The image is available on docker hub.
To use the docker image, do a docker pull, then you can call the CLI as part of the docker run command.
Note that to see your sketch, the working directory must be mounted in the image.
docker pull bluetoothkeyboard/arduino-cli
docker run -it --mount src=${PWD},target=/mnt,type=bind bluetoothkeyboard/arduino-cli:latest arduino-cli
docker build .