summaryrefslogtreecommitdiffstats
path: root/ipalib/plugable.py
blob: c0a4c3567cc439d14ff1562a89bae7084f99b4d3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
# Authors:
#   Jason Gerard DeRose <jderose@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

"""
Plugin framework.

The classes in this module make heavy use of Python container emulation. If
you are unfamiliar with this Python feature, see
http://docs.python.org/ref/sequence-types.html
"""

import re
import sys
import inspect
import threading
import logging
import os
from os import path
import subprocess
import optparse
import errors
from config import Env
import util
from base import ReadOnly, NameSpace, lock, islocked, check_name
from constants import DEFAULT_CONFIG, FORMAT_STDERR, FORMAT_FILE


class SetProxy(ReadOnly):
    """
    A read-only container with set/sequence behaviour.

    This container acts as a proxy to an actual set-like object (a set,
    frozenset, or dict) that is passed to the constructor. To the extent
    possible in Python, this underlying set-like object cannot be modified
    through the SetProxy... which just means you wont do it accidentally.
    """
    def __init__(self, s):
        """
        :param s: The target set-like object (a set, frozenset, or dict)
        """
        allowed = (set, frozenset, dict)
        if type(s) not in allowed:
            raise TypeError('%r not in %r' % (type(s), allowed))
        self.__s = s
        lock(self)

    def __len__(self):
        """
        Return the number of items in this container.
        """
        return len(self.__s)

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

    def __contains__(self, key):
        """
        Return True if this container contains ``key``.

        :param key: The key to test for membership.
        """
        return key in self.__s


class DictProxy(SetProxy):
    """
    A read-only container with mapping behaviour.

    This container acts as a proxy to an actual mapping object (a dict) that
    is passed to the constructor. To the extent possible in Python, this
    underlying mapping object cannot be modified through the DictProxy...
    which just means you wont do it accidentally.

    Also see `SetProxy`.
    """
    def __init__(self, d):
        """
        :param d: The target mapping object (a dict)
        """
        if type(d) is not dict:
            raise TypeError('%r is not %r' % (type(d), dict))
        self.__d = d
        super(DictProxy, self).__init__(d)

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

        :param key: The key of the value you wish to retrieve.
        """
        return self.__d[key]

    def __call__(self):
        """
        Iterate (in ascending order by key) through values.
        """
        for key in self:
            yield self.__d[key]


class MagicDict(DictProxy):
    """
    A mapping container whose values can be accessed as attributes.

    For example:

    >>> magic = MagicDict({'the_key': 'the value'})
    >>> magic['the_key']
    'the value'
    >>> magic.the_key
    'the value'

    This container acts as a proxy to an actual mapping object (a dict) that
    is passed to the constructor. To the extent possible in Python, this
    underlying mapping object cannot be modified through the MagicDict...
    which just means you wont do it accidentally.

    Also see `DictProxy` and `SetProxy`.
    """

    def __getattr__(self, name):
        """
        Return the value corresponding to ``name``.

        :param name: The name of the attribute you wish to retrieve.
        """
        try:
            return self[name]
        except KeyError:
            raise AttributeError('no magic attribute %r' % name)


class Plugin(ReadOnly):
    """
    Base class for all plugins.
    """
    __public__ = frozenset()
    __proxy__ = True
    __api = None

    def __init__(self):
        cls = self.__class__
        self.name = cls.__name__
        self.module = cls.__module__
        self.fullname = '%s.%s' % (self.module, self.name)
        self.doc = inspect.getdoc(cls)
        if self.doc is None:
            self.summary = '<%s>' % self.fullname
        else:
            self.summary = self.doc.split('\n\n', 1)[0]
        log = logging.getLogger(self.fullname)
        for name in ('debug', 'info', 'warning', 'error', 'critical', 'exception'):
            if hasattr(self, name):
                raise StandardError(
                    '%s.%s attribute (%r) conflicts with Plugin logger' % (
                        self.name, name, getattr(self, name))
                )
            setattr(self, name, getattr(log, name))

    def __get_api(self):
        """
        Return `API` instance passed to `finalize()`.

