settings.py

import imp
import os
import stat
import string
import sys

from default_settings import *

def get_arg(key):
    return sys.argv[sys.argv.index(key) + 1]

def get_args(key):
    args = []
    _ = 0
    while True:
        try:
            _ = sys.argv.index(key, _) + 1
            args.append(sys.argv[_])
            _ += 1
        except ValueError:
            break
    return args

def load_config():

    conf_file = '/etc/service/service.conf'

    if '--config' in sys.argv:
        conf_file = get_arg('--config')

    if not os.path.exists(conf_file):
        # XXX: need to configure logging before importing config
        sys.stderr.write('Config file %s does not exist!\n' % conf_file)
        return object()

    if not bool(os.stat(conf_file).st_mode & stat.S_IREAD):
        sys.stderr.write('Config file %s is not readable!\n' % conf_file)
        return object()

    # make module name suitable for logging
    mod_name = '.'.join([
        __name__,
        os.path.basename(conf_file).rpartition('.')[0]
    ])

    try:
        # it is here for imports in conf_file
        sys.path.insert(0, os.path.dirname(conf_file))
        # load it
        ret = imp.load_source(mod_name, conf_file)
        # remove its dir from path, it is not needed now
        del sys.path[0]
        return ret
    except ImportError as exc:
        sys.stderr.write("Can't import config file %s!" % conf_file)
        raise exc

# LOAD CONFIG PARAMETERS
config = load_config()

# Update globals with config.[A-Z]*
globals().update((i, getattr(config, i)) for i in dir(config)
                 if i[0] in string.ascii_uppercase)