Thinking about python virtualenvs and node/npm

virtualenv-js

#! /usr/bin/env python

import os
import tempfile
import shutil
import tarfile
import sys
import subprocess
import optparse


NPM_URL = "http://registry.npmjs.org/npm/-/npm-1.3.23.tgz"

def search_path(b):
    path = os.environ.get("PATH", "/usr/bin").split(":")
    for p in path:
        binary = os.path.join(p, b)
        if os.path.exists(binary):
            return binary


def bootstrap_npm_from_internet(virtualenv_dir, node=None):
    # This method can install NPM when no NPM is available. In practice this
    # doesn't happen any more - npm ships with nodejs these days

    node = node or search_path("node")
    if not node:
        return False

    d = tempfile.mkdtemp(dir=virtualenv_dir)
    try:
        package_tgz = os.path.join(d, "npm.tgz")
        package_dir = os.path.join(d, "npm")
        cli_js = os.path.join(package_dir, "package", "cli.js")

        print("-> Downloading npm bootstrap (%s)" % NPM_URL)
        try:
            import urllib.request
            urllib.request.urlretrieve(NPM_URL, package_tgz)
        except ImportError:
            import urllib
            urllib.urlretrieve(NPM_URL, package_tgz)

        print("-> Extracting")
        t = tarfile.open(package_tgz)
        t.extractall(package_dir)

        print("-> Installing")
        subprocess.check_call([node, cli_js, "install", "-g", "--prefix", virtualenv_dir, "npm"])
    finally:
        shutil.rmtree(d)


def bootstrap_npm_from_npm(virtualenv_dir):
    # Given a working npm, install it somewhere else
    print("-> Installing")
    npm = search_path("npm")
    if not npm:
        return False
    subprocess.check_call([npm, "install", "-g", "--prefix", virtualenv_dir, "npm"])
    return True


def setup_virtualenv(virtualenv_dir, node=None):
    virtualenv_dir = os.path.abspath(virtualenv_dir)
    bin_dir = os.path.join(virtualenv_dir, "bin")
    lib_dir = os.path.join(virtualenv_dir, "lib")
    node_modules_dir = os.path.join(lib_dir, "node_modules")

    if not os.path.exists(os.path.join(bin_dir, "npm")):
        if not bootstrap_npm_from_npm(virtualenv_dir):
            if not bootstrap_npm_from_internet(virtualenv_dir, node=node):
                print("Cannot find existing 'npm'/'node'")
                sys.exit(1)

    print("-> Setting npm default settings")
    with open(os.path.join(node_modules_dir, "npm", "npmrc"), "w") as fp:
        fp.write("\n".join([
            "prefix=%s" % virtualenv_dir,
            "global=true",
            ]))

    print("Done.")


if __name__ == "__main__":
    p = optparse.OptionParser()
    p.add_option("-n", "--node")
    opts, args = p.parse_args()

    if len(args) != 1:
        p.print_help()
        sys.exit(1)

    setup_virtualenv(args[0], node=opts.node)