Deploy a Browser Rendering Worker

By following this guide, you will create a Worker that uses the Browser Rendering API to take screenshots from web pages. This is a common use case for browser automation.

​​ Prerequisites

1. Sign up for a Cloudflare account Open external link .
2. Install npm Open external link .
3. Install Node.js Open external link .

​​ 1. Create a Worker project

Cloudflare Workers provides a serverless execution environment that allows you to create new applications or augment existing ones without configuring or maintaining infrastructure. Your Worker application is a container to interact with a headless browser to do actions, such as taking screenshots.

Create a new Worker project named browser-worker by running:

$ npm create cloudflare@latest

$ yarn create cloudflare@latest

You can choose to use either JavaScript or TypeScript for this guide.

​​ 2. Install Puppeteer

In your browser-worker directory, install Cloudflare’s fork of Puppeteer:

$ npm install @cloudflare/puppeteer --save-dev

​​ 3. Create a KV namespace

Browser Rendering can be used with other developer products. You might need a relational database, an R2 bucket to archive your crawled pages and assets, a Durable Object to keep your browser instance alive and share it with multiple requests, or Queues to handle your jobs asynchronous.

For the purpose of this guide, you are going to use a KV store to cache your screenshots.

Create two namespaces, one for production, and one for development.

npx wrangler kv:namespace create BROWSER_KV_DEMO
npx wrangler kv:namespace create BROWSER_KV_DEMO --preview

Take note of the IDs for the next step.

​​ 4. Configure wrangler.toml

Configure your browser-worker project’s wrangler.toml file by adding a browser binding and a Node.js compatibility flag. Bindings allow your Workers to interact with resources on the Cloudflare developer platform. Your browser binding name is set by you, this guide uses the name MYBROWSER. Browser bindings allow for communication between a Worker and a headless browser which allows you to do actions such as taking a screenshot, generating a PDF and more.

Update your wrangler.toml configuration file with the Browser Rendering API binding and the KV namespaces you created:

wrangler.toml
name = "browser-worker"
main = "src/worker.js"
compatibility_date = "2023-03-14"
compatibility_flags = [ "nodejs_compat" ]

browser = { binding = "MYBROWSER" }
kv_namespaces = [
  { binding = "BROWSER_KV_DEMO", id = "22cf855786094a88a6906f8edac425cd", preview_id = "e1f8b68b68d24381b57071445f96e623" }
]

​​ 5. Code

import puppeteer from "@cloudflare/puppeteer";

export default {
	async fetch(request, env) {
		const { searchParams } = new URL(request.url);
		let url = searchParams.get("url");
		let img;
		if (url) {
			url = new URL(url).toString(); // normalize
			img = await env.BROWSER_KV_DEMO.get(url, { type: "arrayBuffer" });
			if (img === null) {
				const browser = await puppeteer.launch(env.MYBROWSER);
				const page = await browser.newPage();
				await page.goto(url);
				img = await page.screenshot();
				await env.BROWSER_KV_DEMO.put(url, img, {
					expirationTtl: 60 * 60 * 24,
				});
				await browser.close();
			}
			return new Response(img, {
				headers: {
					"content-type": "image/jpeg",
				},
			});
		} else {
			return new Response(
				"Please add an ?url=https://example.com/ parameter"
			);
		}
	},
};

import puppeteer from "@cloudflare/puppeteer";

interface Env {
	MYBROWSER: Fetcher;
	BROWSER_KV_DEMO: KVNamespace;
}

export default {
	async fetch(request: Request, env: Env): Promise<Response> {
		const { searchParams } = new URL(request.url);
		let url = searchParams.get("url");
		let img: Buffer;
		if (url) {
			url = new URL(url).toString(); // normalize
			img = await env.BROWSER_KV_DEMO.get(url, { type: "arrayBuffer" });
			if (img === null) {
				const browser = await puppeteer.launch(env.MYBROWSER);
				const page = await browser.newPage();
				await page.goto(url);
				img = (await page.screenshot()) as Buffer;
				await env.BROWSER_KV_DEMO.put(url, img, {
					expirationTtl: 60 * 60 * 24,
				});
				await browser.close();
			}
			return new Response(img, {
				headers: {
					"content-type": "image/jpeg",
				},
			});
		} else {
			return new Response(
				"Please add an ?url=https://example.com/ parameter"
			);
		}
	},
};

This Worker instantiates a browser using Puppeteer, opens a new page, navigates to what you put in the "url" parameter, takes a screenshot of the page, stores the screenshot in KV, closes the browser, and responds with the JPEG image of the screenshot.

If your Worker is running in production, it will store the screenshot to the production KV namespace. If you are running wrangler dev, it will store the screenshot to the dev KV namespace.

If the same "url" is requested again, it will use the cached version in KV instead, unless it expired.

​​ 6. Test

Run npx wrangler dev --remote to test your Worker locally before deploying to Cloudflare’s global network.

To test taking your first screenshot, go to the following URL:

<LOCAL_HOST_URL>/?url=https://example.com

​​ 7. Deploy

Run npx wrangler deploy to deploy your Worker to the Cloudflare global network.

To take your first screenshot, go to the following URL:

<YOUR_WORKER>.<YOUR_SUBDOMAIN>.workers.dev/?url=https://example.com

​​ Related resources

• Other Puppeteer examples Open external link