[Python](EN) Run pyenv-virtualenv python in crontab

Add python file which runs in pyenv-virtualenv to crontab and run it.

Environment and Prerequisite

• Linux
• pyenv
• pyenv-virtualenv

Post Background

Background

• To isolate dependency in python versions, people use pyenv and pyenv-virtualenv. By using those softwares we can make virtual environment which can run python code file. I encounter run python code file in crontab which runs in virtual environment.
• It can be used in not only crontab but also systemd’s service and shell script.

Prior knowledge

Python Module and Path

• When running python code file, there are many important things to care. However this post focus on python module path and which python you use.

sys.path

• sys.path: A list of strings that specifies the search path for modules.
• Refer sys.path when load python module using import.

>>> import sys
>>> sys.path
['', '/home/twpower/.pyenv/versions/3.6.2/lib/python36.zip', '/home/twpower/.pyenv/versions/3.6.2/lib/python3.6', '/home/twpower/.pyenv/versions/3.6.2/lib/python3.6/lib-dynload', '/home/twpower/.pyenv/versions/jupyter-notebook/lib/python3.6/site-packages']

pyenv versions

• Show number of python versions which installed by pyenv
• Also includes pyenv-virtualenv’s virtual environment.

$ pyenv versions
* system (set by /home/twpower/.pyenv/version)
  3.5.2
  3.5.3
  3.6.1
  3.6.2
  3.6.2/envs/jupyter-notebook
  3.6.2/envs/test
  jupyter-notebook
  test

pyenv path

• pyenv versions python and modules are located in $(pyenv root)/versions path.

$ ls /home/twpower/.pyenv/versions/
3.5.2  3.5.3  3.6.1  3.6.2  jupyter-notebook  test

How To Apply

Method1 - Use virtual environment’s python directly

• Each pyenv-virtualenv has its own python. So its python path is different and also sys.path is different.
• Use python code file directly which is in pyenv-virtualenv.
• Path: [pyenv root]/versions/[virtualenv name]/bin/[python version]

crontab

30 20 * * * /home/twpower/.pyenv/versions/jupyter-notebook/bin/python3.6 /home/twpower/test.py

Method2 - Use “pyenv activate” in script

• Add pyenv activate to make virtual environment in shell script and run python code.

test.sh

#!/bin/bash

source /home/twpower/.bash_profile
source /home/twpower/.bashrc

pyenv activate jupyter-notebook
python /home/twpower/test.py

crontab

30 20 * * * /home/twpower/test.sh

Reference

• https://docs.python.org/3/library/sys.html#sys.path
• https://github.com/pyenv/pyenv#locating-the-python-installation