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Deploy static web content with 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:

  1. Install the kraft CLI tool and a container runtime engine, e.g. Docker.

  2. Clone the examples repository and cd into the examples/caddy/ directory:

Terminal window
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:

Terminal window
# 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:

Terminal window
kraft cloud deploy -p 443:2015 .

The output shows the instance URL and other details:

Terminal window
[] 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.

Terminal window
curl https://frosty-sky-vz8kwsmb.fra0.kraft.host
Hello World!

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

Terminal window
kraft cloud instance list
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:

Terminal window
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
spec: v0.6
runtime: caddy:latest
rootfs: ./rootfs

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:

<!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:

Terminal window
kraft cloud --help

Or visit the CLI Reference.