This file is indexed.

/usr/lib/python2.7/dist-packages/etcd/client.py is in python-etcd 0.4.3-2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  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
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
"""
.. module:: python-etcd
   :synopsis: A python etcd client.

.. moduleauthor:: Jose Plana <jplana@gmail.com>


"""
import logging
try:
    # Python 3
    from http.client import HTTPException
except ImportError:
    # Python 2
    from httplib import HTTPException
import socket
import urllib3
import urllib3.util
import json
import ssl
import dns.resolver
from functools import wraps
import etcd

try:
    from urlparse import urlparse
except ImportError:
    from urllib.parse import urlparse


_log = logging.getLogger(__name__)


class Client(object):

    """
    Client for etcd, the distributed log service using raft.
    """

    _MGET = 'GET'
    _MPUT = 'PUT'
    _MPOST = 'POST'
    _MDELETE = 'DELETE'
    _comparison_conditions = set(('prevValue', 'prevIndex', 'prevExist'))
    _read_options = set(('recursive', 'wait', 'waitIndex', 'sorted', 'quorum'))
    _del_conditions = set(('prevValue', 'prevIndex'))

    http = None

    def __init__(
            self,
            host='127.0.0.1',
            port=4001,
            srv_domain=None,
            version_prefix='/v2',
            read_timeout=60,
            allow_redirect=True,
            protocol='http',
            cert=None,
            ca_cert=None,
            username=None,
            password=None,
            allow_reconnect=False,
            use_proxies=False,
            expected_cluster_id=None,
            per_host_pool_size=10
    ):
        """
        Initialize the client.

        Args:
            host (mixed):
                           If a string, IP to connect to.
                           If a tuple ((host, port), (host, port), ...)

            port (int):  Port used to connect to etcd.

            srv_domain (str): Domain to search the SRV record for cluster autodiscovery.

            version_prefix (str): Url or version prefix in etcd url (default=/v2).

            read_timeout (int):  max seconds to wait for a read.

            allow_redirect (bool): allow the client to connect to other nodes.

            protocol (str):  Protocol used to connect to etcd.

            cert (mixed):   If a string, the whole ssl client certificate;
                            if a tuple, the cert and key file names.

            ca_cert (str): The ca certificate. If pressent it will enable
                           validation.

            username (str): username for etcd authentication.

            password (str): password for etcd authentication.

            allow_reconnect (bool): allow the client to reconnect to another
                                    etcd server in the cluster in the case the
                                    default one does not respond.

            use_proxies (bool): we are using a list of proxies to which we connect,
                                 and don't want to connect to the original etcd cluster.

            expected_cluster_id (str): If a string, recorded as the expected
                                       UUID of the cluster (rather than
                                       learning it from the first request),
                                       reads will raise EtcdClusterIdChanged
                                       if they receive a response with a
                                       different cluster ID.
            per_host_pool_size (int): specifies maximum number of connections to pool
                                      by host. By default this will use up to 10
                                      connections.
        """

        # If a DNS record is provided, use it to get the hosts list
        if srv_domain is not None:
            try:
                host = self._discover(srv_domain)
            except Exception as e:
                _log.error("Could not discover the etcd hosts from %s: %s",
                           srv_domain, e)

        self._protocol = protocol

        def uri(protocol, host, port):
            return '%s://%s:%d' % (protocol, host, port)

        if not isinstance(host, tuple):
            self._machines_cache = []
            self._base_uri = uri(self._protocol, host, port)
        else:
            if not allow_reconnect:
                _log.error("List of hosts incompatible with allow_reconnect.")
                raise etcd.EtcdException("A list of hosts to connect to was given, but reconnection not allowed?")
            self._machines_cache = [uri(self._protocol, *conn) for conn in host]
            self._base_uri = self._machines_cache.pop(0)

        self.expected_cluster_id = expected_cluster_id
        self.version_prefix = version_prefix

        self._read_timeout = read_timeout
        self._allow_redirect = allow_redirect
        self._use_proxies = use_proxies
        self._allow_reconnect = allow_reconnect