        If `finalize()` has not yet been called, None is returned.
        """
        return self.__api
    api = property(__get_api)

    @classmethod
    def implements(cls, arg):
        """
        Return True if this class implements ``arg``.

        There are three different ways this method can be called:

        With a <type 'str'> argument, e.g.:

        >>> class base(Plugin):
        ...     __public__ = frozenset(['attr1', 'attr2'])
        ...
        >>> base.implements('attr1')
        True
        >>> base.implements('attr2')
        True
        >>> base.implements('attr3')
        False

        With a <type 'frozenset'> argument, e.g.:

        With any object that has a `__public__` attribute that is
        <type 'frozenset'>, e.g.:

        Unlike ProxyTarget.implemented_by(), this returns an abstract answer
        because only the __public__ frozenset is checked... a ProxyTarget
        need not itself have attributes for all names in __public__
        (subclasses might provide them).
        """
        assert type(cls.__public__) is frozenset
        if isinstance(arg, str):
            return arg in cls.__public__
        if type(getattr(arg, '__public__', None)) is frozenset:
            return cls.__public__.issuperset(arg.__public__)
        if type(arg) is frozenset:
            return cls.__public__.issuperset(arg)
        raise TypeError(
            "must be str, frozenset, or have frozenset '__public__' attribute"
        )

    @classmethod
    def implemented_by(cls, arg):
        """
        Return True if ``arg`` implements public interface of this class.

        This classmethod returns True if:

        1. ``arg`` is an instance of or subclass of this class, and

        2. ``arg`` (or ``arg.__class__`` if instance) has an attribute for
           each name in this class's ``__public__`` frozenset.

        Otherwise, returns False.

        Unlike `Plugin.implements`, this returns a concrete answer because
        the attributes of the subclass are checked.

        :param arg: An instance of or subclass of this class.
        """
        if inspect.isclass(arg):
            subclass = arg
        else:
            subclass = arg.__class__
        assert issubclass(subclass, cls), 'must be subclass of %r' % cls
        for name in cls.__public__:
            if not hasattr(subclass, name):
                return False
        return True

    def finalize(self):
        """
        """
        lock(self)

    def set_api(self, api):
        """
        Set reference to `API` instance.
        """
        assert self.__api is None, 'set_api() can only be called once'
        assert api is not None, 'set_api() argument cannot be None'
        self.__api = api
        if not isinstance(api, API):
            return
        for name in api:
            assert not hasattr(self, name)
            setattr(self, name, api[name])
        # FIXME: the 'log' attribute is depreciated.  See Plugin.__init__()
        for name in ('env', 'context', 'log'):
            if hasattr(api, name):
                assert not hasattr(self, name)
                setattr(self, name, getattr(api, name))

    def call(self, executable, *args):
        """
        Call ``executable`` with ``args`` using subprocess.call().

        If the call exits with a non-zero exit status,
        `ipalib.errors.SubprocessError` is raised, from which you can retrieve
        the exit code by checking the SubprocessError.returncode attribute.

        This method does *not* return what ``executable`` sent to stdout... for
        that, use `Plugin.callread()`.
        """
        argv = (executable,) + args
        self.debug('Calling %r', argv)
        code = subprocess.call(argv)
        if code != 0:
            raise errors.SubprocessError(returncode=code, argv=argv)

    def __repr__(self):
        """
        Return 'module_name.class_name()' representation.

        This representation could be used to instantiate this Plugin
        instance given the appropriate environment.
        """
        return '%s.%s()' % (
            self.__class__.__module__,
            self.__class__.__name__
        )


class PluginProxy(SetProxy):
    """
    Allow access to only certain attributes on a `Plugin`.

