When a package's exact name is not known (python3, python38, something scl) file name searches can do a more complete search: yum provides '*bin/python3*'

Correct, there is no python3.8 in EPEL 7. There is a python3.6 in EL 7, and EPEL policy is not to replace EL packages. Plus the distro's policy to avoid major upgrades, would seem like it is stuck on older Python.

Your yum repo list hints that CentOS software collections are enabled, which could be an alternative.

yum install centos-release-scl-rh
yum install rh-python38-python

Note both the package name and the files are prefixed, which allows coexistence with other pythons. While perhaps SCL is not the most popular packaging convention, it is already built and public, an advantage over your own source builds.

Currently CentOS 7 is 87 weeks from end of life, which is not a lot by EL time scales. Most of the maintainer attention is on EL 8 and 9, 7 is critical fixes only.

Budget some of that time to figure out what you are are going to do post CentOS 7. Which may be non-trivial, as CentOS 8 is dead, and if Stream is not what you need, may be switching distros.

Installing from RPM is generally better, because:

• you can install and uninstall (properly) python3.
• the installation time is way faster. If you work in a cloud environment with multiple VMs, compiling python3 on each VMs is not acceptable.

Solution 1: Red Hat & EPEL repositories

Red Hat has added through the EPEL repository:

• Python 3.4 for CentOS 6
• Python 3.6 for CentOS 7

[EPEL] How to install Python 3.4 on CentOS 6

sudo yum install -y epel-release
sudo yum install -y python34

# Install pip3
sudo yum install -y python34-setuptools  # install easy_install-3.4
sudo easy_install-3.4 pip

You can create your virtualenv using pyvenv:

pyvenv /tmp/foo

[EPEL] How to install Python 3.6 on CentOS 7

With CentOS7, pip3.6 is provided as a package :)

sudo yum install -y epel-release
sudo yum install -y python36 python36-pip

You can create your virtualenv using pyvenv:

python3.6 -m venv /tmp/foo

If you use the pyvenv script, you'll get a WARNING:

$ pyvenv-3.6 /tmp/foo
WARNING: the pyenv script is deprecated in favour of `python3.6 -m venv`

Solution 2: IUS Community repositories

The IUS Community provides some up-to-date packages for RHEL & CentOS. The guys behind are from Rackspace, so I think that they are quite trustworthy...

https://ius.io/

Check the right repo for you here:

https://ius.io/setup

[IUS] How to install Python 3.6 on CentOS 6

sudo yum install -y https://repo.ius.io/ius-release-el6.rpm
sudo yum install -y python36u python36u-pip

You can create your virtualenv using pyvenv:

python3.6 -m venv /tmp/foo

[IUS] How to install Python 3.6 on CentOS 7

sudo yum install -y https://repo.ius.io/ius-release-el7.rpm
sudo yum install -y python36u python36u-pip

You can create your virtualenv using pyvenv:

python3.6 -m venv /tmp/foo

As per the instructions on How to Install Python 3.8 on Ubuntu, Debian and LinuxMint – TecAdmin, try the following:

Prerequisites:

Install [and or update] the following packages; build-essential, checkinstall, libreadline-gplv2-dev, libncursesw5-dev, libssl-dev, libsqlite3-dev, tk-dev, libgdbm-dev, libc6-dev, libbz2-dev, libffi-dev, zlib1g-dev.

sudo apt install build-essential checkinstall
sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev libffi-dev zlib1g-dev

Thereafter, change directory (cd) to your opt folder [or any convenient folder] and download the python source code from python's server:

First change directory (cd) to the 'opt' folder:

cd /opt/

Download the source code

sudo wget https://www.python.org/ftp/python/3.8.3/Python-3.8.3.tgz

Extract the [downloaded] source code files

sudo tar xzf Python-3.8.3.tgz

Change directory (cd) the Python Folder [created after the extraction]

cd Python-3.8.3

Compile the source code

sudo ./configure --enable-optimizations

then

sudo make altinstall

Once the compilation is completed, you can confirm that Python 3.8 has been installed successfully with:

python3.8 -V

You should see the response Python-3.8.3.

However, to precisely answer your question, python 3.8 isn't available via ubuntu official repos. You would have to add a PPA to get python 3.8 using sudo apt install [python3.x.x].

The process is described on How to Install Python 3.8 on Ubuntu 18.04 | Linuxize

Hope this helps and I hope I answered your question adequately.

ppa:deadsnakes was decommissioned for Ubuntu 16.04 (Xenial Xerus). Try to build a custom .deb package.

You have to enable the EPEL repo, use:

yum --enablerepo=extras install epel-release

This command will install the correct EPEL repository for the CentOS version you are running.

After this you will be able to install python-pip.