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Example apps

Perl HTTP Server

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

1. Install the unikraft CLI. You need a BuildKit builder. The easiest way to get one is via Docker. Alternatively, you can also directly set up and use BuildKit, see the quick start.

2. Clone the examples repository and cd into the examples/httpserver-perl5.42/ directory:

   Code
   git clone https://github.com/unikraft-cloud/examples
   cd examples/httpserver-perl5.42/

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

Code
unikraft login

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

Code
unikraft build . --output <my-org>/httpserver-perl542:latest
unikraft run --metro fra \
  -m 512M \
  -p 443:8080/tls+http \
  --scale-to-zero policy=on,cooldown-time=1000 \
  --image <my-org>/httpserver-perl542:latest

The output shows the instance address and other details:

Code
metro:        fra
name:         httpserver-perl542-xue8j
uuid:         59d08bbc-cbb7-4c6b-a2cb-847828845db9
state:        starting
image:        <my-org>/httpserver-perl542
resources:
  memory:     512MiB
  vcpus:      1
service:
  uuid:       b62c0c0a-2de6-9068-1e93-223fa8f1edbf
  name:       fragrant-water-wau08gaw
  domains:
  - fqdn:     fragrant-water-wau08gaw.fra.unikraft.app
networks:
- uuid:       22bdfc9c-2f69-eb7e-5b5e-929aba51a2c0
  private-ip: 10.0.1.161
  mac:        12:b0:d4:aa:c1:98
timestamps:
  created:    just now

In this case, the instance name is httpserver-perl542-xue8j and the address is https://fragrant-water-wau08gaw.fra.unikraft.app. They're different for each run.

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

Code
curl https://fragrant-water-wau08gaw.fra.unikraft.app

Code
Hello, World!

You can list information about the instance by running:

Code
unikraft instances list

Code
METRO  NAME                      STATE    IMAGE                        ARGS  MEMORY  VCPUS  FQDN                                      CREATED
fra    httpserver-perl542-xue8j  standby  <my-org>/httpserver-perl542        512MiB  1      fragrant-water-wau08gaw.fra.unikraft.app  2 minutes ago

When you list your instances, you might notice they show as standby. This is normal behavior and means the instance is using Unikraft Cloud's scale-to-zero feature that saves resources when there is no traffic. To check your instance is working, open two terminals and use these commands to watch the status:

Code
unikraft instance list --watch
# In another terminal, make requests
curl https://fragrant-water-wau08gaw.fra.unikraft.app

It switches to "running" then back to "standby."

When done, you can remove the instance:

Code
unikraft instances delete httpserver-perl542-xue8j

Customize your app

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

• server.pl: the actual Perl HTTP server implementation
• 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.pl 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
unikraft --help

Or visit the CLI Reference.