Install R packages on ShinyServerPro

rpkg.py

#!/usr/bin/env python
"""
Install R Packages from the command line

Usage: (parse app.R)
    ./rpkg app.R

Usage: (install R packages)
    ./rpkg shiny V8 plyr
"""
import os
import pwd
import shlex
import subprocess
import sys

E_OK = 0
E_BADARGS = 1

# The name of the shiny user
SHINY_USER_NAME = 'shiny'

def loadfile(filename):
    """
    
    :param filename:
    :return:
    """
    with open(filename, 'r') as fd:
        return filter(lambda l: l.startswith('require('),
                       [line.strip() for line in fd.readlines()])

def change_user(uid, gid):
    """
    Returns a pre-exec function to pass to subprocess.Popen
    This allows the script to run as the 'shiny' user
    (defined in SHINY_USER_NAME)

    :param uid: int
    :param gid: int
    :return: function
    """
    def wrapper():
        os.setgid(gid)
        os.setuid(uid)
    return wrapper

def get_install_command(package):
    return shlex.split("R -e \'install.packages(\"%s\", repos=\"http://cran.rstudio.com/\")\'".format(package)

def get_new_env(username):
    """
    Build up an environment for the new user

    :param username:
    :return:
    """
    info = pwd.getpwnam(username)
    env = os.environ.copy()
    env['HOME'] = info.pw_dir
    env['LOGNAME'] = info.pw_name
    env['PWD'] = os.getcwd()
    env['USER'] = info.pw_name

    cwd = os.getcwd()

    preexec = change_user(info.pw_uid, info.pw_gid)
    return env, cwd, preexec

def install_package(package):
    """
    Installs an R package

    :param package: The name of the package to install
     :type package: str
    :return:
    """
    print(">> Installing '{}'".format(package))
    env, cwd, preexec = get_new_env(SHINY_USER_NAME)

    ps = subprocess.Popen(get_install_command(package),
                          preexec_fn=preexec,
                          cwd=cwd,
                          env=env,
                          stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE)
    _out, _err = ps.communicate()

    success_str = "* DONE ({})".format(package)

    if success_str not in _err:
        print("\033[31mERROR")
        print(_err)
        print("\033[0m")
        return False

    print("    [\033[32mOK\033[0m]")
    return True

def install_packages(packages):
    """
    Mostly unnecessary, unless you run into exceptions
    Add the install_package call inside a try:except block
    to install *most* packages

    :param packages:
    :return:
    """
    for package in packages:
        install_package(package)

def main(filename):
    """

    :param filename:
    :return:
    """
    packages = []

    if os.path.exists(filename):
        # Parse a file
        lines = loadfile(filename)

        for require in lines:
            packages.append(require.replace('require(', '').replace(')', ''))
    else:
        # Install a list of packages
        for arg in sys.argv[1:]:
            packages.append(arg)

    install_packages(packages)


if __name__ == '__main__':
    try:
        infile = sys.argv[1]
    except IndexError:
        print("Usage: {0} <path/to/app.R>\nOr: {1} list of packages".format(sys.argv[0], sys.argv[0]))

	exit(E_BADARGS)

    exit(main(infile))