Recommended way to run my scripts from a venv? (feddit.org)

submitted 5 months ago by Schmerzbold@feddit.org to c/python@programming.dev

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So, I have a python script I'd like to run from time to time from the CLI (on Linux) that resides inside a venv. What's the recommended/intended way to do this?
Write a wrapper shell script and put it inside a $PATH-accessible directory that activates the virtual environment, runs the python script and deactivates the venv again? This seems a bit convoluted, but I can't think of a better way.

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[-] lakeeffect@lemmy.world 26 points 5 months ago

Use venv/bin/python app.py to run it.

[-] Schmerzbold@feddit.org 5 points 5 months ago

That works nicely. Thanks 👍

[-] Andy@programming.dev 2 points 5 months ago

I use my own Zsh project (zpy) to manage venvs stored like ~/.local/share/venvs/HASH-OF-PROJECT-PATH/venv, so use zpy's vpy function to launch a script with its associated Python executable ad-hoc, or add a full path shebang to the script with zpy's vpyshebang function.

vpy and vpyshebang in the docs

If anyone else is a Zsh fan and has any questions, I'm more than happy to answer or demo.

[-] faulkmore@mastodon.social 1 points 5 months ago

@Andy The convention is to place the venv in a .venv/ sub folder. Follow the convention!

This is shell agnostic

Learn pyenv and minimize shell scripts (only lives within a Makefile).

Shell scripts within Python packages is depreciated

[-] Andy@programming.dev 2 points 5 months ago

The convention

That's one convention. I don't like it, I prefer to keep my venvs elsewhere. One reason is that it makes it simpler to maintain multiple venvs for a single project, using a different Python version for each, if I ever want to. It shouldn't matter to anyone else, as it's my environment, not some aspect of the shared repo. If I ever needed it there for some reason, I could always ln -s $VIRTUAL_ENV .venv.

Learn pyenv

I have used pyenv. It's fine. These days I use mise instead, which I prefer. But neither of them dictate how I create and store venvs.

Shell scripts within Python packages is depreciated

I don't understand if what you're referencing relates to my comment.

[-] logging_strict@programming.dev 1 points 5 months ago

The multiple venv for different Python versions sounds exactly like what tox does

Then setup a github action that does nightly builds. Which will catch issues caused by changes that only tested against one python version or on one platform

py313 is a good version to test against cuz there were many modules removed or depreciated or APIs changed

good luck. Hope some of my advice is helpful

[-] Andy@programming.dev 2 points 5 months ago

Thanks, yes, I use nox and github actions for automated environments and testing in my own projects, and tox instead of nox when it's someone else's project. But for ad hoc, local and interactive multiple environments, I don't.

[-] logging_strict@programming.dev 1 points 1 month ago

thanks for the head up on nox. Syntax seems like a tox meets pytest.

[-] logging_strict@programming.dev 1 points 1 month ago

Are you using github actions locally? Feel silly making gh actions and workflows and only github runs them

[-] Andy@programming.dev 1 points 1 month ago

No, I don't use GHA locally, but the actions are defined to run the same things that I do run locally (e.g. invoke nox). I try to keep the GHA-exclusive boilerplate to a minimum. Steps can be like:

- name: fetch code
  uses: actions/checkout@v4

- uses: actions/setup-python@v5
  with:
    allow-prereleases: true
    python-version: |
      3.13
      3.12
      3.11
      3.10
      3.9
      3.8
      3.7

- run: pipx install nox

- name: run ward tests in nox environment
  run: nox -s test test_without_toml combine_coverage --force-color
  env:
    PYTHONIOENCODING: utf-8

- name: upload coverage data
  uses: codecov/codecov-action@v4
  with:
    files: ./coverage.json
    token: ${{ secrets.CODECOV_TOKEN }}

Sometimes if I want a higher level interface to tasks that run nox or other things locally, I use taskipy to define them in my pyproject.toml, like:

[tool.taskipy.tasks]
fmt = "nox -s fmt"
lock = "nox -s lock"
test = "nox -s test test_without_toml typecheck -p 3.12"
docs = "nox -s render_readme render_api_docs"

[-] logging_strict@programming.dev 1 points 1 month ago

Thanks for the introduction to taskipy. Think if i need macros, Makefile is the way to go. Supports running targets in parallel and i like performing a check to ensure the virtual environment is activated or the command won't run.

.ONESHELL:
.DEFAULT_GOAL := help
SHELL := /bin/bash
APP_NAME := logging_strict

#virtual environment. If 0 issue warning
#Not activated:0
#activated: 1
ifeq ($(VIRTUAL_ENV),)
$(warning virtualenv not activated)
is_venv =
else
is_venv = 1
VENV_BIN := $(VIRTUAL_ENV)/bin
VENV_BIN_PYTHON := python3
PY_X_Y := $(shell $(VENV_BIN_PYTHON) -c 'import platform; t_ver = platform.python_version_tuple(); print(".".join(t_ver[:2]));')
endif

.PHONY: mypy
mypy:					## Static type checker (in strict mode)
ifeq ($(is_venv),1)
	@$(VENV_BIN_PYTHON) -m mypy -p $(APP_NAME)
endif

make mypy without the virtualenv on will write a warning message why it's not working!

[-] Andy@programming.dev 1 points 1 month ago* (last edited 1 month ago)

Sure, but nox is the closer counterpart for in-venv-task definitions. List "sessions" with -l, pick specific sessions to run with -s.

import nox
from nox.sessions import Session

nox.options.reuse_existing_virtualenvs = True
APP_NAME = 'logging_strict'

@nox.session(python='3.12')
def mypy(session: Session):
    """Static type checker (in strict mode)"""
    session.install('-U', 'mypy', '.')
    session.run('mypy',  '-p', APP_NAME, *session.posargs)

Unfortunately it doesn't currently do any parallel runs, but if anyone wants to track/encourage/contribute in that regard, see nox#544.

[-] Violet_McQuasional@feddit.uk 2 points 5 months ago

This. I've experimented by using pex before and one or two other means of executable python wrappers and they suck. Just do as lakeeffect says.

[-] MajorHavoc@programming.dev 1 points 5 months ago

Yep. This is the way.

[-] kionite231@lemmy.ca 1 points 5 months ago

I think the path to venv should be absolute right?

[-] lakeeffect@lemmy.world 1 points 5 months ago

Yeah, for the most part but really depends on what you’re trying to do specifically.

[-] logging_strict@programming.dev 1 points 5 months ago

Just activate the venv and then put it out of your mind. Can activate it with either a relative or absolute path. Doesn't matter which

[-] gitamar@feddit.de 3 points 5 months ago

I use pipenv with pyenv together. This works pretty well, also in cron jobs. Just add pipenv run python script.py to the cron table.

[-] namingthingsiseasy@programming.dev 2 points 5 months ago

Just in case this comment didn't make it explicitly clear, you can just invoke the python binary inside your venv directly and it will automatically locate all the libraries that are installed in your virtual environment.

To show how this works, you can look at the sys.path variable to see which paths python will search for modules when you run import statements. Try running python3 -c 'import sys; print(sys.path)' using your system python, and you will only see system python library paths. Then, try running it again after replacing python3 with the full path to the python3 binary in your venv, and you will see an additional entry in the output with the lib directory in your venv, which shows that python will also look there for modules when an import statement is executed.