Copy page

Example apps

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 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/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, 🇩🇪):

Code
unikraft login

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

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

The output shows the instance address and other details:

Code
metro:        fra
name:         spin-wagi-http-is72r
uuid:         045c1bda-0f2e-4f8b-98c7-a208bfa7d143
state:        starting
image:        <my-org>/spin-wagi-http
resources:
  memory:     4096MiB
  vcpus:      1
service:
  uuid:       9b5b88fd-16ce-3db6-a828-ee885647d820
  name:       damp-bobo-wg43p36e
  domains:
  - fqdn:     damp-bobo-wg43p36e.fra.unikraft.app
networks:
- uuid:       db3851f6-ace1-8601-b6fa-925b7fdf8390
  private-ip: 10.0.28.16
  mac:        12:b0:fc:f5:09:d5
timestamps:
  created:    just now

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:

Code
unikraft instances list

Code
METRO  NAME                  STATE    IMAGE                    ARGS  MEMORY  VCPUS  FQDN                                 CREATED
fra    spin-wagi-http-is72r  running  <my-org>/spin-wagi-http        4.0GiB  1      damp-bobo-wg43p36e.fra.unikraft.app  2 minutes ago

When done, you can remove the instance:

Code
unikraft instances delete spin-wagi-http-is72r

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:

Code
unikraft --help

Or visit the CLI Reference.