Pipenv Notes

Kourtney Lee included in Develop Environment

2021-09-26 395 words 2 minutes

Contents

Why Pipenv

When maintaining many Python projects,
different projects might use different versions of the same Python libraries.
Not using a virtual environment and installing all Python modules directly on your machine will lead to version conflicts.

In the past, the mechanism of virtualenv + requirements.txt allowed different projects to use different versions of the same package,
and also enabled new developers or production environments to quickly install the packages required by the project.

However, updating packages was quite troublesome,
requiring manual re-exporting of a new requirements.txt.
Furthermore, when a project had different environment requirements (e.g., development environment and production environment),
two sets of package configurations, requirements-prod.txt and requirements-dev.txt, had to be maintained.
Without pyenv, it was also impossible to switch between different Python versions.

Later, the officially recommended pipenv from Python solved these problems,
making it convenient to achieve the following with just commands:

Create independent Python versions and package virtual environments.
Install and record package versions in automatically generated Pipfile and Pipfile.lock, while checking package security through package hash values.
Record package usage environments (separating development and production environments).
Read .env files to set environment variables for the virtual environment.
Automatically switch Python versions in the system (or Python versions installed with pyenv).

Operating Pipenv

Install Pipenv

pip3 install pipenv

Pipenv Commands

Create an independent virtual environment for a specific Python version:
Navigate to the project directory.
```
pipenv --python 3.8
```
- Note that the specified Python version must be available on the system; otherwise, you need to install it using pyenv.
Install packages
```
pipenv install flask
```
Install development packages
Packages with --dev will be placed under [dev-packages] in the automatically generated Pipfile.
```
pipenv install pytest --dev
```
Uninstall packages
```
pipenv uninstall flask
```
Execute scripts in the created virtual environment
```
pipenv run python server.py
```
Other commands like pytest can also be executed.
```
pipenv run pytest
```
Enter the virtual environment
```
pipenv shell
```
To exit the virtual environment, simply type exit.
Create a virtual environment using existing Pipfile and Pipfile.lock
```
pipenv install
```
To install development environment packages as well:
```
pipenv install --dev
```
Create Pipfile and Pipfile.lock from requirements.txt
```
pipenv install
```
Output requirements.txt
This is generally not necessary, but in some special cases (e.g., requirements for specific platforms), it can still be done.
```
pipenv lock --requirements > requirements.txt
```
Upgrade packages in the virtual environment
```
pipenv update
```
Delete the current virtual environment
```
pipenv --rm
```

Upgrade Pipenv

pip3 install --upgrade pipenv