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Guides

Spin

This guide explains how to create and deploy a simple Spin HTTP app. This guide comes from Spin's spin-wagi-http example. It shows how to run a Spin app serving routes from two programs written in different languages (Rust and C++).

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/spin-wagi-http/ directory:

Code
git clone https://github.com/unikraft-cloud/examples
cd examples/spin-wagi-http/

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 spin-wagi-http-is72r and the address is https://damp-bobo-wg43p36e.fra.unikraft.app. They're different for each run.

Then curl the hello route:

Code
curl -i https://damp-bobo-wg43p36e.fra.unikraft.app/hello

Hello, Fermyon!

And curl the goodbye route:

Code
curl -i https://damp-bobo-wg43p36e.fra.unikraft.app/goodbye

Goodbye, Fermyon!

You can list information about the instance by running:

When done, you can remove the instance:

Customize your app

To customize the app, update the files in the repository, listed below:

• wagi-http-cpp: C++ server handling the hello route
• http-rust: Rust server handling the goodbye route
• Kraftfile: the Unikraft Cloud specification
• Dockerfile: the Docker-specified app filesystem
• spin.toml: The Spin TOML configuration file

Lines in the Kraftfile have the following roles:

• spec: v0.7: The current Kraftfile specification version is 0.7.

• runtime: base-compat:latest: The runtime kernel to use is the base compatibility kernel.

• rootfs: Build the app root filesystem. source: ./Dockerfile means the filesystem is built using the Dockerfile. format: erofs means the filesystem type is EROFS.

• cmd: ["/usr/bin/spin", "up", "--from", "/app/spin.toml", "--listen", "0.0.0.0:3000"]: Use spin as the command to start the app, with the given parameters.

The following options are available for customizing the app:

• If only updating the existing files under the wagi-http-cpp and http-rust directories, you don't need to make any other changes.

• If you create any new source files, copy them into the app filesystem by using the COPY command in the Dockerfile.

• More extensive changes may require extending the Dockerfile (see Dockerfile syntax reference).

Learn more

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

Or visit the CLI Reference or the legacy CLI Reference.