I have a Lazarus/Free Pascal project called Cantara which uses Qt5. I finally managed to snap it with this snapcraft.yaml which I placed into the Github repository.
The building works fine and I even managed to give my app a native look and feel with including the following stage-packages:
However, I still struggle with the size of the snap. It is more than 100 MB – compared to classical packages like .deb which are all less then 10 MB. Due to the fact that Qt5 is installed on most Linux distributions, I am wondering whether I can reduce the size of my Snap while allowing it to access parts of the system (e.g. the Qt themes etc.) – or if it is just something I have to deal with when using a containerized package system.
Well, as long as you’re using the kde-neon extension, your snap does not need to include Qt stage-packages. Looking at your snap in edge, you’re shipping Qt libraries (that are most likely all included in the KDE content snap), libLLVM, and tons of icons (e.g. Breeze is included in the content snap, some are included from the gtk-common-themes snap). That means you can probably get rid of a good chunk of your snap size.
Thanks for your fast reply! Actually I have tried before to build the snap without the Qt libraries and style packages: It resulted in errors when starting the snap and if the snap started, it looked not native (very old default design). Maybe I am doing something wrong with the stage part?
What is the content snap and how should I include it?
The cleanup part is something which I had tried before – all resulting in errors as well due to libraries which weren’t found after startup. In addition, I don’t use a snap like kde-frameworks-5-91-qt-5-15-3-core20 where I could do some cleanup…
Actually, you do. Due to your usage of the kde-neon extension, this gets added to your snapcraft.yaml. You can check by doing snapcraft expand-extensions:
The Qt app should look decent with the kde-neon extension; not perfectly integrated into a Gtk desktop environment, but okay. Have you looked at other Qt/KDE apps, e.g. kdenlive or FreeCAD? Do they look bad to you, too?
Thanks for the explanations! Does that mean that I have to stage the directories kf5, data-dir/icons and data-dir/sounds as well in order to really make use of the kde-neon extension?
No, those get mounted into your snap from the content snap at runtime. Because of that, you do not need to ship them and every snap that uses those content snaps can share those resources, which means there’s less to download and better performance.
Also, you shouldn’t usually stage dev packages; they are meant for the building stage.
Just as a very quick & dirty experiment, this version of your packaging gives me a 7 MB snap instead of your 284 MB package:
name: cantara
version: '2.2.3'
summary: A Song Presentation Software.
description: |
A simple, leightweight but powerful program for song presentation in churches, small groups or at karaoke parties.
confinement: strict
icon: Cantara.png
base: core20
grade: stable
architectures:
- build-on: amd64
parts:
cantara:
plugin: nil
source: .
source-type: local
build-packages:
- fpc
- lazarus
- lcl
- lcl-utils
- build-essential
- libqt5pas-dev
stage-packages:
- libqt5pas1
- libatk1.0-0
- libgtk2.0-0
- libxinerama1
override-build: |
lazbuild -B Cantara.lpi --ws=qt5
cp -r languages $SNAPCRAFT_PART_INSTALL/
install cantara $SNAPCRAFT_PART_INSTALL/
install cantara.desktop $SNAPCRAFT_PART_INSTALL/
install Cantara.ico $SNAPCRAFT_PART_INSTALL/
install Cantara.png $SNAPCRAFT_PART_INSTALL/
stage:
- lib
- usr
- etc
- cantara
- languages
- cantara.desktop
- Cantara.ico
- Cantara.png
cleanup:
after: [cantara]
plugin: nil
build-snaps: [kde-frameworks-5-91-qt-5-15-3-core20]
override-prime: |
set -eux
for snap in "kde-frameworks-5-91-qt-5-15-3-core20"; do # List all content-snaps you're using here
cd "/snap/$snap/current" && find . -type f,l -exec rm -f "$SNAPCRAFT_PRIME/{}" "$SNAPCRAFT_PRIME/usr/{}" \;
done
for cruft in bug lintian man icons; do
rm -rf $SNAPCRAFT_PRIME/usr/share/$cruft
done
find $SNAPCRAFT_PRIME/usr/share/doc/ -type f -not -name 'copyright' -delete
find $SNAPCRAFT_PRIME/usr/share -type d -empty -delete
find $SNAPCRAFT_PRIME/usr/lib -type f,l -name 'libQt*.so*' ! -name 'libQt5Pas*.so*' -delete
apps:
cantara:
extensions:
- kde-neon
command: cantara
desktop: cantara.desktop
plugs:
- home
- network
- network-bind
It launches and looks okayish. Maybe some spacing issues here & there. You could try setting QT_STYLE_OVERRIDE to one of the other themes available in the content snap to see if that looks better.
After trying out your snapcraft.yaml on Ubuntu and Arch, I can confirm that it works well and also the design issues are not there anymore. Thank you again for the quick and professional help!
