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Node WebSocket Server

WebSocket is a bidirectional communication protocol over TCP, compatible with HTTP. This example builds an echo-reply WebSocket server in Node.

To run this example, follow these steps:

1. Install the CLI. Use the unikraft CLI or the legacy kraft 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/node21-websocket/ directory:

Code
git clone https://github.com/unikraft-cloud/examples
cd examples/node21-websocket/

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

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

The output shows the instance address and other details:

In this case, the instance name is node21-websocket-j2x9r and the address is https://lively-breeze-hp3wx6yt.fra.unikraft.app. They're different for each run.

The command will build the files in the current directory.

After deploying, you can query the service with a WebSocket client, such as wscat. Install wscat with npm:

Code
npm install -g wscat

Then query the WebSocket server deployed on Unikraft Cloud, using its URL:

Code
wscat --connect wss://<NAME>.<METRO>.unikraft.app

Then enter messages, that will be replied by the server.

You can list information about the instance by running:

When done, you can remove the instance:

Learn more

• WebSocket documentation
• ws: A Node.js WebSocket library
• Unikraft Cloud's Documentation
• Building Dockerfile Images with Buildkit

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

Or visit the CLI Reference or the legacy CLI Reference.