install_dependencies.py

import bpy
import os
import sys
import subprocess
import importlib

def import_module(module_name, global_name=None, reload=True):
    """
    Import a module.
    :param module_name: Module to import.
    :param global_name: (Optional) Name under which the module is imported. If None the module_name will be used.
       This allows to import under a different name with the same effect as e.g. "import numpy as np" where "np" is
       the global_name under which the module can be accessed.
    :raises: ImportError and ModuleNotFoundError
    """
    if global_name is None:
        global_name = module_name

    if global_name in globals():
        importlib.reload(globals()[global_name])
    else:
        # Attempt to import the module and assign it to globals dictionary. This allow to access the module under
        # the given name, just like the regular import would.
        globals()[global_name] = importlib.import_module(module_name)


def install_pip():
    """
    Installs pip if not already present. Please note that ensurepip.bootstrap() also calls pip, which adds the
    environment variable PIP_REQ_TRACKER. After ensurepip.bootstrap() finishes execution, the directory doesn't exist
    anymore. However, when subprocess is used to call pip, in order to install a package, the environment variables
    still contain PIP_REQ_TRACKER with the now nonexistent path. This is a problem since pip checks if PIP_REQ_TRACKER
    is set and if it is, attempts to use it as temp directory. This would result in an error because the
    directory can't be found. Therefore, PIP_REQ_TRACKER needs to be removed from environment variables.
    :return:
    """

    try:
        # Check if pip is already installed
        subprocess.run([sys.executable, "-m", "pip", "--version"], check=True)
    except subprocess.CalledProcessError:
        import ensurepip

        ensurepip.bootstrap()
        os.environ.pop("PIP_REQ_TRACKER", None)


def install_and_import_requirements(requirements, target):
    """
    Installs the package through pip and attempts to import the installed module.
    :param module_name: Module to import.
    :param package_name: (Optional) Name of the package that needs to be installed. If None it is assumed to be equal
       to the module_name.
    :param global_name: (Optional) Name under which the module is imported. If None the module_name will be used.
       This allows to import under a different name with the same effect as e.g. "import numpy as np" where "np" is
       the global_name under which the module can be accessed.
    :raises: subprocess.CalledProcessError and ImportError
    """

    # Create a copy of the environment variables and modify them for the subprocess call
    environ_copy = dict(os.environ)
    environ_copy["PYTHONNOUSERSITE"] = "1"

    subprocess.run([sys.executable, "-m", "pip", "install",  "-r", requirements,  "--no-cache-dir", "--target", target], check=True, env=environ_copy)