Create snap package

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Snap is a containerized package format which allows the distribution of programs to all Linux distributions. A snap is in a container and has only explicitly defined access to the "outside world", e.g. some libraries of the system or the user's home directory.

Create snapcraft.yaml

  • Install snapcraft to your Ubuntu machine with sudo apt install snapcraft
  • Create snap subdirectory in your project
  • Execute snapcraft init to create snap/snapcraft.yaml initial file
  • See Snapcraft.yaml reference for full list of supported properties.
  • Adapt the file so that it contains all necessary instructions for building the Lazarus program snap.

Example files

Qt5

The kde-neon extension and some tricks will help you to reduce the size of the Snap package to almost the normal binary size. The only thing to keep in mind is that Qt5 needs the libqt5pas-library. In a snapcraft forum post, we were figuring out how to create a small Lazarus Qt5 snap with all needed libraries included. You can find an example at the Cantara project on Github or check the instruction below. 

name: myapp
version: 'version'
summary: any summary
description: |
  Any description
confinement: strict
icon: path-to-logo.png
base: core20
grade: stable

architectures:
  - build-on: amd64

parts:
  myapp:
    plugin: nil
    source: .
    source-type: local
    build-packages:
    - fpc
    - lazarus
    - lcl
    - lcl-utils
    - build-essential
    - libqt5pas-dev
    stage-packages:
    - libqt5pas1
    - libxinerama1
    override-build: |  
      lazbuild -B --ws=qt5 myapp.lpi 
      # Here you have to install (or copy) all the files of your project which you would like to distribute to $SNAPCRAFT_PART_INSTALL/ e.g. the compiled binary, icons and language files
      cp -r languages $SNAPCRAFT_PART_INSTALL/
      install myapp $SNAPCRAFT_PART_INSTALL/
      install myapp.desktop $SNAPCRAFT_PART_INSTALL/
      install myapp.ico $SNAPCRAFT_PART_INSTALL/
      install myapp.png $SNAPCRAFT_PART_INSTALL/
    stage: 
    - lib
    - usr
    - etc
    # make sure that you stage the files and folders to which you have installed (copied) above!
    - myapp
    - languages
    - myapp.desktop
    - myapp.ico
    - myapp.png
  cleanup: # this will make your snap small but keeps the needed libraries
    after: [myapp]
    plugin: nil
    build-snaps: [kde-frameworks-5-91-qt-5-15-3-core20]
    override-prime: |
      set -eux
      for snap in "kde-frameworks-5-91-qt-5-15-3-core20"; do  # List all content-snaps you're using here
        cd "/snap/$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:
  myapp:
    extensions:
      - kde-neon # Don't remove this extension for it provides access to Qt5!
    command: myapp # to change: the command on which the app gets started
    desktop: myapp.desktop # to change: the path to the desktop file which will be used to create the entry in the start menu etc.
    plugs:
    - home
    - network
    - network-bind

GTK2

name: myapp
version: '1.0.0'
summary: Short description of the package.
description: |
  Some more detailed multi-line description.
confinement: strict
base: core20
grade: stable

parts:
  myapp:
    plugin: nil
    source: .
    source-type: local
    build-packages: 
    - fpc
    - lazarus
    - lcl
    - lcl-utils
    stage-packages:
    # Autodetected dependencies
    - libatk1.0-0
    - libcairo2
    - libdatrie1
    - libfontconfig1
    - libfreetype6
    - libfribidi0
    - libgdk-pixbuf2.0-0
    - libgraphite2-3
    - libgtk2.0-0
    - libharfbuzz0b
    - libpango-1.0-0
    - libpangocairo-1.0-0
    - libpangoft2-1.0-0
    - libpixman-1-0
    - libpng16-16
    - libthai0
    - libx11-6
    - libxau6
    - libxcb-render0
    - libxcb-shm0
    - libxcb1
    - libxcomposite1
    - libxcursor1
    - libxdamage1
    - libxdmcp6
    - libxext6
    - libxfixes3
    - libxi6
    - libxinerama1
    - libxrandr2
    - libxrender1
    override-build: |
      lazbuild --build-mode=Release myapp.lpi
      install -d -m 755 $SNAPCRAFT_PART_INSTALL/usr/bin
      install -s -m 755 myapp $SNAPCRAFT_PART_INSTALL/usr/bin/myapp
      install -d -m 755 $SNAPCRAFT_PART_INSTALL/usr/share/applications
      install -m 755 myapp.desktop $SNAPCRAFT_PART_INSTALL/usr/share/applications
    stage:
    - etc
    - lib
    - usr
    - usr/bin
    - usr/share/myapp
    - usr/share/applications/myapp.desktop

