E: Unable to locate package software-properties-common docker file
You need to add the universe repository:
RUN apt-get update &&
apt-get install -y software-properties-common &&
add-apt-repository universe &&
apt-get install -y php-apcu
If you get a "Error: 'universe' invalid" then you need to use the full source line:
sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe"
instead of "universe" in your apt-add-repository line.