        # SSL Client certificate support

        kw = {
          'maxsize': per_host_pool_size
        }

        if self._read_timeout > 0:
            kw['timeout'] = self._read_timeout

        if protocol == 'https':
            # If we don't allow TLSv1, clients using older version of OpenSSL
            # (<1.0) won't be able to connect.
            _log.debug("HTTPS enabled.")
            kw['ssl_version'] = ssl.PROTOCOL_TLSv1

        if cert:
            if isinstance(cert, tuple):
                # Key and cert are separate
                kw['cert_file'] = cert[0]
                kw['key_file'] = cert[1]
            else:
                # combined certificate
                kw['cert_file'] = cert

        if ca_cert:
            kw['ca_certs'] = ca_cert
            kw['cert_reqs'] = ssl.CERT_REQUIRED

        self.username = None
        self.password = None
        if username and password:
            self.username = username
            self.password = password
        elif username:
            _log.warning('Username provided without password, both are required for authentication')
        elif password:
            _log.warning('Password provided without username, both are required for authentication')

        self.http = urllib3.PoolManager(num_pools=10, **kw)

        _log.debug("New etcd client created for %s", self.base_uri)

        if self._allow_reconnect:
            # we need the set of servers in the cluster in order to try
            # reconnecting upon error. The cluster members will be
            # added to the hosts list you provided. If you are using
            # proxies, set all
            #
            # Beware though: if you input '127.0.0.1' as your host and
            # etcd advertises 'localhost', both will be in the
            # resulting list.

            # If we're connecting to the original cluster, we can
            # extend the list given to the client with what we get
            # from self.machines
            if not self._use_proxies:
                self._machines_cache = list(set(self._machines_cache) |
                                            set(self.machines))
            if self._base_uri in self._machines_cache:
                self._machines_cache.remove(self._base_uri)
            _log.debug("Machines cache initialised to %s",
                       self._machines_cache)

    def _discover(self, domain):
        srv_name = "_etcd._tcp.{}".format(domain)
        answers = dns.resolver.query(srv_name, 'SRV')
        hosts = []
        for answer in answers:
            hosts.append(
                (answer.target.to_text(omit_final_dot=True), answer.port))
        _log.debug("Found %s", hosts)
        if not len(hosts):
            raise ValueError("The SRV record is present but no host were found")
        return tuple(hosts)

    def __del__(self):
        """Clean up open connections"""
        if self.http is not None:
            try:
                self.http.clear()
            except ReferenceError:
                # this may hit an already-cleared weakref
                pass

    @property
    def base_uri(self):
        """URI used by the client to connect to etcd."""
        return self._base_uri

    @property
    def host(self):
        """Node to connect  etcd."""
        return urlparse(self._base_uri).netloc.split(':')[0]

    @property
    def port(self):
        """Port to connect etcd."""
        return int(urlparse(self._base_uri).netloc.split(':')[1])

    @property
    def protocol(self):
        """Protocol used to connect etcd."""
        return self._protocol

    @property
    def read_timeout(self):
        """Max seconds to wait for a read."""
        return self._read_timeout

    @property
    def allow_redirect(self):
        """Allow the client to connect to other nodes."""
        return self._allow_redirect

    @property
    def machines(self):
        """
        Members of the cluster.

        Returns:
            list. str with all the nodes in the cluster.

        >>> print client.machines
        ['http://127.0.0.1:4001', 'http://127.0.0.1:4002']
        """
        # We can't use api_execute here, or it causes a logical loop
        try:
            uri = self._base_uri + self.version_prefix + '/machines'
            response = self.http.request(
                self._MGET,
                uri,
                headers=self._get_headers(),
                timeout=self.read_timeout,
                redirect=self.allow_redirect)

            machines = [
                node.strip() for node in
                self._handle_server_response(response).data.decode('utf-8').split(',')
            ]
            _log.debug("Retrieved list of machines: %s", machines)
            return machines
        except (urllib3.exceptions.HTTPError,
                HTTPException,
                socket.error) as e:
            # We can't get the list of machines, if one server is in the
            # machines cache, try on it
            _log.error("Failed to get list of machines from %s%s: %r",
                       self._base_uri, self.version_prefix, e)
            if self._machines_cache:
                self._base_uri = self._machines_cache.pop(0)
                _log.info("Retrying on %s", self._base_uri)
                # Call myself
                return self.machines
            else:
                raise etcd.EtcdException("Could not get the list of servers, "
                                         "maybe you provided the wrong "
                                         "host(s) to connect to?")

    @property
    def members(self):
        """
        A more structured view of peers in the cluster.

