Keeping the Ubuntu system-level Python version and modules independent from those desired at each project level is a difficult task best managed by a purpose-built tool.
There are many solutions in the Python ecosystem, but one that stands out for simplicity is pyenv and pyenv-virtualenv.
pyenv allows you to install and switch between different versions of Python, while pyenv-virtualenv provides isolation of pip modules, for independence between projects.
Install pyenv
Because pyenv builds various Python versions directly from source, you first need the Ubuntu OS level apt dependencies.
sudo apt install -y make build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev xz-utils tk-dev libffi-dev liblzma-dev python3-openssl
Then install pyenv using its installation script.
curl https://pyenv.run | bash
Configure Bash settings
To persist the proper shell settings, add the following lines to ~/.bashrc
export PYENV_ROOT="$HOME/.pyenv" [[ -d $PYENV_ROOT/bin ]] && export PATH="$PYENV_ROOT/bin:$PATH" eval "$(pyenv init -)" eval "$(pyenv virtualenv-init -)"
reload with new settings.
exec "$SHELL"
Multiple Python versions with pyenv
Use pyenv to install two different versions of Python.
pyenv install --list | grep 3\.12 # install 2 different versions pyenv install 3.12.0 pyenv install 3.12.1 # set global Python version as default pyenv versions; pyenv global 3.12.1; pyenv versions # validate where python and pip are pointed to which python; which python3 which pip; which pip3 # validate newest version of python and pip are in use python --version; python3 --version pip --version; pip3 --version # make sure we are using latest version of pip globally pip3 install --upgrade pip
Distinct virtualenv for pip module isolation
Use virtualenv to create isolated environments that can be used for specific projects.
# create virtualenv for two different versions of Python pyenv virtualenv 3.12.0 pytest3120 pyenv virtualenv 3.12.1 pytest3121 # list virtualenv available pyenv virtualenvs
Test pip module isolated to pytest3120 virtualenv.
# enter virtualenv
pyenv activate pytest3120
python --version
pip list
pip install python-string-utils
pip list
# test usage of module
python -c "import string_utils; print(string_utils.is_string('hello'))"
# leave virtualenv
pyenv deactivate
Test pip module isolated to pytest3121 virtualenv.
# enter virtualenv
pyenv activate pytest3121
python --version
pip list
pip install simple_env
pip list
# test usage of module
foo=BAR python -c "import simple_env as se; print(se.get('foo'))"
# leave virtualenv
pyenv deactivate
Auto-loading virtualenv
Because of this line added to ~/.bashrc earlier, we also have the ability to auto-activate a virtualenv simply by changing into a python project directory.
eval "$(pyenv virtualenv-init -)"
Here we auto-load the virtualenv named “pytest3120”.
# create python project directory mkdir pytest3120 && cd $_ # set virtualenv to use pyenv local pytest3120 # special file now created, which triggers virtualenv cat .python-version # show local pyenv settings pyenv versions pyenv which python; pyenv which pip python --version ; pip --version # test, should be 3.12.0 version echo -en '#!/usr/bin/env python\nimport sys\nprint(sys.version)' > main.py python main.py cd ..
And here we auto-load the virtualenv named “pytest3121”.
# create python project directory mkdir pytest3121 && cd $_ # set virtualenv to use pyenv local pytest3121 # special file now created, which triggers virtualenv cat .python-version # show local pyenv settings pyenv versions pyenv which python; pyenv which pip python --version ; pip --version # test, should be 3.12.1 version echo -en '#!/usr/bin/env python\nimport sys\nprint(sys.version)' > main.py python main.py cd ..
REFERENCES