    Think of a proxy as an agreement that "I will have at most these
    attributes". This is different from (although similar to) an interface,
    which can be thought of as an agreement that "I will have at least these
    attributes".
    """

    __slots__ = (
        '__base',
        '__target',
        '__name_attr',
        '__public__',
        'name',
        'doc',
    )

    def __init__(self, base, target, name_attr='name'):
        """
        :param base: A subclass of `Plugin`.
        :param target: An instance ``base`` or a subclass of ``base``.
        :param name_attr: The name of the attribute on ``target`` from which
            to derive ``self.name``.
        """
        if not inspect.isclass(base):
            raise TypeError(
                '`base` must be a class, got %r' % base
            )
        if not isinstance(target, base):
            raise ValueError(
                '`target` must be an instance of `base`, got %r' % target
            )
        self.__base = base
        self.__target = target
        self.__name_attr = name_attr
        self.__public__ = base.__public__
        self.name = getattr(target, name_attr)
        self.doc = target.doc
        assert type(self.__public__) is frozenset
        super(PluginProxy, self).__init__(self.__public__)

    def implements(self, arg):
        """
        Return True if plugin being proxied implements ``arg``.

        This method simply calls the corresponding `Plugin.implements`
        classmethod.

        Unlike `Plugin.implements`, this is not a classmethod as a
        `PluginProxy` can only implement anything as an instance.
        """
        return self.__base.implements(arg)

    def __clone__(self, name_attr):
        """
        Return a `PluginProxy` instance similar to this one.

        The new `PluginProxy` returned will be identical to this one except
        the proxy name might be derived from a different attribute on the
        target `Plugin`.  The same base and target will be used.
        """
        return self.__class__(self.__base, self.__target, name_attr)

    def __getitem__(self, key):
        """
        Return attribute named ``key`` on target `Plugin`.

        If this proxy allows access to an attribute named ``key``, that
        attribute will be returned.  If access is not allowed,
        KeyError will be raised.
        """
        if key in self.__public__:
            return getattr(self.__target, key)
        raise KeyError('no public attribute %s.%s' % (self.name, key))

    def __getattr__(self, name):
        """
        Return attribute named ``name`` on target `Plugin`.

        If this proxy allows access to an attribute named ``name``, that
        attribute will be returned.  If access is not allowed,
        AttributeError will be raised.
        """
        if name in self.__public__:
            return getattr(self.__target, name)
        raise AttributeError('no public attribute %s.%s' % (self.name, name))

    def __call__(self, *args, **kw):
        """
        Call target `Plugin` and return its return value.

        If `__call__` is not an attribute this proxy allows access to,
        KeyError is raised.
        """
        return self['__call__'](*args, **kw)

    def __repr__(self):
        """
        Return a Python expression that could create this instance.
        """
        return '%s(%s, %r)' % (
            self.__class__.__name__,
            self.__base.__name__,
            self.__target,
        )


class Registrar(DictProxy):
    """
    Collects plugin classes as they are registered.

    The Registrar does not instantiate plugins... it only implements the
    override logic and stores the plugins in a namespace per allowed base
    class.

    The plugins are instantiated when `API.finalize()` is called.
    """
    def __init__(self, *allowed):
        """
        :param allowed: Base classes from which plugins accepted by this
            Registrar must subclass.
        """
        self.__allowed = dict((base, {}) for base in allowed)
        self.__registered = set()
        super(Registrar, self).__init__(
            dict(self.__base_iter())
        )

    def __base_iter(self):
        for (base, sub_d) in self.__allowed.iteritems():
            assert inspect.isclass(base)
            name = base.__name__
            assert not hasattr(self, name)
            setattr(self, name, MagicDict(sub_d))
            yield (name, base)

    def __findbases(self, klass):
        """
        Iterates through allowed bases that ``klass`` is a subclass of.

        Raises `errors.PluginSubclassError` if ``klass`` is not a subclass of
        any allowed base.

        :param klass: The plugin class to find bases for.
        """
        assert inspect.isclass(klass)
        found = False
        for (base, sub_d) in self.__allowed.iteritems():
            if issubclass(klass, base):
                found = True
                yield (base, sub_d)
        if not found:
            raise errors.PluginSubclassError(
                plugin=klass, bases=self.__allowed.keys()
            )

    def __call__(self, klass, override=False):
        """
        Register the plugin ``klass``.

