Dockerfile to build a specific version of Python and set it as the default using Deadsnakes

gistfile1.txt

####
# Specify the OS you want to run the Docker container in
# For the latest version of Ubuntu, use:
# FROM ubuntu:latest
# Learn more about this Ubuntu image, and versions (tags):
# https://hub.docker.com/_/ubuntu
####
FROM ubuntu:22.04

#####
# Variables to change before building your image
#
# Define the version of Python to install
# For example "3.11" will get the latest version of 3.11 (ex 3.11.4, 3.11.5, etc)
ARG PYVER="3.11"

# Define the username and email you will use for Git
ARG GITUSERNAME="Your Username"
ARG GITEMAIL="your.email@yourdomain.com"
#####

# These settings prevent a timezone prompt when Python installs
# Use this article to find your time zone (TZ):
# https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
ENV TZ=US/Pacific \
    DEBIAN_FRONTEND=noninteractive

# Update the apt repo
RUN apt-get update

# Install Python (software-properties-common), Git, and Python utilities
# Learn about the deadsnakes Personal Package Archives, hosted by Ubuntu: 
# https://www.youtube.com/watch?v=Xe40amojaXE
RUN apt-get install -y software-properties-common && \
    add-apt-repository -y ppa:deadsnakes/ppa && \
    apt-get install -y python$PYVER \
    python3-pip \
    git-all

# Upgrade packages to the latest version
RUN apt-get -y upgrade

# Update PIP (Python's package manager)
RUN python3 -m pip install --upgrade pip

# Configure git
RUN git config --global user.name "$GITUSERNAME" &&\
    git config --global user.email $GITEMAIL &&\
    git config --global init.defaultBranch main

# Set PYVER as the default Python interpreter
RUN update-alternatives --install /usr/bin/python3 python /usr/bin/python$PYVER 1
RUN update-alternatives --set python /usr/bin/python$PYVER
RUN update-alternatives --set python /usr/bin/python$PYVER