Creating a Flatpak

Ship your app easily to users.

We can also take care of distributing our PyQt application. Although the Python Package Index (PyPI) is probably the standard way to distribute a Python package, Flatpak should be more user friendly for Linux users than using command line tools such as pip.

Flatpaks are built locally using flatpak-builder. The tool checks out the source code and any of its custom dependencies, then builds it against a runtime (a collection of libraries shared between flatpaks). Since we already took care of the source code, all we need is to write a single file, the flatpak manifest, which describes everything needed to build the package.

Create a new flatpak manifest file simplemdviewer/org.kde.simplemdviewer.json:

{
    "id": "org.kde.simplemdviewer",
    "runtime": "org.kde.Platform",
    "runtime-version": "6.7",
    "sdk": "org.kde.Sdk",
    "base": "io.qt.PySide.BaseApp",
    "base-version": "6.7",
    "command": "simplemdviewer",
    "finish-args": [
    "--share=ipc",
    "--socket=fallback-x11",
    "--socket=wayland",
    "--device=dri",
    "--socket=pulseaudio"
    ],
    "modules": [
        "python3-markdown.json",
        {
            "name": "simplemdviewer",
            "buildsystem" : "simple",
            "build-commands" : [
                "python3 setup.py build",
                "python3 setup.py install --prefix=/app --root=/"
            ],
            "sources": [
                {
                    "type": "archive",
                    "path": "dist/org.kde.simplemdviewer-0.1.tar.gz"
                }
            ]
        }
    ],
    "cleanup-commands": [
        "/app/cleanup-BaseApp.sh"
    ]
}

Note

The Flatpak manifest for PySide uses the version 6.7 for the runtime and the base app, as opposed to PyQt which uses the version 6.6. The reason for this is that PySide Flatpak base app is only available from the version 6.7 and upwards.

This file reads that we use the markdown module and the build info is provided by the python3-markdown.json manifest file. We are going to create this manifest automatically using flatpak-pip-generator.

Download flatpak-pip-generator, and save it into the simplemdviewer/env/bin/ directory:

#From within the simplemdviewer/ directory
wget https://raw.githubusercontent.com/flatpak/flatpak-builder-tools/master/pip/flatpak-pip-generator --directory-prefix env/bin

The generator has a single dependency to run, requirements-parser. After installing it in the virtual environment, the tool can be run:

python3 -m pip install requirements-parser
python3 env/bin/flatpak-pip-generator markdown

You should see a new python3-markdown.json inside simplemdviewer/ now.

We are using the KDE Runtime, which provides Qt dependencies like QtQuick and KDE frameworks like Kirigami, so you will need the Software Development Kit (Sdk) runtime to build the app locally, and the Platform runtime to run it. More than that, the KDE Runtime is based on the general Freedesktop Runtime, which provides Python. You can read more about runtimes in the Flatpak Runtime Documentation.

Install org.kde.Sdk and org.kde.Platform, version 6.6, from Flathub:

flatpak install org.kde.Platform/x86_64/6.6 org.kde.Sdk/x86_64/6.6

We are using the PyQt Baseapp, which contains an already built and ready-to-use PyQt we can quickly add on top of the KDE Runtime, so we need to install it as well.

For a PyQt Flatpak application, we are using the PyQt Baseapp, which contains an already built and ready-to-use PyQt we can quickly add on top of the KDE Runtime, so we need to install it as well. Alternatively, you can use the PySide Baseapp, which provides a similar ready-to-use PySide6 environment.

flatpak install com.riverbankcomputing.PyQt.BaseApp/x86-64/6.6

To attempt a first build of the flatpak, run:

flatpak-builder --verbose --force-clean flatpak-build-dir org.kde.simplemdviewer.json

Tip You can add the flag `--install-deps-from flathub` to flatpak-builder to make it download the Sdk, Platform and Baseapp for you instead of installing them manually.

If you installed Flathub as a user repository, you will need to add the --user flag to install the runtime. Otherwise you might see the error "Flatpak system operation Deploy not allowed for user".

Test the flatpak build:

flatpak-builder --run flatpak-build-dir org.kde.simplemdviewer.json simplemdviewer

Build a distributable nightly flatpak bundle:

flatpak-builder flatpak-build-dir --repo=simplemdviewer-master --force-clean --ccache org.kde.simplemdviewer.json
flatpak build-bundle simplemdviewer-master simplemdviewer.flatpak org.kde.simplemdviewer

Now we can either distribute the simplemdviewer.flatpak directly to the users, or submit the application to a flatpak repository, like the most popular repository, Flathub. See the App Submission Guidelines.

Other improvements you can make to your application:

  • Signing the source archive with a detached signature.

  • Providing copyright and licensing information for each file with REUSE.

  • Learn more about building flatpak apps with our [Flatpak Tutorial]({{< ref "flatpak" >}}) and the official documentation.

  • Consider making it an official [KDE Application]({{< ref "add-project" >}}), building [Flatpak nightlies using KDE infrastructure]({{< ref "docs/packaging/flatpak/publishing" >}}).

  • Follow the Flathub Quality Guidelines to refine the presentation of your application on Flathub.

Happy hacking.

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