jQrgen/snapcraft-container

Multi-architecture Snapcraft container image with support for Systemd

These container images start systemd and execute the command line passed on invokation. The commandline is executed as an interactive systemd service unit.

IMPORTANT These container images are NOT compatible with Docker provided through the Snap Store due to confinement rules applied to the dockerd interfering with (preventing) our container's execution.

You may override the entrypoint with the --entrypoint parameter if you need to run the container without starting systemd. Or you may drop to a shell with systemd running by setting the command to bash.

These container images require you to pass --privileged.

Notes

For builds against core the version of Systemd included in Ubuntu Xenial, and thus included in the core container images, is not compatible with cgroups version 2. This causes the core container image to fail to finish starting on newer distros. On systems that use cgroups2 you might still be able to run the core container images by adding --tmpfs /sys/fs/cgroup to the docker or podman command line.

Previous instructions, based on earlier iterations of the container images, required you to create and use an AppArmor namespace - this is not necessary any more. That is, you no-longer need to create a separate AppArmor namespace directory at /sys/kernel/security/apparmor/policy/namespaces/docker-snapcraft and you can drop the --security-opt apparmor=":docker-snapcraft:unconfined" parameter from your docker command line.

Running snapcraft

Running without specifying a command will run snapcraft without any parameters:

docker run --rm -it --privileged -v $PWD:/data -w /data diddledani/snapcraft:core22

To run with parameters, specify snapcraft [...params] when creating the container:

docker run --rm -it --privileged -v $PWD:/data -w /data diddledani/snapcraft:core22 snapcraft stage --enable-experimental-package-repositories

Drop to a shell with systemd running

docker run --rm -it --privileged -v $PWD:/data -w /data diddledani/snapcraft:core22 bash

Drop to a shell without starting systemd

docker run --rm -it --privileged -v $PWD:/data -w /data --entrypoint bash diddledani/snapcraft:core22

Experimental support for running through Podman

These containers should now be compatible with Podman, but have yet to receive much in the way of testing and validation. With the proviso that this is highly experimental for these images, you can try to run the build through Podman with:

sudo podman run --rm -it --privileged --systemd always -v $PWD:/data -w /data docker.io/diddledani/snapcraft:core22

Running through sudo seems to be a requirement to allow mounting squashfs filesystems, and we still need --privileged the same as when we are running through Docker. We also need to add the --systemd always flag to get Podman to set up the runtime environment appropriately for running Systemd inside the new container instance.