How to Install Python 3.6.* in Ubuntu 16.04 LTS - Docker

python_ubuntu_docker.sh

sudo apt-get install software-properties-common

sudo add-apt-repository ppa:jonathonf/python-3.6
sudo apt-get update
sudo apt-get install python3.6 libpython3.6

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 2
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 1

sudo rm /usr/bin/python3
sudo ln -s python3.6 /usr/bin/python3

#ref
#http://ubuntuhandbook.org/index.php/2017/07/install-python-3-6-1-in-ubuntu-16-04-lts/

Cool!
Did it work for you without adding -y to apt-get installs?

In a dockerfile you don't require the sudo calls and I also required -y in front of the install packages. Make sure to also run apt-get update before the first line.