# Ruby HTTP Server

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

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This guide explains how to create and deploy a simple Ruby-based HTTP web server.
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/httpserver-ruby3.2/` directory:

```bash
git clone https://github.com/unikraft-cloud/examples
cd examples/httpserver-ruby3.2/
```

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>/httpserver-ruby32:latest
unikraft run --scale-to-zero policy=on,cooldown-time=1000 --metro fra -p 443:8080/tls+http -m 256M --image <my-org>/httpserver-ruby32:latest
```

```bash title="kraft"
kraft cloud deploy --scale-to-zero on --scale-to-zero-cooldown 1s -p 443:8080/tls+http -M 256Mi .
```

</CodeTabs>

The output shows the instance address and other details:

<CodeTabs syncKey="cli">

```ansi title="unikraft"
metro:        fra
name:         httpserver-ruby32-s6l8n
uuid:         b1ebbbc0-5efa-476c-adb6-99866773245c
state:        starting
image:        <my-org>/httpserver-ruby32
resources:
  memory:     256MiB
  vcpus:      1
service:
  uuid:       bcc07c7c-9289-11f4-6e3d-8f7fdde45256
  name:       silent-resonance-1jtz5c66
  domains:
  - fqdn:     silent-resonance-1jtz5c66.fra.unikraft.app
networks:
- uuid:       50203783-cf51-81d1-aa2d-615f939043af
  private-ip: 10.0.3.3
  mac:        12:b0:0a:4f:7a:84
timestamps:
  created:    just now
```

```ansi title="kraft"
[●] Deployed successfully!
 │
 ├───────── name: httpserver-ruby32-s6l8n
 ├───────── uuid: b1ebbbc0-5efa-476c-adb6-99866773245c
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: https://silent-resonance-1jtz5c66.fra.unikraft.app
 ├──────── image: oci://unikraft.io/<my-org>/httpserver-ruby32@sha256:4cf3b341898e6ebff18ff2b68353ef872dded650c9d16a6f005a8fbe8a7cbb3d
 ├─────── memory: 256 MiB
 ├────── service: silent-resonance-1jtz5c66
 ├─ private fqdn: httpserver-ruby32-s6l8n.internal
 └─── private ip: 10.0.3.3
```

</CodeTabs>

In this case, the instance name is `httpserver-ruby32-s6l8n` and the address is `https://silent-resonance-1jtz5c66.fra.unikraft.app`.
They're different for each run.

Use `curl` to query the Unikraft Cloud instance of the Ruby-based HTTP web server:

```bash
curl https://silent-resonance-1jtz5c66.fra.unikraft.app
```

```text
Hello, World!
```

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    httpserver-ruby32-s6l8n  running  <my-org>/httpserver-ruby32        256MiB  1      silent-resonance-1jtz5c66.fra.unikraf…  2 minutes ago
```

```ansi title="kraft"
NAME                     FQDN                                        STATE    STATUS          IMAGE                                                    MEMORY   VCPUS  ARGS  BOOT TIME
httpserver-ruby32-s6l8n  silent-resonance-1jtz5c66.fra.unikraft.app  running  12 minutes ago  oci://unikraft.io/<my-org>/httpserver-ruby32@sha256:...  256 MiB  1            71.19 ms
```

</CodeTabs>

When done, you can remove the instance:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances delete httpserver-ruby32-s6l8n
```

```bash title="kraft"
kraft cloud instance remove httpserver-ruby32-s6l8n
```

</CodeTabs>

## Customize your app

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

* `server.rb`: the actual Ruby HTTP server
* `Kraftfile`: the Unikraft Cloud specification
* `Dockerfile`: the Docker-specified app filesystem

The following options are available for customizing the app:

* If you only update the implementation in the `server.rb` source file, 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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