gimp/build/linux/flatpak

GIMP Flatpak HowTo

Stable and Development releases

The Flathub repository hosts our stable and development point releases: https://github.com/flathub/org.gimp.GIMP

We recommend to look at the README.md file in respectively the master or beta branches of this repository to know more about release procedures.

Nightly builds

Flathub does not host nightly builds, therefore we publish them on GNOME's Nightly repository. Our "nightlies" are actually "weeklies" through a Gitlab job schedule named "Flatpak nightly", which builds whatever is on GIMP's repository master branch. The nightly manifest file is: build/linux/flatpak/org.gimp.GIMP-nightly.json

This file should remain as close as possible to the development manifest (org.gimp.GIMP.json file on the beta branch of the Flathub repository) which itself should remain as close as possible to the stable manifest (org.gimp.GIMP.json file on the master branch of the Flathub repository), since the nightly manifest is meant to become beta eventually, which itself is meant to become stable eventually.

Base rule to update the nightly build manifest:

• Regularly org.gimp.GIMP-nightly.json should be diffed and synced with development and stable org.gimp.GIMP.json, in particular for all the dependencies (which are mostly the same across all 3 builds).
• A merge request with the label 5. Flatpak package will contain the *flatpak* jobs, hence allowing theoretically to build a standalone .flatpak (without being published to the nightly repository) for MR code be tested.

Maintaining the modules

• GIMP uses Flatpak's GNOME runtime, which contains a base of libraries, some of which are dependencies of GIMP. While both the stable and development versions should use the latest stable runtime version, the nightly manifest uses the master version, which is more of a rolling release.

• Other GIMP dependencies which are not available in the GNOME runtime should be built along as modules within GIMP's flatpak. Check format in org.gimp.GIMP-nightly.json and add modules if necessary. For more options, check flatpak builder's manifest format.

• Among the dependencies we self-build, some sources on GIMP manifest have set a x-checker-data property which makes it possible to check for updates using flatpak-external-data-checker. To run the tool either install it locally, via flatpak or via OCI image.

  The OCI image is not straightforward at first but is the least intrusive if you already have docker or podman installed:

cd <path-to-gimp-repo>/flatpak/build
podman run --rm --privileged -v "$(pwd):/run/host:rw" ghcr.io/flathub/flatpak-external-data-checker:latest /run/host/org.gimp.GIMP-nightly.json

Our prefered backend for the checker is Anitya, a database maintained by the Fedora project. To set up a new dependency check by Anitya:

1. verify it is available in the database: https://release-monitoring.org/
2. then copy the project ID which is the number in the project URI within the database.
3. Finally add a "x-checker-data" field within the "source" dictionary in the manifest with type "anitya", the "project-id" and a "url-template".
4. We usually want to depend on stable releases only, i.e. set "stable-only to true. On exceptional cases, for very valid reasons only, we might bypass this limitation, adding a comment explaining why we use an unstable release.

• On the other hand, if we increased the runtime version in particular (or when the master runtime evolves), some modules may no longer be necessary and can be removed from our manifest.

  After all, a flatpak is a layered set of modules. Our GIMP build in particular is built over the GNOME runtime, itself built over the Freedesktop runtime, itself based on a yocto-built image. Other than by trial and error, you can find the installed dependencies by running:

flatpak run --devel --command=bash org.gnome.Sdk//master

Inside the flatpak sandbox, GNOME and Freedesktop's module lists (generated manifest as the SDK is built from BuildStream) can be read with::

less /usr/manifest.json

Versioning the flatpaks

• For the development releases and nightly builds, we added the desktop-file-name-prefix property. For a stable release, the property line can be removed from the manifest.

• For a stable release, set top "branch":"stable", and inside the "gimp", "babl" and "gegl" modules, set "tag" to the git tag (ex: GIMP_2_10_34) and "commit" to the git commit hash for this tag.

• For a development release, set top "branch":"beta", and inside the "gimp", "babl" and "gegl" modules, set "tag" to the git tag (ex: GIMP_2_99_14) and "commit" to the git commit hash for this tag.

• For a nightly build, set top "branch":"master", and inside the "gimp", "babl" and "gegl" modules, set "branch" to "master", and remove any "commit" line.