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Node.js Code Execution with ROMs

This guide explains how to deploy TypeScript/JavaScript functions as auxiliary Read-Only Memory (ROM) images, then load them dynamically in a Node.js runtime. With Unikraft Cloud, you can create a base image with a generic runtime, package custom code as ROMs, and attach different ROMs to instances of the same base image.

Prerequisites

1. Install the CLI: Use the unikraft CLI or the legacy kraft CLI. You need a BuildKit builder. The easiest way is via Docker. Alternatively, set up and use BuildKit directly, see the quick start.

2. Clone the examples repository and cd into the examples/node-code-execution directory:

   Code
   git clone https://github.com/unikraft-cloud/examples
   cd examples/node-code-execution/

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

Deployment Workflow

Package the base image

First, package and push the base Node.js image (see server.ts for the runtime implementation):

The server implementation in server.ts is a simple Node.js application that listens for HTTP requests and executes JavaScript code from the attached ROM, if available. There is a little tweak—right before loading the ROM code and starting the server, it writes 1 to the special file /uk/libukp/template_instance (see /platform/instances#instance-templates), triggering a conversion of the instance into a template.

Create an instance template from the base image

Create an instance that uses the base Node.js image without any ROM attached:

The output shows the instance details:

This instance is short-lived, since right before the server starts, it triggers a conversion into a template. To check that the template is ready, run:

Package the ROMs

Create and push the ROMs with the code (see rom1/fs/rom.js and rom2/fs/rom.ts):

Create instances from the template with different ROMs attached

Create a new instance from the template, attaching the first ROM:

Create another instance from the same template, but with the second ROM attached:

List the instances and note their FQDN values:

Test both instances:

Code
curl https://sparkling-dawn-syowlbtj.fra.unikraft.app
curl https://nameless-wood-gw7pbnls.fra.unikraft.app

Code
Bye, World!
Auf Wiedersehen!

Learn more

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

Or visit the CLI Reference or the legacy CLI Reference.