pubsub

A set of useful helper methods for writing functions to handle Cloudflare Pub/Sub messages. This includes:

- A isValidBrokerRequest helper for authenticating incoming on-publish webhooks
- A PubSubMessage type with the fields sent from the Broker to your Worker for use with TypeScript-based Workers and/or for type-aware editors.

Installation

Use npm to install:

``sh
npm install @cloudflare/pubsub
`

Example

The following example shows how to use isValidBrokerRequest in a Worker to validate incoming on-publish webhooks from a Pub/Sub broker.

You can use wrangler to bundle your code for deployment to Cloudflare Workers.

`ts
import { isValidBrokerRequest, PubSubMessage } from "@cloudflare/pubsub"

async function pubsub(
messages: Array,
env: any,
ctx: ExecutionContext
): Promise> {

// Messages may be batched at higher throughputs, so we should loop over
// the incoming messages and process them as needed.
let messagesToKeep: Array
for (let msg of messages) {
console.log(msg);
// Drop debug messages sent by our clients to reduce the load on our
// subscribers.
if (!msg.topic.startsWith("debug") {
messagesToKeep.push(msg)
}
}

return messagesToKeep;
}

const worker = {
async fetch(req: Request, env: any, ctx: ExecutionContext) {
// Critical: you must validate the incoming request is from your Broker
// In the future, Workers will be able to do this on your behalf for Workers
// in the same account as your Pub/Sub Broker.
if (await isValidBrokerRequest(req)) {
// Parse the PubSub message
let incomingMessages: Array = await req.json();

// Pass the messages to our pubsub handler, and capture the returned
// message.
let outgoingMessages = await pubsub(incomingMessages, env, ctx);

// Re-serialize the messages and return a HTTP 200.
// The Content-Type is optional, but must either by
// "application/octet-stream" or left empty.
return new Response(JSON.stringify(outgoingMessages), { status: 200 });
}

return new Response("not a valid Broker request", { status: 403 });
},
};

export default worker;
`

You can use wranger publish to publish this directly: the latest wrangler` supports TypeScript natively.

License

BSD 3-Clause licensed. Copyright Cloudflare, Inc. 2022.