Build Snap packages with Docker

Armhf Snap builder:

Amd64 Snap builder:

Install Docker

Install docker

sudo apt install docker.io
docker pull snapcore/snapcraft
sudo usermod -a -G docker $USER
docker run --rm --privileged multiarch/qemu-user-static:register --reset

Build with snapcraft

Build the two docker images (or skip this step to get them from dockerhub):

docker build -t dawidcrivelli/snacraft_armhf:latest . 
docker build -t dawidcrivelli/snacraft_armhf:latest-amd64 -f Dockerfile.amd64 .

Copy the sources (here supposed to be in the src folder) to a subdirectory, since Snapcraft clutters the working directory:

mkdir -p build/{armhf,amd64}
cp -ru src/ build/armhf
cp -ru src/ build/amd64

Build the proper snaps:

docker run -d --rm -v $PWD/build/armhf:/build dawidcrivelli/snacraft_armhf:latest sh -c "snapcraft clean && snapcraft"
docker run -d --rm -v $PWD/build/amd64:/build dawidcrivelli/snacraft_armhf:latest-amd64 sh -c "snapcraft clean && snapcraft"

Example

We'll clone a Node.js example published on the Snapcraft.io webpage:

git clone git@github.com:didrocks/chuck-norris-webserver.git

It's very easy to cross-build it, in interactive mode to see it succeed:

docker run -it --rm -v $PWD/chuck-norris-webserver:/build snaparm snapcraft

At the end, in the chuck-norris-webserver directory you will find the file chuck-norris-webserver_1.0.0_armhf.snap, confirming that the cross-compilation succeded.