Generate Docker image for the CI on Linux:

osquery-ubuntu18.04-toolchain.dockerfile is the Dockerfile used for this; it's made for a multi-architecture image (x86 and arm64). To create a multi-architecture image we have to use the docker buildx command, a different driver than the one normally used and also emulation by qemu.

Using an Ubuntu 18.04 as the host:

1. Ensure docker is installed with sudo apt install docker-ce
2. Ensure that the docker systemd service is running with sudo systemctl status docker. If not start it with sudo systemctl start docker
3. Check with cat /proc/sys/fs/binfmt_misc/qemu-* that you have interpreter /usr/bin/qemu-aarch64. If nothing is returned, you might have to install/register arm64 emulation via sudo docker run --privileged --rm tonistiigi/binfmt --install arm64
4. Add a new builder instance with

sudo docker buildx create --driver docker-container --name multiarch
sudo docker buildx inspect --bootstrap multiarch

5. Verify that there's no error and that Platforms contains both linux/amd64 and linux/arm64
6. Select the builder to use with sudo docker buildx use multiarch

Now you're ready to build, test and push the image. Use the Makefile in this folder to do so.