Python: How to create a virtual environment at temp dir and install modules with pip

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I want to create a temp file and write a python script. I want to create a virtual environment at this temp dir and use pip and then run this script with the virtual environment.

import pathlib
import tempfile 
import venv

temp = tempfile.TemporaryDirectory()

virtualenv = venv.EnvBuilder(system_site_packages=false)
virtualenv.create(temp.name)

# how could I activate the virtual environment and install the pip module?

with open(pathlib.Path(temp.name)/"run.py", "w") as f:
    f.write("#/usr/bin/env python\n\n")
    f.write("import requests\n")

p = subprocess.run(["python", temp.name", "run.py"])
pathlib python-venv pip temporary-files python
1 Answers

I believe the following should achieve your expectations:

#!/usr/bin/env python3

import pathlib
import string
import subprocess
import tempfile
import venv

SCRIPT_TEMPLATE = '''\
#!${venv_executable}

import requests
print(requests)
'''

class EnvBuilder(venv.EnvBuilder):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.context = None

    def post_setup(self, context):
        self.context = context

def main():
    with tempfile.TemporaryDirectory() as target_dir_path:
        print(f" *** Created temporary directory '{target_dir_path}'.")
        #
        print(f" *** Creating virtual environment...")
        venv_builder = EnvBuilder(with_pip=True)
        venv_builder.create(str(target_dir_path))
        venv_context = venv_builder.context
        #
        requirements = [
            'requests',
        ]
        print(f" *** Installing {requirements}...")
        pip_install_command = [
            venv_context.env_exe,
            '-m',
            'pip',
            'install',
            *requirements,
        ]
        subprocess.check_call(pip_install_command)
        #
        print(" *** Generating script...")
        script_substitutions = {
            'venv_executable': venv_context.env_exe,
        }
        script = (
            string.Template(SCRIPT_TEMPLATE).substitute(script_substitutions)
        )
        print(" *** Generated script:")
        print("'''")
        print(script)
        print("'''")
        #
        script_path = pathlib.Path(target_dir_path).joinpath('run.py')
        print(f" *** Writing script '{script_path}'")
        script_path.write_text(script)
        #
        print(" *** Executing script...")
        script_command = [
            venv_context.env_exe,
            str(script_path),
        ]
        subprocess.check_call(script_command)

if __name__ == '__main__':
    main()
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