        :param klass: A subclass of `Plugin` to attempt to register.
        :param override: If true, override an already registered plugin.
        """
        if not inspect.isclass(klass):
            raise TypeError('plugin must be a class; got %r' % klass)

        # Raise DuplicateError if this exact class was already registered:
        if klass in self.__registered:
            raise errors.PluginDuplicateError(plugin=klass)

        # Find the base class or raise SubclassError:
        for (base, sub_d) in self.__findbases(klass):
            # Check override:
            if klass.__name__ in sub_d:
                if not override:
                    # Must use override=True to override:
                    raise errors.PluginOverrideError(
                        base=base.__name__,
                        name=klass.__name__,
                        plugin=klass,
                    )
            else:
                if override:
                    # There was nothing already registered to override:
                    raise errors.PluginMissingOverrideError(
                        base=base.__name__,
                        name=klass.__name__,
                        plugin=klass,
                    )

            # The plugin is okay, add to sub_d:
            sub_d[klass.__name__] = klass

        # The plugin is okay, add to __registered:
        self.__registered.add(klass)


class API(DictProxy):
    """
    Dynamic API object through which `Plugin` instances are accessed.
    """

    def __init__(self, *allowed):
        self.__d = dict()
        self.__done = set()
        self.register = Registrar(*allowed)
        self.env = Env()
        super(API, self).__init__(self.__d)

    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 environment variables and logging.
        """
        self.__doing('bootstrap')
        self.env._bootstrap(**overrides)
        self.env._finalize_core(**dict(DEFAULT_CONFIG))
        log = logging.getLogger()
        object.__setattr__(self, 'log', log)
        if self.env.debug:
            log.setLevel(logging.DEBUG)
        else:
            log.setLevel(logging.INFO)

        # Add stderr handler:
        stderr = logging.StreamHandler()
        if self.env.debug:
            stderr.setLevel(logging.DEBUG)
        elif self.env.verbose:
            stderr.setLevel(logging.INFO)
        else:
            stderr.setLevel(logging.WARNING)
        stderr.setFormatter(util.LogFormatter(FORMAT_STDERR))
        log.addHandler(stderr)

        # Add file handler:
        if self.env.mode in ('dummy', 'unit_test'):
            return  # But not if in unit-test mode
        if self.env.log is None:
            return
        log_dir = path.dirname(self.env.log)
        if not path.isdir(log_dir):
            try:
                os.makedirs(log_dir)
            except OSError:
                log.error('Could not create log_dir %r', log_dir)
                return
        try:
            handler = logging.FileHandler(self.env.log)
        except IOError, e:
            log.error('Cannot open log file %r: %s', self.env.log, e.strerror)
            return
        handler.setFormatter(util.LogFormatter(FORMAT_FILE))
        if self.env.debug:
            handler.setLevel(logging.DEBUG)
        else:
            handler.setLevel(logging.INFO)
        log.addHandler(handler)

    def build_global_parser(self, parser=None, context=None):
        """
        Add global options to an optparse.OptionParser instance.
        """
        if parser is None:
            parser = optparse.OptionParser()
            parser.disable_interspersed_args()
        parser.add_option('-e', dest='env', metavar='KEY=VAL', action='append',
            help='Set environment variable KEY to VAL',
        )
        parser.add_option('-c', dest='conf', metavar='FILE',
            help='Load configuration from FILE',
        )
        parser.add_option('-d', '--debug', action='store_true',
            help='Produce full debuging output',
        )
        parser.add_option('-v', '--verbose', action='store_true',
            help='Produce more verbose output',
        )
        if context == 'cli':
            parser.add_option('-a', '--prompt-all', action='store_true',
                help='Prompt for ALL values (even if optional)'
            )
            parser.add_option('-n', '--no-prompt', action='store_false',
                dest='interactive',
                help='Prompt for NO values (even if required)'
            )
        return parser

    def bootstrap_with_global_options(self, parser=None, context=None):
        parser = self.build_global_parser(parser, context)
        (options, args) = parser.parse_args()
        overrides = {}
        if options.env is not None:
            assert type(options.env) is list
            for item in options.env:
                try:
                    (key, value) = item.split('=', 1)
                except ValueError:
                    # FIXME: this should raise an IPA exception with an
                    # error code.
                    # --Jason, 2008-10-31
                    pass
                overrides[str(key.strip())] = value.strip()
        for key in ('conf', 'debug', 'verbose', 'prompt_all', 'interactive'):
            value = getattr(options, key, None)
            if value is not None:
                overrides[key] = value
        if context is not None:
            overrides['context'] = context
        self.bootstrap(**overrides)
        return args

    def load_plugins(self):
        """
        Load plugins from all standard locations.

