install_tools.py

import getpass
import os
import re
from subprocess import Popen, PIPE

class Environ(object):
    """ Context manager that sets and restores an environment variable """
    def __init__(self, var, value):
        self.env_var = var
        self.new_value = value

    def __enter__(self):
        self.start_value = os.environ.get(self.env_var, None)
        os.environ[self.env_var] = self.new_value
        return self.new_value

    def __exit__(self, type, value, traceback):
        if self.start_value is not None:
            os.environ[self.env_var] = self.start_value
        else:
            del os.environ[self.env_var]

class CD(object):
    """ Context manager to change and restore the current working directory """
    def __init__(self, new_dir):
        self.new_dir = new_dir

    def __enter__(self):
        self.org_dir = os.getcwd()
        os.chdir(self.new_dir)
        return self.new_dir

    def __exit__(self, type, value, traceback):
        os.chdir(self.org_dir)

def file_contains(filename, line_pattern):
    """ Checks if a file has a line matching the given pattern """
    if not os.path.exists(filename):
        return False
    regex = re.compile(line_pattern)
    with open(filename, 'r') as src:
        for line in src:
            if regex.search(line):
                return True
    return False

def append_line(filename, line):
    """ Appends a line to a file """
    with open(filename, "a+") as afile:
        afile.write(line + '\n')

class CmdError(StandardError):
    """ Exception raised on an error return code results from run_cmd """
    def __init__(self, cmd, returncode):
        self.cmd = cmd
        self.returncode = returncode
        StandardError.__init__(self, "Error %s returned from %s"
            % (returncode, cmd))

def run_cmd(cmd, capture_stdout=False):
    """ Run a command in a shell """
    print "Executing:", cmd
    stdout_loc = PIPE if capture_stdout else None
    proc = Popen(cmd, shell=True, stdout=stdout_loc)
    output, error_out = proc.communicate()
    status = proc.wait()
    if status != 0:
        raise CmdError(cmd, status)
    return output

def install_apt_packages(packages):
    """ Install system packages using aptitude """
    apt_cmd = "apt-get install -y "
    try:
        cmd = apt_cmd + packages
    except TypeError:
        cmd = apt_cmd + " ".join(packages)
    run_cmd(cmd)

def get_choice(query, default=False):
    negative_responses = ["no", "n"]
    positive_responses = ["yes", "y"]
    query += " [%s] " % ('yes' if default else 'no')
    while True:
        resp = raw_input(query).lower().strip()
        if resp in negative_responses or (resp == "" and not default):
            return False
        if resp in positive_responses or (resp == "" and default):
            return True

def get_password(pw_name):
    while True:
        passwd = getpass.getpass("%s password? " % (pw_name.capitalize()))
        confirm = getpass.getpass("Confirm %s password? " % (pw_name,))
        if passwd == confirm:
            return passwd
        print "Sorry, passwords did not match."

def get_ubuntu_release_info():
    version="notubuntu"
    arch="unknown"
    try:
        version=re.match(".*DISTRIB_CODENAME=(\w*).*",open("/etc/lsb-release").read(),re.DOTALL).group(1)
        arch=run_cmd("dpkg --print-architecture",True).strip()
    except CmdError, IOError:
        arch=run_cmd("uname -p",True).strip()
    except:
        pass
    
    return version, arch

def check_ubuntu_version():
    version,arch=get_ubuntu_release_info()
    if version!="notubuntu":
        print "Install tools on Ubuntu version:%s arch:%s." % (version, arch)
    else:
        print "Installing on an %s non-Ubuntu host." % (arch)
    
    if version!="natty":
        raise Exception("This contest framework was designed to work on Ubuntu Natty(11.04) only.")
    
    return version, arch