        Note that while we have an internal DS called _members, accessing the public property will call etcd.
        """
        # Empty the members list
        self._members = {}
        try:
            data = self.api_execute(self.version_prefix + '/members',
                                    self._MGET).data.decode('utf-8')
            res = json.loads(data)
            for member in res['members']:
                self._members[member['id']] = member
            return self._members
        except:
            raise etcd.EtcdException("Could not get the members list, maybe the cluster has gone away?")

    @property
    def leader(self):
        """
        Returns:
            dict. the leader of the cluster.

        >>> print client.leader
        {"id":"ce2a822cea30bfca","name":"default","peerURLs":["http://localhost:2380","http://localhost:7001"],"clientURLs":["http://127.0.0.1:4001"]}
        """
        try:

            leader = json.loads(
                self.api_execute(self.version_prefix + '/stats/self',
                                 self._MGET).data.decode('utf-8'))
            return self.members[leader['leaderInfo']['leader']]
        except Exception as e:
            raise etcd.EtcdException("Cannot get leader data: %s" % e)

    @property
    def stats(self):
        """
        Returns:
            dict. the stats of the local server
        """
        return self._stats()

    @property
    def leader_stats(self):
        """
        Returns:
            dict. the stats of the leader
        """
        return self._stats('leader')

    @property
    def store_stats(self):
        """
        Returns:
           dict. the stats of the kv store
        """
        return self._stats('store')

    def _stats(self, what='self'):
        """ Internal method to access the stats endpoints"""
        data = self.api_execute(self.version_prefix
                                + '/stats/' + what, self._MGET).data.decode('utf-8')
        try:
            return json.loads(data)
        except (TypeError,ValueError):
            raise etcd.EtcdException("Cannot parse json data in the response")

    @property
    def key_endpoint(self):
        """
        REST key endpoint.
        """
        return self.version_prefix + '/keys'

    def __contains__(self, key):
        """
        Check if a key is available in the cluster.

        >>> print 'key' in client
        True
        """
        try:
            self.get(key)
            return True
        except etcd.EtcdKeyNotFound:
            return False

    def _sanitize_key(self, key):
        if not key.startswith('/'):
            key = "/{}".format(key)
        return key


    def write(self, key, value, ttl=None, dir=False, append=False, **kwdargs):
        """
        Writes the value for a key, possibly doing atomit Compare-and-Swap

        Args:
            key (str):  Key.

            value (object):  value to set

            ttl (int):  Time in seconds of expiration (optional).

            dir (bool): Set to true if we are writing a directory; default is false.

            append (bool): If true, it will post to append the new value to the dir, creating a sequential key. Defaults to false.

            Other parameters modifying the write method are accepted:


            prevValue (str): compare key to this value, and swap only if corresponding (optional).

            prevIndex (int): modify key only if actual modifiedIndex matches the provided one (optional).

            prevExist (bool): If false, only create key; if true, only update key.

        Returns:
            client.EtcdResult

        >>> print client.write('/key', 'newValue', ttl=60, prevExist=False).value
        'newValue'

        """
        _log.debug("Writing %s to key %s ttl=%s dir=%s append=%s",
                  value, key, ttl, dir, append)
        key = self._sanitize_key(key)
        params = {}
        if value is not None:
            params['value'] = value

        if ttl is not None:
            params['ttl'] = ttl

        if dir:
            if value:
                raise etcd.EtcdException(
                    'Cannot create a directory with a value')
            params['dir'] = "true"

        for (k, v) in kwdargs.items():
            if k in self._comparison_conditions:
                if type(v) == bool:
                    params[k] = v and "true" or "false"
                else:
                    params[k] = v

        method = append and self._MPOST or self._MPUT
        if '_endpoint' in kwdargs:
            path = kwdargs['_endpoint'] + key
        else:
            path = self.key_endpoint + key

        response = self.api_execute(path, method, params=params)
        return self._result_from_response(response)

    def update(self, obj):
        """
        Updates the value for a key atomically. Typical usage would be:

        c = etcd.Client()
        o = c.read("/somekey")
        o.value += 1
        c.update(o)

        Args:
            obj (etcd.EtcdResult):  The object that needs updating.

        """
        _log.debug("Updating %s to %s.", obj.key, obj.value)
        kwdargs = {
            'dir': obj.dir,
            'ttl': obj.ttl,
            'prevExist': True
            }

        if not obj.dir:
            # prevIndex on a dir causes a 'not a file' error. d'oh!
            kwdargs['prevIndex'] = obj.modifiedIndex
        return self.write(obj.key, obj.value, **kwdargs)

    def read(self, key, **kwdargs):
        """
        Returns the value of the key 'key'.

