg hover:bg-green-600">
        Start Background Job
      </button>
    </main>
  );
}
3

Start Background Job

We can use QStash to start a background job by calling the publishJSON method. In this example, we’re using Next.js server actions, but you can also use route handlers.

Since we don’t have our public API endpoint yet, we can use Request Catcher to test the background job. This will eventually be replaced with our own API endpoint.

src/app/actions.ts
"use server"
import { Client } from "@upstash/qstash";

const qstashClient = new Client({
  // Add your token to a .env file
  token: process.env.QSTASH_TOKEN!,
});

export async function startBackgroundJob() {
  await qstashClient.publishJSON({
    "url": "https://firstqstashmessage.requestcatcher.com/test",
    body: {
      "hello": "world"
    }
  });
}

Now let’s invoke the startBackgroundJob function when the button is clicked.

src/app/page.tsx
"use client"
import { startBackgroundJob } from "@/app/actions";

export default function Home() {
  async function handleClick() {
    await startBackgroundJob();
  }

  return (
    <main className="flex h-lvh items-center justify-center">
      <button onClick={handleClick} className="btn btn-primary w-1/2 h-56 bg-green-500 text-xl sm:text-3xl rounded-lg hover:bg-green-600">
        Start Background Job
      </button>
    </main>
  );
}

To test the background job, click the button and check the Request Catcher for the incoming request.

4

Create your own endpoint

Now that we know QStash is working, let’s create our own endpoint to handle a background job. This is the endpoint that will be invoked by QStash.

This job will be responsible for sending 10 requests, each with a 500ms delay. Since we’re deploying to Vercel, we have to be cautious of the time limit for serverless functions.

src/app/api/long-task/route.ts
export async function POST(request: Request) {
  const data = await request.json()

  for (let i = 0; i < 10; i++) {
    await fetch('https://firstqstashmessage.requestcatcher.com/test', {
      method: 'POST',
      body: JSON.stringify(data),
      headers: { 'Content-Type': 'application/json' }
    })
    await new Promise(resolve => setTimeout(resolve, 500))
  }


  return Response.json({ success: true })
}

Now let’s update our startBackgroundJob function to use our new endpoint.

There’s 1 problem: our endpoint is not public. We need to make it public so that QStash can call it. We have 2 options:

  1. Deploy our application to a platform like Vercel and use the public URL.
  2. Create a local tunnel to test the endpoint locally.

For the purpose, of this tutorial, I’ll deploy the application to Vercel, but feel free to use a local tunnel if you prefer.

Now that we have a public URL, we can update the URL.

src/app/actions.ts
"use server"
import { Client } from "@upstash/qstash";

const qstashClient = new Client({
  token: process.env.QSTASH_TOKEN!,
});

export async function startBackgroundJob() {
  await qstashClient.publishJSON({
    // Replace with your public URL
    "url": "https://qstash-bg-job.vercel.app/api/long-task",
    body: {
      "hello": "world"
    }
  })
}

And voila! You’ve created a Next.js app that calls a long-running background job using QStash.

5

Error catching and security

QStash is a great way to handle background jobs, but it’s important to remember that it’s a public API. This means that anyone can call your endpoint. Make sure to add security measures to your endpoint to ensure that QStash is the sender of the request.

Luckily, our SDK provides a way to verify the sender of the request. Make sure to get your signing keys from the QStash console and add them to your environment variables. The verifySignatureAppRouter will try to load QSTASH_CURRENT_SIGNING_KEY and QSTASH_NEXT_SIGNING_KEY from the environment. If one of them is missing, an error is thrown.

src/app/api/long-task/route.ts
import { verifySignatureAppRouter } from "@upstash/qstash/dist/nextjs";

async function handler(request: Request) {
  const data = await request.json();

  for (let i = 0; i < 10; i++) {
    await fetch('https://firstqstashmessage.requestcatcher.com/test', {
      method: 'POST',
      body: JSON.stringify(data),
      headers: { 'Content-Type': 'application/json' }
    });
    await new Promise(resolve => setTimeout(resolve, 500));
  }


  return Response.json({ success: true });
}

export const POST = verifySignatureAppRouter(handler);

Let’s also add error catching to our action and a loading state to our UI.

​
Result

We have now created a Next.js app that calls a long-running background job using QStash! Here’s the app in action:

We can also view the logs on Vercel and QStash

And the code for the 3 files we created:

Now, go ahead and try it out for yourself! Try using some of the other features of QStash, like schedules, callbacks, and topics.

Was this page helpful?

ComparePython on Vercel