Copy page

Example apps

Headless Browsers: Puppeteer HTTP Server

Headless browsers power web scraping, automated testing, search engine optimization (SEO) rendering, screenshotting, and document generation. They are resource-intensive and usually run in short bursts, which makes them a good fit for instances that boot in milliseconds and scale to zero between jobs.

This guide shows you how to use Puppeteer, a Node.js library which provides a high-level API to control browsers, including the option to run them headless (no UI). The example wraps Puppeteer in an Express HTTP server that renders a URL or an HTML payload to PDF.

To run it, follow these steps:

1. Install the unikraft CLI. You need a BuildKit builder. The easiest way to get one is via Docker. Alternatively, you can also directly set up and use BuildKit, see the quick start.

2. Clone the examples repository and cd into the examples/httpserver-node-express-puppeteer/ directory:

   Code
   git clone https://github.com/unikraft-cloud/examples
   cd examples/httpserver-node-express-puppeteer/

Make sure to log into Unikraft Cloud and pick a metro close to you. This guide uses fra (Frankfurt, 🇩🇪):

Code
unikraft login

When done, invoke the following command to deploy this app on Unikraft Cloud:

Code
unikraft build . --output <my-org>/httpserver-node-express-puppeteer:latest
unikraft run --metro fra \
  -m 4G \
  -p 443:3000/tls+http \
  --scale-to-zero policy=idle,cooldown-time=1000,stateful=true \
  --image <my-org>/httpserver-node-express-puppeteer:latest

The output shows the instance address and other details:

Code
metro:        fra
name:         httpserver-node-express-puppeteer-7afg3
uuid:         7bb479d7-5b3e-444f-b07c-eae4da6f57cc
state:        starting
image:        <my-org>/httpserver-node-express-puppeteer
resources:
  memory:     4096MiB
  vcpus:      1
service:
  uuid:       996b9cc1-5a51-e707-d443-5c98ea86ded8
  name:       little-snow-7qwu6vv5
  domains:
  - fqdn:     little-snow-7qwu6vv5.fra.unikraft.app
networks:
- uuid:       034fa25e-9154-7842-ccdd-289256cc7a17
  private-ip: 10.0.3.1
  mac:        12:b0:8f:3c:f5:16
timestamps:
  created:    just now

In this case, the instance name is httpserver-node-express-puppeteer-7afg3. They're different for each run.

Use a browser to access the landing page of the Puppeteer (that uses ExpressJS). The app and the landing page are part of this repository.

In the example run above the landing page is at https://nameless-fog-0tvh1uov.fra.unikraft.app. You can use the landing page to generate the PDF version of a remote page.

You can list information about the instance by running:

Code
unikraft instances list

Code
METRO  NAME                                     STATE    IMAGE                                       ARGS  MEMORY   VCPUS  FQDN                                    CREATED
fra    httpserver-node-express-puppeteer-7afg3  running  <my-org>/httpserver-node-express-puppeteer        4096MiB  1      nameless-fog-0tvh1uov.fra.unikraft.app  2 minutes ago

When done, you can remove the instance:

Code
unikraft instances delete httpserver-node-express-puppeteer-7afg3

Customize your deployment

The current deployment uses an ExpressJS service that uses the PDF generating functionality of Puppeteer. Customizing the deployment means updating the service, such as adding new functionalities provided by Puppeteer. You can update the service to provide a REST-like interface.

Learn more

Use the --help option for detailed information on using Unikraft Cloud:

Code
unikraft --help

Or visit the CLI Reference.