How to package a plugin that will work on Snap

Configuring the ‘content’ snap manifest

The Snap package that we will create is a content producer snap (being gimp the content consumer snap through gimp-plugins plug), which should have the following snapcraft.yaml in the root folder:

name: PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES
title: PLUG-IN-NAME
summary: PLUG-IN-NAME GIMP Plugin
description: PLUG-IN-DESC
website: PLUG-IN-REPO-URL
license: PLUG-IN-LICENSE
version: PLUG-IN-RELEASE-VERSION
grade: stable
base: SDK-VERSION
compression: lzo
confinement: strict

platforms:
  arm64:
  amd64:

slots:
  gimp-plugins:
    interface: content
    content: gimp-plugins-MAJOR
    source:
      read:
        - $SNAP/PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES.conf
        - $SNAP/PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES

apps:
  dummy-PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES:
    command: "PATH_TO_PLUG-IN"
    extensions: [gnome]

parts:
  add-ld-library-path:
    plugin: dump
    source: PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES.conf/
    organize:
      add-ld-library-path: PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES.conf/add-ld-library-path

  PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES:
    organize:
      usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR: PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES/libs
    build-snaps:
      - gimp
    etc...

Change MAJOR to the GIMP API version your plugin supports, which should correspond to the same plugs:gimp-plugins:content: on GIMP snap manifest. SDK-VERSION should correspond to core:. Then, set the PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES and other metadata accordingly, and configure the parts: section following your build needs.

Creating the add-ld-library-path file

The only asset needed by an content producer snap is the add-ld-library-path file. This is a conventional file that works similarly to Flatpak’s “add-extensions”.“add-ld-path” but on the plug-in side.

So, create a folder named PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES.conf in the same dir as the snapcraft.yaml file and put the add-ld-library-path file there. It should contain the following line:

PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES/libs

Packaging the .snap

Continuing, in the manifest folder, build and package the plug-in this way:

sudo snapcraft pack --destructive-mode --verbosity=verbose

Note that we chose --destructive-mode for convenience. Remove it if you are not running on an Ubuntu-based distro with the target SDK-VERSION.

Now, if necessary, test the package installing it:

sudo snap install --dangerous PLUG-IN-NAME-WITHOUT-SYMBOLS-OR-SPACES*_$(dpkg --print-architecture).snap

Distributing with Snap Store

Typically, your plugin may continue to get new features and bug fixes. And the easiest way to ensure this for the users is to distribute it on Snap Store, the same repository that distributes GIMP Snap.

Take a look at the Snap submission guidelines and, to save your time in the future, we recommend mimic the GIMP Snap distribution script.