Guides

Lua

This guide explains how to create and deploy a simple Lua-based HTTP web server. To run this example, follow these steps:

1. Install the kraft CLI tool and a container runtime engine, for example Docker.

2. Clone the examples repository and cd into the examples/http-lua5.1/ directory:

Code(bash)
 
git clone https://github.com/kraftcloud/examples
cd examples/http-lua5.1/

Make sure to log into Unikraft Cloud by setting your token and a metro close to you. This guide uses fra (Frankfurt, 🇩🇪):

Code(bash)
 
# Set Unikraft Cloud access token
export UKC_TOKEN=token
# Set metro to Frankfurt, DE
export UKC_METRO=fra

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

Code(bash)
 
kraft cloud deploy -p 443:8080 .

The output shows the instance address and other details:

Code(ansi)
 
[●] Deployed successfully!
 │
 ├────────── name: http-lua51-ma2i9
 ├────────── uuid: e7389eee-9808-4152-b2ec-1f3c0541fd05
 ├───────── state: running
 ├─────────── url: https://young-night-5fpf0jj8.fra.unikraft.app
 ├───────── image: http-lua51@sha256:278cb8b14f9faf9c2702dddd8bfb6124912d82c11b4a2c6590b6e32fc4049472
 ├───── boot time: 15.09 ms
 ├──────── memory: 128 MiB
 ├─────── service: young-night-5fpf0jj8
 ├── private fqdn: http-lua51-ma2i9.internal
 ├──── private ip: 172.16.3.3
 └────────── args: /usr/bin/lua /http_server.lua

In this case, the instance name is http-lua51-ma2i9 and the address is https://young-night-5fpf0jj8.fra.unikraft.app. They're different for each run.

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

Code(bash)
 
curl https://young-night-5fpf0jj8.fra.unikraft.app

Code(text)
 
Hello, World!

You can list information about the instance by running:

Code(bash)
 
kraft cloud instance list

Code(text)
 
NAME              FQDN                                  STATE    CREATED AT    IMAGE                                    MEMORY   ARGS                           BOOT TIME
http-lua51-ma2i9  young-night-5fpf0jj8.fra.unikraft.app  running  1 minute ago  http-lua51@sha256:278cb8b14f9faf9c27...  128 MiB  /usr/bin/lua /http_server.lua  15094us

When done, you can remove the instance:

Code(bash)
 
kraft cloud instance remove http-lua51-ma2i9

Customize your app

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

• http_server.lua: the actual Lua 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 http_server.lua 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).

Learn more

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

Code(bash)
 
kraft cloud --help

Or visit the CLI Reference.