Help:Toolforge/Python

Python is one of the most used programming languages on Toolforge.

If you don't have a special python setup or want to use the latest versions, you can try using the build service, for which there's several tutorials available.

For guidance on writing tools in Python, see e. g. Help:Toolforge/My first Flask OAuth tool, Help:Toolforge/My first Django OAuth tool and the build service based tutorials.

For this tutorial, we will be using prebuilt container images, the newest Python available on them is python3.11.

Virtual environments with prebuilt images

When using a prebuilt image (such as python3.11) with a webservice or a job, a Python virtual environment (venv) allows the maintainers of a tool to install Python packages using pip without affecting any other tools running in Toolforge. A venv is similar to the use of composer to install PHP libraries or bundler to install ruby libraries that are local to directory rather than system wide.

A virtual environment must be created in the same execution environment that the venv will be used from. This means that any virtual enviroments must be bootstrapped inside a container using toolforge webservice python3.11 shell or a job.

Web services

See Toolforge webservices with Python.

Jobs

Follow these instructions if you are using the Toolforge Jobs framework.

You will need to run a one-time manual job to bootstrap a python venv from inside a job container. This is similar to the instructions about using toolforge webservice python3.11 shell when bootstrapping kubernetes webservices.

Create a script similar to this to create the venv:

$HOME/bootstrap_venv.sh

#!/bin/bash

# use bash strict mode
set -euo pipefail

# delete the venv, if it already exists
rm -rf pyvenv

# create the venv
python3 -m venv pyvenv

# activate it
source pyvenv/bin/activate

# upgrade pip inside the venv and add support for the wheel package format
pip install -U pip wheel

# Change the following section depending on what your tool needs!

# install some concrete packages
# pip install requests
# pip install pyyaml

# or, install all packages from src/requirements.txt
# pip install -r src/requirements.txt

Run the bootstrapping script in the desired python container:

tools.mytool@tools-sgebastion-11:~$ ls bootstrap_venv.sh
bootstrap_venv.sh
tools.mytool@tools-sgebastion-11:~$ chmod ug+x bootstrap_venv.sh
tools.mytool@tools-sgebastion-11:~$ toolforge jobs run bootstrap-venv --command "cd $PWD && ./bootstrap_venv.sh" --image python3.11 --wait
tools.mytool@tools-sgebastion-11:~$ ls pyvenv
pyvenv

Once the venv had been created, you can run your python job as many times as needed as a manual, continuous, or periodic job:

tools.mytool@tools-sgebastion-11:~$ cat src/mytool.py
import requests
r = requests.get('https://www.wikidata.org/wiki/Q1')
print(r.status_code)
tools.mytool@tools-sgebastion-11:~$ toolforge jobs run mytool --command "pyvenv/bin/python src/mytool.py" --image python3.11
tools.mytool@tools-sgebastion-11:~$ cat mytool.out
200

Or, if you're using a shell script as the entry point for your job, use source pyvenv/bin/activate before running any other commands.

For scheduling recurring or continuous jobs, see Help:Toolforge/Jobs framework.

Deprecating Python 2

Many legacy tools and code examples use Python 2.x as a runtime. Use of Python 3.x is encouraged for new code as Python 2.7 stopped being maintained in 2020. Toolforge will provide some amount of support for Python 2.x through 2022 because Debian will be supporting Python 2.7 in Debian 10 (buster). This support will only extend to critical security patches however.

Elasticsearch

See Help:Toolforge/Elasticsearch#Python considerations.

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