Rudimentary NPM-like script for Python (using PIP)

ppm.py

#!/usr/bin/env python3
import json
import argparse
import subprocess
import os
import pip

def find_package_root():
    path = os.path.abspath('.')
    files = [f for f in os.listdir(path) if os.path.isfile(os.path.join(path, f))]
    while 'package.json' not in files and path != '/':
        path = os.path.dirname(path)
        files = [f for f in os.listdir(path) if os.path.isfile(os.path.join(path, f))]

    if path == '/':
        raise FileNotFoundError('Unable to locate package.json')
    return path

def load_package(root):
    with open(os.path.join(root, 'package.json')) as pkgfile:
        return json.load(pkgfile)

package_root = find_package_root()
package = load_package(package_root)

def install(packages, dest_dir="python_modules"):
    pip.main(['install', '--target', os.path.join(package_root, "python_modules/")] + [name + version for name,version in package['dependencies'].items()])

def merge_env(new_env):
    return dict(list(os.environ.items()) + list(new_env.items()))

def run(ns):
    process = subprocess.Popen(['/usr/bin/python3', os.path.join(package_root, package['main'])] + ns.args,
                               env=merge_env({"PYTHONPATH": os.path.join(package_root, "python_modules/")}))
    process.wait()

def main():
    parser = argparse.ArgumentParser(description="NPM for Python")
    command_parsers = parser.add_subparsers(description="")

    # run [args]
    run_parser = command_parsers.add_parser('run', help='Run application')
    run_parser.add_argument("args", nargs=argparse.REMAINDER)
    run_parser.set_defaults(func=run)

    # install
    install_parser = command_parsers.add_parser('install', help='Install dependencies')
    install_parser.set_defaults(func=install)

    args = parser.parse_args()
    args.func(args)

if __name__ == "__main__":
    main()