freeipa/ipalib/config.py

# Authors:
#   Martin Nagy <mnagy@redhat.com>
#
# Copyright (C) 2008  Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; version 2 only
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

"""
Basic configuration management.

This module handles the reading and representation of basic local settings.
It will also take care of settings that can be discovered by different
methods, such as DNS.
"""

from ConfigParser import RawConfigParser, ParsingError
from types import NoneType
import os
from os import path
import sys
from constants import CONFIG_SECTION
from constants import TYPE_ERROR, OVERRIDE_ERROR, SET_ERROR, DEL_ERROR


class Env(object):
    """
    Store and retrieve environment variables.

    First an foremost, the `Env` class provides a handy container for
    environment variables.  These variables can be both set and retrieved as
    either attributes or as dictionary items.

    For example, we can set a variable as an attribute:

    >>> env = Env()
    >>> env.attr = 'I was set as an attribute.'
    >>> env.attr  # Retrieve as an attribute
    'I was set as an attribute.'
    >>> env['attr']  # Also retrieve as a dictionary item
    'I was set as an attribute.'

    Or we can set a variable as a dictionary item:

    >>> env['item'] = 'I was set as a dictionary item.'
    >>> env['item']  # Retrieve as a dictionary item
    'I was set as a dictionary item.'
    >>> env.item  # Also retrieve as an attribute
    'I was set as a dictionary item.'

    The variable values can be ``str`` or ``int`` instances, or the ``True``,
    ``False``, or ``None`` constants.  When the value provided is an ``str``
    instance, some limited automatic type conversion is performed, which allows
    values of specific types to be set easily from configuration files and from
    command-line options.

    The ``True``, ``False``, and ``None`` constants can be specified with a
    string that matches what ``repr()`` would return.  For example:

    >>> env.true = 'True'
    >>> env.true
    True

    Note that the automatic type conversion is case sensitive.  For example:

    >>> env.false = 'false'  # Doesn't match repr(False)
    >>> env.false
    'false'

    If an ``str`` value looks like an integer, it's automatically converted to
    the ``int`` type.  For example:

    >>> env.lucky = '7'
    >>> env.lucky
    7

    Also, leading and trailing white-space is automatically stripped from
    ``str`` values.  For example:

    >>> env.message = '  Hello!  '  # Surrounded by double spaces
    >>> env.message
    'Hello!'
    >>> env.number = '42 '  # Still converted to an int
    >>> env.number
    42
    >>> env.actually_false = ' False'  # Still matches repr(False)
    >>> env.actually_false
    False

    `Env` is set-once, first-one-wins.  Once a variable has been set, trying to
    override it will raise an ``AttributeError``.  For example:

    >>> env.my_var = 'first'
    >>> env.my_var = 'second'
    Traceback (most recent call last):
      ...
    AttributeError: cannot override Env.my_var value 'first' with 'second'

    An `Env` instance can also be *locked*, after which no further variables can
    be set.  Trying to set variables on a locked `Env` instance will also raise
    an ``AttributeError``.  For example:

    >>> env = Env()
    >>> env.var1 = 'This will work.'
    >>> env.__lock__()
    >>> env.var2 = 'This wont work!'
    Traceback (most recent call last):
      ...
    AttributeError: locked: cannot set Env.var2 to 'This wont work!'

    Finish me!
    """

    __locked = False

    def __init__(self):
        object.__setattr__(self, '_Env__d', {})
        object.__setattr__(self, '_Env__done', set())
        self.ipalib = path.dirname(path.abspath(__file__))
        self.site_packages = path.dirname(self.ipalib)
        self.script = path.abspath(sys.argv[0])
        self.bin = path.dirname(self.script)
        self.home = path.abspath(os.environ['HOME'])
        self.dot_ipa = path.join(self.home, '.ipa')

    def __setattr__(self, name, value):
        """
        Set the attribute named ``name`` to ``value``.