        `API.bootstrap` will automatically be called if it hasn't been
        already.
        """
        self.__doing('load_plugins')
        self.__do_if_not_done('bootstrap')
        if self.env.mode in ('dummy', 'unit_test'):
            return
        self.import_plugins('ipalib')
        if self.env.in_server:
            self.import_plugins('ipaserver')

    # FIXME: This method has no unit test
    def import_plugins(self, package):
        """
        Import modules in ``plugins`` sub-package of ``package``.
        """
        subpackage = '%s.plugins' % package
        try:
            parent = __import__(package)
            plugins = __import__(subpackage).plugins
        except ImportError, e:
            self.log.error(
                'cannot import plugins sub-package %s: %s', subpackage, e
            )
            raise e
        parent_dir = path.dirname(path.abspath(parent.__file__))
        plugins_dir = path.dirname(path.abspath(plugins.__file__))
        if parent_dir == plugins_dir:
            raise errors.PluginsPackageError(
                name=subpackage, file=plugins.__file__
            )
        self.log.debug('importing all plugin modules in %r...', plugins_dir)
        for (name, pyfile) in util.find_modules_in_dir(plugins_dir):
            fullname = '%s.%s' % (subpackage, name)
            self.log.debug('importing plugin module %r', pyfile)
            try:
                __import__(fullname)
            except errors.SkipPluginModule, e:
                self.log.info(
                    'skipping plugin module %s: %s', fullname, e.reason
                )
            except StandardError, e:
                self.log.error('could not load plugin module %r', pyfile)
                raise e

    def finalize(self):
        """
        Finalize the registration, instantiate the plugins.

        `API.bootstrap` will automatically be called if it hasn't been
        already.
        """
        self.__doing('finalize')
        self.__do_if_not_done('load_plugins')

        class PluginInstance(object):
            """
            Represents a plugin instance.
            """

            i = 0

            def __init__(self, klass):
                self.created = self.next()
                self.klass = klass
                self.instance = klass()
                self.bases = []

            @classmethod
            def next(cls):
                cls.i += 1
                return cls.i

        class PluginInfo(ReadOnly):
            def __init__(self, p):
                assert isinstance(p, PluginInstance)
                self.created = p.created
                self.name = p.klass.__name__
                self.module = str(p.klass.__module__)
                self.plugin = '%s.%s' % (self.module, self.name)
                self.bases = tuple(b.__name__ for b in p.bases)
                lock(self)

        plugins = {}
        def plugin_iter(base, subclasses):
            for klass in subclasses:
                assert issubclass(klass, base)
                if klass not in plugins:
                    plugins[klass] = PluginInstance(klass)
                p = plugins[klass]
                assert base not in p.bases
                p.bases.append(base)
                if base.__proxy__:
                    yield PluginProxy(base, p.instance)
                else:
                    yield p.instance

        for name in self.register:
            base = self.register[name]
            magic = getattr(self.register, name)
            namespace = NameSpace(
                plugin_iter(base, (magic[k] for k in magic))
            )
            assert not (
                name in self.__d or hasattr(self, name)
            )
            self.__d[name] = namespace
            object.__setattr__(self, name, namespace)

        for p in plugins.itervalues():
            p.instance.set_api(self)
            assert p.instance.api is self

        for p in plugins.itervalues():
            p.instance.finalize()
            assert islocked(p.instance) is True
        object.__setattr__(self, '_API__finalized', True)
        tuple(PluginInfo(p) for p in plugins.itervalues())
        object.__setattr__(self, 'plugins',
            tuple(PluginInfo(p) for p in plugins.itervalues())
        )