apps:
  myapp:
    command: usr/bin/myapp/myapp
    desktop: usr/share/applications/myapp.desktop
    plugs:
    - home
    - desktop
    - x11

Build Snap

  • Build snap using snapcraft command
  • Install newly created snap with:
sudo snap install --dangerous myapp_1.0.0_amd64.snap

Publish your package in Snap Store

snapcraft register
snapcraft login
snapcraft upload myapp.snap
snapcraft release myapp 1 stable

Now your snap should be released and available on snapcraft.io store.

Debug snap

To get to console of snap virtual filesystem use: 

snap run --shell myapp
cd $SNAP

Type exit to leave snap environment. See Debugging snaps for more information.

Use newer Lazarus version

Normally you can use Lazarus IDE version provided by current base (2.0.6 for core20). To use latest stable version with new features you can add following part into your snapcraft.yaml file. This part should be executed before myapp part. You need to update fixed URL based on required Lazarus version. Then those packages will be downloaded and installed before build. 

parts:
  lazarus:
    plugin: nil
    source: .
    source-type: local
    build-packages: 
    - wget
    - libgtk2.0-dev
    override-build: |
      wget -nc https://downloads.sourceforge.net/project/lazarus/Lazarus%20Linux%20amd64%20DEB/Lazarus%203.4/lazarus-project_3.4.0-0_amd64.deb
      wget -nc https://downloads.sourceforge.net/project/lazarus/Lazarus%20Linux%20amd64%20DEB/Lazarus%203.4/fpc-laz_3.2.2-210709_amd64.deb
      wget -nc https://downloads.sourceforge.net/project/lazarus/Lazarus%20Linux%20amd64%20DEB/Lazarus%203.4/fpc-src_3.2.2-210709_amd64.deb
      apt install ./lazarus-project_3.4.0-0_amd64.deb ./fpc-laz_3.2.2-210709_amd64.deb ./fpc-src_3.2.2-210709_amd64.deb
    prime: [-*]
  myapp:
    after: [lazarus]

And remove normal Lazarus build-packages from your app so they are not installed for build: 

  myapp:
    build-packages: 
    - fpc
    - lazarus
    - lcl
    - lcl-utils

GTK2 theme support

There is no snapcraft extension available for GTK2 similarly to GTK3. So GTK2 theming needs to be configured with additional lines.

Content plugs only

To support GTK2 themes used by host system the app needs to have access to GTK2 themes. Standard GTK2 themes can be made available by using content plugs. Those content plugs are external shared packages so they won't make snap bigger. But the application can still print some errors into console.

Extend your snapcraft.yaml file with the following: 

# Additional plugs to pick up the GTK theme and icons from the system
plugs: 
  icon-themes:
    interface: content
    target: $SNAP/data-dir/icons
    default-provider: gtk-common-themes
  sound-themes:
    interface: content
    target: $SNAP/data-dir/sounds
    default-provider: gtk-common-themes
  gtk-2-engines:
    interface: content
    target: $SNAP/lib/gtk-2.0
    default-provider: gtk2-common-themes:gtk-2-engines
  gtk-2-themes:
    interface: content
    target: $SNAP/usr/share/themes
    default-provider: gtk2-common-themes:gtk-2-themes

layout:
  /usr/share/themes:
    bind: $SNAP/usr/share/themes
  /usr/lib/$SNAPCRAFT_ARCH_TRIPLET/gtk-2.0:
    bind: $SNAP/lib/gtk-2.0

Full support

To fully support GTK2 environment we need to use snapcraft desktop helper and include various standard packages. Those packages make snap bigger by ~26 MB so there is a trade-off between size of snap packages and supported features.

