Guides

Perl

In this guide we create and deploy a simple Perl-based HTTP web server. 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/http-perl5.38/ directory:

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git clone https://github.com/kraftcloud/examples
cd examples/http-perl5.38/

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:

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kraft cloud deploy -p 443:8080 -M 512 .

The output shows the instance URL and other details:

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[●] Deployed successfully!
 │
 ├────────── name: http-perl538-1p4ml
 ├────────── uuid: eabb0080-0065-40ff-81a8-f790f1b218ee
 ├───────── state: running
 ├─────────── url: https://cold-brook-ba71jc16.fra0.kraft.host
 ├───────── image: http-perl538@sha256:8c2c1f536b349c24e04ab4fec508b69f7f2349302d42a02855318ee55c12e37c
 ├───── boot time: 64.56 ms
 ├──────── memory: 512 MiB
 ├─────── service: cold-brook-ba71jc16
 ├── private fqdn: http-perl538-1p4ml.internal
 ├──── private ip: 172.16.3.3
 └────────── args: /usr/bin/perl /usr/src/server.pl

In this case, the instance name is http-perl538-1p4ml and the URL is https://cold-brook-ba71jc16.fra0.kraft.host. They are different for each run.

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

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curl https://cold-brook-ba71jc16.fra0.kraft.host

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Hello, World!

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

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kraft cloud instance list

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NAME                FQDN                                 STATE    CREATED AT      IMAGE                                  MEMORY   ARGS                              BOOT TIME
http-perl538-1p4ml  cold-brook-ba71jc16.fra0.kraft.host  stopped  37 seconds ago  http-perl538@sha256:8c2c1f536b349c...  512 MiB  /usr/bin/perl /usr/src/server.pl  64556us

When done, you can remove the instance:

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kraft cloud instance remove http-perl538-1p4ml

Customize your Application

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

• server.pl: the actual Perl HTTP server
• Kraftfile: the Unikraft Cloud specification
• Dockerfile: the Docker-specified application filesystem

The following options are available for customizing the application:

• If only updating the implementation in the server.pl source file, no other change is required.

• If new files are added, these have to be copied in the application filesystem, using the COPY command in the Dockerfile.

• If a new Perl source files is added, update the cmd line in the Kraftfile and replace server.pl to run that file when creating the instance.

• More extensive changes may require expanding the Dockerfile with additional Dockerfile commands.

Learn More

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

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kraft cloud --help

Or visit the CLI Reference.