# Spring Boot HTTP Server


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

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This guide explains how to create and deploy a Spring Boot 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).

2. Clone the [`examples` repository](https://github.com/unikraft-cloud/examples) and `cd` into the `examples/httpserver-java17-springboot3.5.x/` directory:

```bash
git clone https://github.com/unikraft-cloud/examples
cd examples/httpserver-java17-springboot3.5.x/
```

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-java17-springboot35x:latest
unikraft run --scale-to-zero policy=idle,cooldown-time=1000,stateful=true --metro fra -p 443:8080/tls+http -m 1G --image <my-org>/httpserver-java17-springboot35x:latest
```

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

</CodeTabs>

The output shows the instance address and other details:

<CodeTabs syncKey="cli">

```ansi title="unikraft"
metro:        fra
name:         httpserver-java17-springboot35x-qseeo
uuid:         b081166d-a2a0-43af-982d-1aa17f06b5c4
state:        starting
image:        <my-org>/httpserver-java17-springboot35x
resources:
  memory:     1024MiB
  vcpus:      1
service:
  uuid:       04f5b3ce-0aae-a50a-9d58-e6fa618b2cdc
  name:       long-dust-si7xsngk
  domains:
  - fqdn:     long-dust-si7xsngk.fra.unikraft.app
networks:
- uuid:       4bde3abf-faf8-3a14-ceb9-bc05e646dfac
  private-ip: 10.0.6.2
  mac:        12:b0:eb:ad:60:a2
timestamps:
  created:    just now
```

```ansi title="kraft"
[●] Deployed successfully!
 │
 ├───────── name: httpserver-java17-springboot35x-qseeo
 ├───────── uuid: b081166d-a2a0-43af-982d-1aa17f06b5c4
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: https://long-dust-si7xsngk.fra.unikraft.app
 ├──────── image: oci://unikraft.io/<my-org>/httpserver-java17-springboot35x@sha256:cc2f2ad18ce8e36b8e8f4debee096fef7b0bb8b47762575a2ba5a9de8199c64a
 ├─────── memory: 1024 MiB
 ├────── service: long-dust-si7xsngk
 ├─ private fqdn: httpserver-java17-springboot35x-qseeo.internal
 └─── private ip: 10.0.6.2
```

</CodeTabs>

In this case, the instance name is `httpserver-java17-springboot35x-qseeo` and the address is `https://long-dust-si7xsngk.fra.unikraft.app`.
They're different for each run.

Use `curl` to query the Spring Boot server's `hello` endpoint:

```bash
curl https://long-dust-si7xsngk.fra.unikraft.app/hello
```

```text
Hello World!
```

When done, you can remove the instance:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances delete httpserver-java17-springboot35x-qseeo
```

```bash title="kraft"
kraft cloud instance remove httpserver-java17-springboot35x-qseeo
```

</CodeTabs>

## Customize your app

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

* `DemoApplication.java`: the server
* `Kraftfile`: the Unikraft Cloud specification
* `Dockerfile`: the Docker-specified app filesystem

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`.
  `type: erofs` means the filesystem type is [EROFS](https://erofs.docs.kernel.org/).

* `cmd: ["/usr/lib/jvm/java-17-openjdk-amd64/bin/java", "-jar", "/usr/src/demo-0.0.1-SNAPSHOT.jar"]`: Use as the starting command of the instance.

Lines in the `Dockerfile` have the following roles:

* `FROM scratch`: Build the filesystem from the [`scratch` container image](https://hub.docker.com/_/scratch/), to [create a base image](https://docs.docker.com/build/building/base-images/).

* `COPY DemoApplication.java src/main/java/com/example/demo/`: Copy the server implementation file in the Docker filesystem.

The following options are available for customizing the app:

* If you only update the implementation in the `DemoApplication.java` 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/)).

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-java17-springboot35x-qseeo  running  <my-org>/httpserver-java17-springboot35x        1024MiB  1      long-dust-si7xsngk.fra.unikraft.app  2 minutes ago
```

```ansi title="kraft"
NAME                                   FQDN                                 STATE    STATUS        IMAGE                                                                  MEMORY   VCPUS  ARGS  BOOT TIME
httpserver-java17-springboot35x-qseeo  long-dust-si7xsngk.fra.unikraft.app  running  1 minute ago  oci://unikraft.io/<my-org>/httpserver-java17-springboot35x@sha256:...  1.0 GiB  1            421.30 ms
```

</CodeTabs>

When done, you can remove the instance:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances delete httpserver-java17-springboot35x-qseeo
```

```bash title="kraft"
kraft cloud instance remove httpserver-java17-springboot35x-qseeo
```

</CodeTabs>


## 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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