# Spin

import { Tabs, TabsContent, TabsList, TabsTrigger } from "zudoku/ui/Tabs"

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This guide explains how to create and deploy a simple Spin HTTP app.
This guide comes from  [Spin's `spin-wagi-http` example](https://github.com/fermyon/spin/tree/v2.1.0/examples/spin-wagi-http).
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](/cli/unikraft) or the legacy [kraft CLI](https://unikraft.org/docs/cli/install).
   You need a [BuildKit](https://github.com/moby/buildkit) builder. The easiest way to get one is via [Docker](https://docs.docker.com/engine/install/).
   Alternatively, you can also directly set up and use BuildKit, see the [quick start](https://github.com/moby/buildkit#quick-start).

:::note
The unikraft CLI is the current standard, while kraft is the legacy version.
Choose one of the CLIs below and only run the commands associated with it for the rest of this guide.
:::

2. Clone the [`examples` repository](https://github.com/unikraft-cloud/examples) and `cd` into the `examples/spin-wagi-http/` directory:

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

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

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft login
```

```bash title="kraft"
# Set Unikraft Cloud access token
export UKC_TOKEN=token
# Set metro to Frankfurt, DE
export UKC_METRO=fra
```

</CodeTabs>

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

<CodeTabs syncKey="cli">

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

```bash title="kraft"
kraft cloud deploy --scale-to-zero on --scale-to-zero-stateful --scale-to-zero-cooldown 1s -p 443:3000/tls+http -M 4Gi .
```

</CodeTabs>

The output shows the instance address and other details:

<CodeTabs syncKey="cli">

```ansi title="unikraft"
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
```

```ansi title="kraft"
[●] Deployed successfully!
 │
 ├───────── name: spin-wagi-http-is72r
 ├───────── uuid: 045c1bda-0f2e-4f8b-98c7-a208bfa7d143
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: https://damp-bobo-wg43p36e.fra.unikraft.app
 ├──────── image: oci://unikraft.io/<my-org>/spin-wagi-http@sha256:57a5151996d83332af6da521e1cd92271a8c3ac7ae26bc44a7c0dbbc0a30e577
 ├─────── memory: 4096 MiB
 ├────── service: damp-bobo-wg43p36e
 ├─ private fqdn: spin-wagi-http-is72r.internal
 └─── private ip: 10.0.28.16
```

</CodeTabs>

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:

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

Hello, Fermyon!
```

And `curl` the goodbye route:

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

Goodbye, Fermyon!
```

You can list information about the instance by running:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances list
```

```bash title="kraft"
kraft cloud instance list
```

</CodeTabs>

<CodeTabs syncKey="cli">

```ansi title="unikraft"
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
```

```ansi title="kraft"
NAME                  FQDN                                 STATE    STATUS        IMAGE                                              MEMORY   VCPUS  ARGS  BOOT TIME
spin-wagi-http-is72r  damp-bobo-wg43p36e.fra.unikraft.app  running  1 minute ago  oci://unikraft.io/<my-org>/spin-wagi-http@sha2...  4.0 GiB  1            300.06 ms
```

</CodeTabs>

When done, you can remove the instance:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances delete spin-wagi-http-is72r
```

```bash title="kraft"
kraft cloud instance remove spin-wagi-http-is72r
```

</CodeTabs>

## 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](https://erofs.docs.kernel.org/).

* `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](https://docs.docker.com/engine/reference/builder/)).

## Learn more

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

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft --help
```

```bash title="kraft"
kraft cloud --help
```

</CodeTabs>

Or visit the [CLI Reference](/cli/unikraft) or the [legacy CLI Reference](/cli/kraft/overview).
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