Extend your snapcraft.yaml file with the following: 

parts:
  desktop-gtk2:
    source: https://github.com/ubuntu/snapcraft-desktop-helpers.git
    source-subdir: gtk
    plugin: make
    make-parameters: ["FLAVOR=gtk2"]
    build-packages:
    - build-essential
    - libgtk2.0-dev
    stage-packages:
    - libxkbcommon0  # XKB_CONFIG_ROOT
    - ttf-ubuntu-font-family
    - dmz-cursor-theme
    - light-themes
    - adwaita-icon-theme
    - gnome-themes-standard
    - shared-mime-info
    - libgtk2.0-0
    - libgdk-pixbuf2.0-0
    - libglib2.0-bin
    - libgtk2.0-bin
    - unity-gtk2-module
    - locales-all
    - libappindicator1
    - xdg-user-dirs
    - ibus-gtk
    - libibus-1.0-5
  myapp:
    after:
    - desktop-gtk2

# Additional plugs to pick up the GTK theme and icons from the system
plugs: 
  icon-themes:
    interface: content
    target: $SNAP/data-dir/icons
    default-provider: gtk-common-themes
  sound-themes:
    interface: content
    target: $SNAP/data-dir/sounds
    default-provider: gtk-common-themes
  gtk-2-engines:
    interface: content
    target: $SNAP/lib/gtk-2.0
    default-provider: gtk2-common-themes:gtk-2-engines
  gtk-2-themes:
    interface: content
    target: $SNAP/usr/share/themes
    default-provider: gtk2-common-themes:gtk-2-themes

environment:
  XDG_DATA_DIRS: $SNAP/usr/share:$XDG_DATA_DIRS
  GTK_PATH: $SNAP/lib/gtk-2.0

apps:
  myapp:
    command: usr/bin/myapp
    command-chain:
    - bin/desktop-launch

Sound support

Snap supports sound through audio-playback plug. 

apps:
  myapp:
    plugs:
    - audio-playback

You can play wav and mp3 files from command line using play command. See Play Sound Multiplatform. Then you also need to add additional stage-packages to myapp part and setup sox player for pulseaudio: 

parts:
  myapp:
    stage-packages:    
    - sox
    - libsox-fmt-mp3
    - libsox-fmt-pulse
    - libpulse0 

environment:
  LD_LIBRARY_PATH: $SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/pulseaudio
  PULSE_SERVER: unix:/run/user/1000/pulse/native

layout:
  /usr/lib/$SNAPCRAFT_ARCH_TRIPLET/sox:
    bind: $SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/sox

OpenGL support

To support 3D acceleration it is required to use OpenGL plug, package related libraries and set correct path for drivers. 

parts:
  myapp:
    stage-packages:    
    - libglu1-mesa
    - libgl1-mesa-dri

apps:
  myapp:
    plugs:
    - opengl

environment:
  LIBGL_DRIVERS_PATH: $SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/dri

SDL support

Add needed build and stage packages. 

parts:
  myapp:
    build-packages: 
    - libsdl2-dev
    - libsdl2-mixer-dev
    - libsdl2-image-dev
    stage-packages:
    - libsdl2-2.0-0
    - libsdl2-image-2.0-0
    - libsdl2-mixer-2.0-0

snapcraft.yaml file in non-standard subdirectory

Snapcraft normally expect snapcraft.yaml file in snap directory. If your project has packaging for multiple other packaging formats, then you need to use build workaround script. Such shell script can put into directory like myapp/install/snap/local as build.sh file. 

#!/bin/bash
ln -s install/snap ../../../snap
pushd ../../..
snapcraft
popd
rm ../../../snap

Register app in snap store

Setup build on Launchpad

Snap packages can be built automatically on Launchpad. Open Create snap package link form your application branch page.

See also

External links

Retrieved from "https://wiki.freepascal.org/index.php?title=Create_snap_package&oldid=160186"