        This just calls `Env.__setitem__()`.
        """
        self[name] = value

    def __setitem__(self, key, value):
        """
        Set ``key`` to ``value``.
        """
        # FIXME: the key should be checked with check_name()
        if self.__locked:
            raise AttributeError(
                SET_ERROR % (self.__class__.__name__, key, value)
            )
        if key in self.__d:
            raise AttributeError(OVERRIDE_ERROR %
                (self.__class__.__name__, key, self.__d[key], value)
            )
        if hasattr(self, key):
            raise AttributeError(OVERRIDE_ERROR %
                (self.__class__.__name__, key, getattr(self, key), value)
            )
        if isinstance(value, basestring):
            value = str(value.strip())
            m = {
                'True': True,
                'False': False,
                'None': None,
            }
            if value in m:
                value = m[value]
            elif value.isdigit():
                value = int(value)
        assert type(value) in (str, int, bool, NoneType)
        object.__setattr__(self, key, value)
        self.__d[key] = value

    def __getitem__(self, key):
        """
        Return the value corresponding to ``key``.
        """
        return self.__d[key]

    def __delattr__(self, name):
        """
        Raise AttributeError (deletion is never allowed).
        """
        raise AttributeError(
            DEL_ERROR % (self.__class__.__name__, name)
        )

    def __doing(self, name):
        if name in self.__done:
            raise StandardError(
                '%s.%s() already called' % (self.__class__.__name__, name)
            )
        self.__done.add(name)

    def __do_if_not_done(self, name):
        if name not in self.__done:
            getattr(self, name)()

    def _isdone(self, name):
        return name in self.__done

    def _bootstrap(self, **overrides):
        """
        Initialize basic environment.

        This method will initialize only enough environment information to
        determine whether ipa is running in-tree, what the context is,
        and the location of the configuration file.
        """
        self.__doing('_bootstrap')
        for (key, value) in overrides.iteritems():
            self[key] = value
        if 'in_tree' not in self:
            if self.bin == self.site_packages and \
                    path.isfile(path.join(self.bin, 'setup.py')):
                self.in_tree = True
            else:
                self.in_tree = False
        if 'context' not in self:
            self.context = 'default'
        if self.in_tree:
            base = self.dot_ipa
        else:
            base = path.join('/', 'etc', 'ipa')
        if 'conf' not in self:
            self.conf = path.join(base, '%s.conf' % self.context)
        if 'conf_default' not in self:
            self.conf_default = path.join(base, 'default.conf')
        if 'conf_dir' not in self:
            self.conf_dir = base

    def _finalize_core(self, **defaults):
        """
        Complete initialization of standard IPA environment.

        After this method is called, the all environment variables
        used by all the built-in plugins will be available.

        This method should be called before loading any plugins. It will
        automatically call `Env._bootstrap()` if it has not yet been called.

        After this method has finished, the `Env` instance is still writable
        so that third
        """
        self.__doing('_finalize_core')
        self.__do_if_not_done('_bootstrap')
        if self.__d.get('mode', None) != 'dummy':
            self._merge_config(self.conf)
            self._merge_config(self.conf_default)
        if 'in_server' not in self:
            self.in_server = (self.context == 'server')
        if 'log' not in self:
            name = '%s.log' % self.context
            if self.in_tree or self.context == 'cli':
                self.log = path.join(self.dot_ipa, 'log', name)
            else:
                self.log = path.join('/', 'var', 'log', 'ipa', name)
        for (key, value) in defaults.iteritems():
            if key not in self:
                self[key] = value

    def _finalize(self, **lastchance):
        """
        Finalize and lock environment.

        This method should be called after all plugins have bean loaded and
        after `plugable.API.finalize()` has been called.
        """
        self.__doing('_finalize')
        self.__do_if_not_done('_finalize_core')
        for (key, value) in lastchance.iteritems():
            if key not in self:
                self[key] = value
        self.__lock__()

    def _merge_config(self, conf_file):
        """
        Merge values from ``conf_file`` into this `Env`.
        """
        if not path.isfile(conf_file):
            return
        parser = RawConfigParser()
        try:
            parser.read(conf_file)
        except ParsingError:
            return
        if not parser.has_section(CONFIG_SECTION):
            parser.add_section(CONFIG_SECTION)
        items = parser.items(CONFIG_SECTION)
        if len(items) == 0:
            return
        i = 0
        for (key, value) in items:
            if key not in self:
                self[key] = value
                i += 1
        return (i, len(items))

    def __lock__(self):
        """
        Prevent further changes to environment.
        """
        if self.__locked is True:
            raise StandardError(
                '%s.__lock__() already called' % self.__class__.__name__
            )
        object.__setattr__(self, '_Env__locked', True)

    def __islocked__(self):
        return self.__locked







    def __contains__(self, key):
        """
        Return True if instance contains ``key``; otherwise return False.
        """
        return key in self.__d

    def __len__(self):
        """
        Return number of variables currently set.
        """
        return len(self.__d)

    def __iter__(self):
        """
        Iterate through keys in ascending order.
        """
        for key in sorted(self.__d):
            yield key