If you need Imagick for your WordPress test suite, you might run into a cryptic Exited with code 141 error:
Fortunately, you can ignore this error! Simply append || true to your install statement. In total, your Imagick incantations will look like this:
sudo apt-get update
sudo apt-get install -y libmagickwand-dev --no-install-recommends
yes '' | sudo pecl install imagick || true
sudo docker-php-ext-enable imagickTada!