lxcraft

Simplifies building snap files that depend on locally modified snap files.

It builds the snap inside a LXC container using "--destructive-mode", which allows to do it in a safe way. Everything is defined with a YAML file.

Uninstalling old, non-pip versions of LXCraft

If the installer says that it can't uninstall lxcraft because it is a distutils-installed program, you must first manually remove it from the system with the 'uninstall-old.sh' script.

Also, if it was installed locally in your $HOME folder, then you should delete any file or folder that contains 'lxcraft' that is located in your $HOME/.local folder.

Installing LXCraft

Just run at the source folder:

python3 -m pip install .

If you receive an error, ensure that the source folder doesn't have any of these folders:

build
dist
lxcraft.egg-info

If they do exist, delete them and try again. Also, ensure that no old, pre-pip versions are installed, removing them with the 'uninstall-old.sh' script.

BASH completion

If you installed lxcraft without SUDO, you won't have bash completion support. To fix this, just add to your ~/.bashrc file, at the end:

source "$HOME/.local/share/lxcraft/lxcraft.completion"

and any new shell will have completion.

YAML format

This is an example configuration file:

vmname: gtk3test
image: images:ubuntu/jammy

force_debug: False

snaps:
  snapcraft:
    - store
    - channel=5.x
  core22:
    - edge
  gtk-common-themes:
    - store
  /home/raster/workspace/snapcraft/snapcraft*.snap:
    - classic
    - local
  gnome-42-2204-sdk:
    - path: /home/raster/workspace/gnome-sdk/gnome-sdk.snap
    - local

debs:
  - cmake
  - git

• vmname contains the name for the LXC container. If no name is provided, 'lxcraft' plus the current folder will be used (but only the last element; thus, running at /home/user/workspace/aprogram will use 'lxcraft_aprogram' as the name for the LXC container).

• image: the image from which generate the container

• snaps: an optional list with the snaps to install inside the container before building the snap. They can be obtained from the store or from a local file. If it is local, the name can contain wildcards, in which case the most recent file matching the expression will be installed. An important detail is that the order is preserved, so it is possible to specify a local snap to be installed before another from the store that depends on that, thus ensuring that the local will be installed. Each snap can have these elements:

  • store: it means that the snap must be downloaded from the SNAP store. If neither 'local' nor 'store' element is present, it will be presumed that it is 'store', unless a 'path' element is present.

  • local: the snap is located in the local drive, in the specified path

  • classic: the snap requires the --classic parameter to be installed

  • edge: only for 'store' snaps, specifies to install from latest/edge

  • channel=...: allows to specify a channel

  • path: only for local snaps. It specifies the path where the local snap is located. It overrides a path specified in the snap name. If it does exist, it is presumed that the snap is local, even if the 'local' element isn't present. This allows to easily switch between local and remote SNAPs just by commenting the 'path' element.

• debs: contains a list of .deb files to be installed inside the container before building the snap. It is optional.

• force_debug: if it is True, it will pass always the -v parameter to snapcraft.

Using lxcraft

Just create a configuration file called lxcraft.yaml in your project's folder and then run:

lxcraft.py init
lxcraft.py build

It will create the container, install the snaps and .deb files, copy all the files in the current folder into the container, create the snap, and copy it outside the container.

To update the packages inside the container, just use lxcraft.py update. It will do:

apt update
apt dist-upgrade -yy

inside the container, and also will reinstall all the snaps.

To destroy the container, just use lxcraft.py destroy. It can be regenerated with lxcraft.py init again if needed.

You can user lxcraft.py clean to fully remove the working directory inside the container, thus allowing to start from the beginning with snapcraft but without having to destroy and re-recreate the container from scratch.

Also, you can run specific snapcraft commands inside the container with lxcraft.py snapcraft command .... This allows to clean an specific part, or to just execute one part...

Finally, it is possible to run a shell inside the container just with lxcraft.py shell.

You can also pass the -v parameter, which will be added to snapcraft when called.

Accessing the container data

All the files in the project folder are copied inside the container into the /craft_XXXXXXXXX folder at the beginning of the build process, where XXXXXXX is the MD5 hash of the project's name. This is done to ensure that the specific lxcraft folder isn't used in a snapcraft.yaml file, and that only the $CRAFT_XXXXX environment variables are used (in fact, lxcraft will check if the folder appears inside the snapcraft.yaml file, and show an error in that case).

It is also in this folder where the snapcraft folders (like parts, stage or prime) are located, so it is easy to enter inside and check the status of the files after a failed building.

It is possible to include the --copy-data parameter after the shell command, and the current data in the project folder will be copied into the container, like when the project is build.

Activating the build environment

When a shell is launched, lxcraft will check the last .log file for the last build environment used, and will generate a file called /envi.sh with it. If you need to try to build something, just run:

source /envi.sh

and the last build environment will be configured in the shell.

Creating the "contents" snap from the "SDK" snap

Although the SDK snap for Gnome can be built directly using snapcraft, the "contents" one can't, because, by default, it downloads the SDK from the store and uses it to get the libraries and other elements. So after building a custom SDK snap, a custom "contents" snap must be built to.

To do this, just edit the "snapcraft.yaml" file forthe "contents" and change the line:

stage-snaps: [ gnome-42-2204-sdk/latest/edge ]

with:

override-build: |
  craftctl default
  cp -a /snap/gnome-42-2204-sdk/current/usr $CRAFT_PART_INSTALL/
  cp -a /snap/gnome-42-2204-sdk/current/etc $CRAFT_PART_INSTALL/
  cp -a /snap/gnome-42-2204-sdk/current/var $CRAFT_PART_INSTALL/
  cp -a /snap/gnome-42-2204-sdk/current/lib $CRAFT_PART_INSTALL/

and ensure that in the lxcraft.yaml file you are installing the SDK package from the local one.