> ## Documentation Index
> Fetch the complete documentation index at: https://upstash-vector.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Use Serverless Kafka to Produce Events in Cloudflare Workers

In this tutorial, we will produce events to Upstash Kafka from a Cloudflare
Workers function.

### Create Kafka

First, create an Upstash Kafka cluster and topic following
[those steps.](https://docs.upstash.com/kafka) You will need the endpoint,
username and password in the following steps.

<Frame>
  <img src="https://mintlify.s3-us-west-1.amazonaws.com/upstash-vector/img/kafka/howto/awslambda/cluster_detail.png" width="100%" />
</Frame>

### Create Project

We will use
[Wrangler](https://developers.cloudflare.com/workers/get-started/guide) to
create the application. After installing and configuring wrangler, create a
folder for your project inside the folder run: `wrangler init`

It will create `wrangler.toml`. Paste your account id to the toml which is
logged by wrangler.

Copy and paste the Upstash Kafka URL, topic name, username and password to the
toml.

```toml
name = "produce-in-cloudflare-workers"
type = 'webpack'
account_id = 'REPLACE_HERE'
route = ''
zone_id = ''
usage_model = ''
workers_dev = true
target_type = "webpack"

[vars]
UPSTASH_KAFKA_REST_URL = "REPLACE_HERE"
UPSTASH_KAFKA_REST_USERNAME = "REPLACE_HERE"
UPSTASH_KAFKA_REST_PASSWORD = "REPLACE_HERE"
```

### Implement the Function

Init a node project and install @upstash/kafka:

```
npm init
npm install @upstash/kafka
```

Add the index.js as below:

```javascript
import { Kafka } from "@upstash/kafka";

addEventListener("fetch", (event) => {
  event.respondWith(handleRequest(event.request));
});

async function handleRequest(request) {
  console.log("START", request);

  const kafka = new Kafka({
    url: UPSTASH_KAFKA_REST_URL,
    username: UPSTASH_KAFKA_REST_USERNAME,
    password: UPSTASH_KAFKA_REST_PASSWORD,
  });

  const { pathname } = new URL(request.url);
  if (pathname.startsWith("/favicon")) {
    return fetch(request);
  }
  const p = kafka.producer();
  const message = { hello: "world" }; // Objects will get serialized using `JSON.stringify`
  const response = await p.produce("mytopic", message);

  return new Response(JSON.stringify(response));
}
```

The above code simply sends the message to Kafka. If your message is more
complicated then you can send it in the request body as explained
[here](./producewithrest).

### Run and Deploy the Function

Run the function locally: `wrangler dev`

Deploy your function to Cloudflare by running:

```
wrangler publish
```

This command will output your URL. The output of the URL should be something
like this:

```json
{
  "topic": "newtopic",
  "partition": 0,
  "offset": 278,
  "timestamp": 1640728294879
}
```

### Test the Function

Now let’s validate that the messages are pushed to Kafka. We can consume the
Kafka topic using the REST API. You can copy the curl code to consume from the
Upstash Console.

```
produce-in-lambda git:(master) ✗ curl https://full-mantis-14289-us1-rest-kafka.upstash.io/consume/GROUP_NAME/GROUP_INSTANCE_NAME/mytopic -u REPLACE_USER_NAME:REPLACE_PASSWORD

[ {
  "topic" : "newtopic",
  "partition" : 0,
  "offset" : 282,
  "timestamp" : 1639610767445,
  "key" : "",
  "value" : "hello",
  "headers" : [ ]
} ]%
```

### upstash-kafka vs other Kafka Clients

Upstash also supports native Kafka clients (e.g. KafkaJS). But Cloudflare
Workers runtime does not allow TCP connections.
[upstash-kafka](https://github.com/upstash/upstash-kafka) is HTTP based. That's
why we use [upstash-kafka](https://github.com/upstash/upstash-kafka) in our
Cloudflare examples.