A snake that can run

ferret provides a new shebang line for your python script that will install dependencies into a fresh venv - saving you the hassle of packaging and distribution. ferret lets you focus on writing just the code you need without sacrificing libraries.

• Install ferret on the target environment:

pip install ferret # Warning: this will work with a python3 venv, but not a virtualenv (as used by pipsi)

• Replace your shebang line with this:

#! /usr/bin/env ferret

• Declare your dependencies in your module's docstring:

"""
A helpful description about your module

ferret:
- requests == 2.18.4
"""

When you run a script with ferret, it parses the file for dependency declarations, and prepares a venv to match. The environments are kept under ~/.local/ferret/venvs (you can safely delete the entire contents of that folder).

Once you've installed ferret, take it for a spin:

cat > just_a_script.py << EOF
#! /usr/bin/env ferret
"""
Gets my IP from icanhazip.com

ferret:
- requests == 2.18.4

"""

import requests

response = requests.get('http://icanhazip.com')
response.raise_for_status()
print(response.text())
EOF
chmod +x just_a_script.py
./just_a_script.py

The first time you run the script, ferret will set up a venv and install requests in it. Subsequent runs will re-use that environment.