Python Environments
Page Contents
Virtual Environments
References:
- A non-magical introduction to Pip and Virtualenv for Python beginners by Jamie Matthews.
- Pipenv & Virtual Environments, Hitchhier's Guide to Python.
- Python Virtual Environments: A Primer
- Pipenv: Python Dev Workflow for Humans
Note: Recommend PipEnv - superceeds virtualenv - see next secion!
VirtualEnv
# Install
pip install virtualenv
# Create project virtual env for Python 2
cd my_project_folder
virtualenv my_project # virtualenv my_project will create a folder in the current
# directory which will contain everything you need for this
# private environment
# Create for Python 3
python3 -m venv env
# Use the venv
source my_project/bin/activate
# ... Your prompt should become prefixed with your environment name
# ... After activating, a new path to the Python interpretter in your
# ... environment folder takes precedence so it will be used. Same for
# ... the python package path lookup etc...
# Install packages as usual
pip install <package-name>
# When finished...
deactivate
# Delete a venv
rm -fr my_project
# Snapshot of current state:
pip freeze > requirements.txt
# Load snapshot
pip install -r requirements.txt
AutoEnv
You can supplement VirtualEnv with something called AutoEnv. It is a little utility that
will monitor your change-directory commands. When you cd into a directory
that contains a .env file it will try to source that file. So, if inside that
file you have the line source my_project/bin/activate, when you change into
that directory, it will automatically activate your project for you. Happy days!
DirEnv
The author of AutoEnv actually recommends trying this above AutoEnv. TODO.
Pipenv: Python Dev Workflow for Humans
See Pipenv: A Guide to the New Python Packaging Tool.
Pipenv is a tool that aims to bring the best of all packaging worlds (bundler, composer, npm, cargo, yarn, etc.) to the Python world ...
... It automatically creates and manages a virtualenv for your projects, as well as adds/removes packages from your Pipfile as you install/uninstall packages ...
... The problems that Pipenv seeks to solve are multi-faceted:
- You no longer need to use pip and virtualenv separately. They work together.
- Managing a requirements.txt file can be problematic, so Pipenv uses Pipfile and Pipfile.lock to separate abstract dependency declarations from the last tested combination.
- ...
... Pipfiles contain information for the dependencies of the project, and supersedes the requirements.txt file used in most Python projects.
Install using pip3 install pipenv and create a new virtualenv using pipenv --python 3[.minor].
Now, to add packages to your project use pipenv install <package>[~=maj.min[.patch]]
Like the original environments, it needs tobe actived: pipenv shell. Creates virtual environment if one doesn't exist. Note, pipenv creates all virtual environments in a default location.
To push to production, lock your environment: pipenv lock. Creates/updates the Pipfile.lock file (never edit this!).
To install from your lock file use pipenv install --ignore-pipfile.
To leave a pipenv virtual environment just exit the current shell: pipenv starts a new shell session with the virtualenv pathing instead of changing the pathing in the current shell session.