# Wazero

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

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{/* THIS FILE WAS AUTOGENERATED FROM THE PUBLIC EXAMPLE REPOSITORY. DO NOT EDIT THIS FILE DIRECTLY. */}


This example comes from [Wazero's "import go" example](https://github.com/tetratelabs/wazero/tree/main/examples/import-go)
and shows how to define, import and call a wasm blob from Go and run it on Unikraft Cloud.

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/wazero-import-go/` directory:

```bash
git clone https://github.com/unikraft-cloud/examples
cd examples/wazero-import-go/
```

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>/wazero-import-go:latest
unikraft run --scale-to-zero policy=on,cooldown-time=1000 --metro fra -p 443:8080/tls+http -m 512M --image <my-org>/wazero-import-go:latest
```

```bash title="kraft"
kraft cloud deploy --scale-to-zero on --scale-to-zero-cooldown 1s -p 443:8080/tls+http -M 512Mi .
```

</CodeTabs>

The output shows the instance address and other details:

<CodeTabs syncKey="cli">

```ansi title="unikraft"
metro:        fra
name:         wazero-import-go-r4dx8
uuid:         a763e1c3-bb38-475f-95b6-1e78d8ca74fc
state:        starting
image:        <my-org>/wazero-import-go
resources:
  memory:     512MiB
  vcpus:      1
service:
  uuid:       f38a171d-e283-24ca-1158-c7907948071e
  name:       cool-morning-camrrhsa
  domains:
  - fqdn:     cool-morning-camrrhsa.fra.unikraft.app
networks:
- uuid:       bc4bb64c-8185-3b83-8693-b1464ab4723e
  private-ip: 10.0.6.7
  mac:        12:b0:05:55:02:fe
timestamps:
  created:    just now
```

```ansi title="kraft"
[●] Deployed successfully!
 │
 ├───────── name: wazero-import-go-r4dx8
 ├───────── uuid: a763e1c3-bb38-475f-95b6-1e78d8ca74fc
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: https://cool-morning-camrrhsa.fra.unikraft.app
 ├──────── image: oci://unikraft.io/<my-org>/wazero-import-go@sha256:865700d358ffb2751888798ec8f302d23310b1fcf84f4d3f17f79fc25ff71153
 ├─────── memory: 512 MiB
 ├────── service: cool-morning-camrrhsa
 ├─ private fqdn: wazero-import-go-r4dx8.internal
 └─── private ip: 10.0.6.7
```

</CodeTabs>

In this case, the instance name is `wazero-import-go-r4dx8` and the address is `https://cool-morning-camrrhsa.fra.unikraft.app`.
They're different for each run.

Use `curl` to query the Unikraft Cloud instance of the Go/wazero server:

```bash
curl https://cool-morning-camrrhsa.fra.unikraft.app
```

```text
println >> 24
log_i32 >> 24
```

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    wazero-import-go-r4dx8  running  <my-org>/wazero-import-go        512MiB  1      cool-morning-camrrhsa.fra.unikraft.app  2 minutes ago
```

```ansi title="kraft"
NAME                    FQDN                                    STATE    STATUS         IMAGE                                             MEMORY   VCPUS  ARGS  BOOT TIME
wazero-import-go-r4dx8  cool-morning-camrrhsa.fra.unikraft.app  running  1 minutes ago  oci://unikraft.io/<my-org>/wazero-import-go@s...  512 MiB  1            20.04 ms
```

</CodeTabs>

When done, you can remove the instance:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances delete wazero-import-go-r4dx8
```

```bash title="kraft"
kraft cloud instance remove wazero-import-go-r4dx8
```

</CodeTabs>

## Background

WebAssembly has neither a mechanism to get the current year, nor one to print to the console, so this example defines these in Go.
Like Go, WebAssembly functions are namespaced into modules instead of packages.
With Go only exported functions can import into another module.
`age-calculator.go` shows how to export functions using [HostModuleBuilder](https://pkg.go.dev/github.com/tetratelabs/wazero#HostModuleBuilder) and how a WebAssembly module defined in its [text format](https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#text-format%E2%91%A0) imports it.
This only uses the text format for demonstration purposes, to show you what's going on.
It's likely, you will use another language to compile a Wasm (WebAssembly Module) binary, such as TinyGo.
Regardless of how wasm produces, the export/import mechanics are the same!

### Using WASI

WebAssembly System Interface (WASI) is a modular system interface for WebAssembly.
This uses an ad-hoc Go-defined function to print to the console.
An emerging specification standardizes system calls (like Go's [x/sys](https://pkg.go.dev/golang.org/x/sys/unix)) called WebAssembly System Interface [(WASI)](https://github.com/WebAssembly/WASI).
While this isn't yet a W3C standard, wazero includes a [wasi package](https://pkg.go.dev/github.com/tetratelabs/wazero/wasi).

## Customize your app

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

* `agecalculator.go`: The Go web server that calls the WASM/Wazero blog for the age calculation
* `Kraftfile`: the Unikraft Cloud specification
* `Dockerfile`: the Docker-specified app filesystem

## 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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