Guides

Caddy

This example uses Caddy, one of the most popular web servers. Caddy can be used with Unikraft / Unikraft Cloud to serve static web content.

To run this example, follow these steps:

Install the kraft CLI tool and a container runtime engine, e.g. Docker.
Clone the examples repository and cd into the examples/caddy/ directory:

Code
 
git clone https://github.com/kraftcloud/examples
cd examples/caddy/

Make sure to log into Unikraft Cloud by setting your token and a metro close to you. We use fra0 (Frankfurt, 🇩🇪) in this guide:

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# Set Unikraft Cloud access token
export UKC_TOKEN=token
# Set metro to Frankfurt, DE
export UKC_METRO=fra0

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

Code
 
kraft cloud deploy -p 443:2015 .

The output shows the instance URL and other details:

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[●] Deployed successfully!
 │
 ├────────── name: caddy-vhf4m
 ├────────── uuid: db624eff-4739-4500-873c-f7c58e4eefd7
 ├───────── state: running
 ├─────────── url: https://frosty-sky-vz8kwsmb.fra0.kraft.host
 ├───────── image: caddy@sha256:25df97e3c43147c683f31dd062d0fa75122358b596de5804ca246c4e8613dd56
 ├───── boot time: 20.18ms
 ├──────── memory: 128 MiB
 ├─────── service: frosty-sky-vz8kwsm
 ├── private fqdn: caddy-vhf4m.internal
 ├──── private ip: 172.16.6.2
 └────────── args: /usr/bin/caddy run --config /etc/caddy/Caddyfile

In this case, the instance name is caddy-vhf4m and the URL is https://frosty-sky-vz8kwsmb.fra0.kraft.host. They are different for each run.

Use curl to query the Unikraft Cloud instance of Caddy.

Code
 
curl https://frosty-sky-vz8kwsmb.fra0.kraft.host

Code
 
Hello World!

At any point in time, you can list information about the instance:

Code
 
kraft cloud instance list

Code
 
NAME                           FQDN                                      STATE    CREATED AT     IMAGE                               MEMORY   ARGS                                     BOOT TIME
caddy-vhf4m                    frosty-sky-vz8kwsmb.fra0.kraft.host      running  1 minute ago   caddy@sha25:25df97e3c43147c683f...  128 MiB  /usr/bin/caddy run --config /e...        20180us

When done, you can remove the instance:

Code
 
kraft cloud instance remove caddy-vhf4m

Customize your Application

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

Kraftfile: the Unikraft Cloud specification
rootfs/var/www/index.html: the index page of the content served
rootfs/etc/caddy/Caddyfile: the Caddy configuration file

Update the contents of the rootfs/var/www directory to serve different static web content. For example, you could change the contents of rootfs/var/www/index.html to:

Code
 
<!DOCTYPE html>
<html>
<head>
<title>Hello</title>
</head>
<body>
<h2>Hello, World!</h2>
</body>
</html>

After re-deploying the Caddy image on Unikraft Cloud, using curl or a browser to query it will present the new page contents.

The static web content located in the rootfs/var/www/ can of course be generated offline by tools like Jekyll or Hugo.

If required, you can also customize the configuration of Caddy in rootfs/etc/caddy/Caddyfile. You can set a new webroot (different than rootfs), or a different internal port, or a different index page, etc.

Learn More

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

Code
 
kraft cloud --help

Or visit the CLI Reference.

Last modified on September 9, 2025

Bun C++ Boost