Flatpak with Perl

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When you’ve had experience installing software on Linux before, you probably know how much frustration it can cause: one application wants one version of a library installed in your system, while the second one wants an incompatible one, and this disables both of them.

What’s new

Flatpak is a revolutionary new technology that will change the way we are installing and running programs on our Linux computers. Unlike traditional packages that need files unique to your distro, Flatpak packages contain both the application itself and all the dependencies it requires.

Why It Is Important

Compatibility: Any Flatpak application works the same way on Ubuntu or Fedora, in other words, Flatpak applications are truly universal.
Security: Apps run in a sandbox that restricts their access to your data and hardware resources unless you give them permission.
No Dependency Conflicts: You may update your Flatpak application without worrying about breaking the rules of your system or conflicting with your existing software.

In general terms, Flatpak provides us with a universal, easy, and safe app store experience on Linux.

Runtimes

Applications cannot operate autonomously; they require system programs, essential libraries, and also graphics drivers all configured together. For accomplishing this, Flatpak makes use of Runtimes.

Applications

In computer jargon, an application refers to the piece of software that you wish to execute (like Spotify or LibreOffice).

OSTree

If you are familiar with Git, you will find something similar with OSTree. OSTree can also be called "Git for operating system binaries."

The Sandbox

In order to maintain high level protection of your system, Flatpak uses a special technology called Bubblewrap which is a low-level utility that provides separation of applications from the operating system.

It is common practice among experts to compare Flatpak and Docker owing to the use of containers and isolation of applications. Nevertheless, the tools have been created for two different worlds.

In the real world, Flatpak solution suits to the desktop environment, while Docker has the application that fits perfectly to the server environment.

Docker is about creating copies of server environments for the same server to work on many platforms.

Flatpak is focused on creating copies of applications for their usage in many different platforms.

Flathub

Flathub is the basic repository for the applications developed along the Flatpak platform.

The term Flatpak refers to the way we create and install applications on Linux whereas Flathub is somewhat similar to that of an online store that sells the application and other products. Flathub could be thought of as equivalent to Google play store or Apple App Store.

If you want to know more about the importance of Flathub, you should know how the Linux software was traditionally distributed.

Previously, when a developer created a software application, he/she used to manually create a separate installer for each Linux distribution using different formats for Ubuntu/Debian package(.deb), Fedora(RPM), etc.

In one of my previous blog posts, I wrote about building a Deb package on Linux.

Now with Flathub, developers can create an application only once using Flatpak and upload it to the Flathub store.

It allows other users from any distribution to install that application in no time.

If Flatpak is like the shipping container that holds the product, Flathub is like the world-famous shipping yard where all shipping containers are kept in order before they are shipped away to their destinations. Without Flathub, Flatpak is just another application framework; with Flathub, it becomes a complete shopping platform.

Let’s do some real work:

Step 1: Prepare Manifest File

Make sure your org.example.cpanapp.yaml file looks exactly like this. This consolidated version specifies the right runtime environment, pre-loads the hidden dependencies, and maps the internal Perl paths.

$ cat org.example.cpanapp.yaml
id: org.example.cpanapp
runtime: org.freedesktop.Sdk
runtime-version: '24.08'
sdk: org.freedesktop.Sdk
command: app.pl

build-options:
  env:
    PERL5LIB: /app/lib/perl5:/app/share/perl5

modules:
  - name: perl-module-build
    buildsystem: simple
    build-commands:
      - perl Build.PL --install_base=/app
      - ./Build
      - ./Build install
    sources:
      - type: archive
        url: https://cpan.metacpan.org/authors/id/L/LE/LEONT/Module-Build-0.4234.tar.gz
        sha256: 66aeac6127418be5e471ead3744648c766bd01482825c5b66652675f2bc86a8f

  - name: perl-text-asciitable
    buildsystem: simple
    build-commands:
      - perl Makefile.PL INSTALL_BASE=/app
      - make
      - make install
    sources:
      - type: archive
        url: https://cpan.metacpan.org/authors/id/L/LU/LUNATIC/Text-ASCIITable-0.22.tar.gz
        sha256: e4d39537db35d75eb88032d2d26a707733fe33b6baeb212f9c733fc4bff07e43

  - name: perl-main-app
    buildsystem: simple
    build-commands:
      - install -D app.pl /app/bin/app.pl
    sources:
      - type: dir
        path: src

Step 2: Prepare Simple App

File: src/app.pl

#!/usr/bin/env perl
use strict;
use warnings;
use lib '/app/lib/perl5';
use Text::ASCIITable;

print "========================================\n";
print "   Perl Flatpak with CPAN Dependency    \n";
print "========================================\n";

# Create a table using the bundled CPAN module
my $t = Text::ASCIITable->new({ headingText => 'Flatpak Environment Sandbox' });

$t->setCols('Component', 'Status', 'Details');
$t->addRow('Perl Core', 'Loaded', $]);
$t->addRow('Text::ASCIITable', 'Loaded', $Text::ASCIITable::VERSION);
$t->addRow('Sandbox Path', 'Secure', '/app');

print $t;

Step 3: Add Flathub Remote

To ensure your local user profile can download the required building blocks from the Flatpak store without needing root/sudo privileges.

$ flatpak remote-add --user --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo

Step 4: Install Freedesktop SDK

Download the modern 24.08 environment development kit where the underlying perl runtime binary lives:

$ flatpak install --user flathub org.freedesktop.Sdk//24.08

Step 5: Build / Install App

This command downloads the CPAN modules, compiles them inside the network-isolated sandbox container, registers your local src/app.pl file, and installs the finished app bundle cleanly into your user space:

$ flatpak-builder --user --install --force-clean build-dir org.example.cpanapp.yaml

Step 6: Run App

Launch your newly containerised Perl application from anywhere in your terminal:

$ flatpak run org.example.cpanapp
========================================
   Perl Flatpak with CPAN Dependency
========================================
.--------------------------------------.
|      Flatpak Environment Sandbox     |
+------------------+--------+----------+
| Component        | Status | Details  |
+------------------+--------+----------+
| Perl Core        | Loaded | 5.040004 |
| Text::ASCIITable | Loaded |     0.22 |
| Sandbox Path     | Secure | /app     |
'------------------+--------+----------'

Happy Hacking !!!