        Args:
            key (str):  Key.

            Recognized kwd args

            recursive (bool): If you should fetch recursively a dir

            wait (bool): If we should wait and return next time the key is changed

            waitIndex (int): The index to fetch results from.

            sorted (bool): Sort the output keys (alphanumerically)

            timeout (int):  max seconds to wait for a read.

        Returns:
            client.EtcdResult (or an array of client.EtcdResult if a
            subtree is queried)

        Raises:
            KeyValue:  If the key doesn't exists.

            urllib3.exceptions.TimeoutError: If timeout is reached.

        >>> print client.get('/key').value
        'value'

        """
        _log.debug("Issuing read for key %s with args %s", key, kwdargs)
        key = self._sanitize_key(key)

        params = {}
        for (k, v) in kwdargs.items():
            if k in self._read_options:
                if type(v) == bool:
                    params[k] = v and "true" or "false"
                elif v is not None:
                    params[k] = v

        timeout = kwdargs.get('timeout', None)

        response = self.api_execute(
            self.key_endpoint + key, self._MGET, params=params,
            timeout=timeout)
        return self._result_from_response(response)

    def delete(self, key, recursive=None, dir=None, **kwdargs):
        """
        Removed a key from etcd.

        Args:

            key (str):  Key.

            recursive (bool): if we want to recursively delete a directory, set
                              it to true

            dir (bool): if we want to delete a directory, set it to true

            prevValue (str): compare key to this value, and swap only if
                             corresponding (optional).

            prevIndex (int): modify key only if actual modifiedIndex matches the
                             provided one (optional).

        Returns:
            client.EtcdResult

        Raises:
            KeyValue:  If the key doesn't exists.

        >>> print client.delete('/key').key
        '/key'

        """
        _log.debug("Deleting %s recursive=%s dir=%s extra args=%s",
                   key, recursive, dir, kwdargs)
        key = self._sanitize_key(key)

        kwds = {}
        if recursive is not None:
            kwds['recursive'] = recursive and "true" or "false"
        if dir is not None:
            kwds['dir'] = dir and "true" or "false"

        for k in self._del_conditions:
            if k in kwdargs:
                kwds[k] = kwdargs[k]
        _log.debug("Calculated params = %s", kwds)

        response = self.api_execute(
            self.key_endpoint + key, self._MDELETE, params=kwds)
        return self._result_from_response(response)

    def pop(self, key, recursive=None, dir=None, **kwdargs):
        """
        Remove specified key from etcd and return the corresponding value.

        Args:

            key (str):  Key.

            recursive (bool): if we want to recursively delete a directory, set
                              it to true

            dir (bool): if we want to delete a directory, set it to true

            prevValue (str): compare key to this value, and swap only if
                             corresponding (optional).

            prevIndex (int): modify key only if actual modifiedIndex matches the
                             provided one (optional).

        Returns:
            client.EtcdResult

        Raises:
            KeyValue:  If the key doesn't exists.

        >>> print client.pop('/key').value
        'value'

        """
        return self.delete(key=key, recursive=recursive, dir=dir, **kwdargs)._prev_node

    # Higher-level methods on top of the basic primitives
    def test_and_set(self, key, value, prev_value, ttl=None):
        """
        Atomic test & set operation.
        It will check if the value of 'key' is 'prev_value',
        if the the check is correct will change the value for 'key' to 'value'
        if the the check is false an exception will be raised.

        Args:
            key (str):  Key.
            value (object):  value to set
            prev_value (object):  previous value.
            ttl (int):  Time in seconds of expiration (optional).

        Returns:
            client.EtcdResult

        Raises:
            ValueError: When the 'prev_value' is not the current value.

        >>> print client.test_and_set('/key', 'new', 'old', ttl=60).value
        'new'

        """
        return self.write(key, value, prevValue=prev_value, ttl=ttl)

    def set(self, key, value, ttl=None):
        """
        Compatibility: sets the value of the key 'key' to the value 'value'

        Args:
            key (str):  Key.
            value (object):  value to set
            ttl (int):  Time in seconds of expiration (optional).

        Returns:
            client.EtcdResult

        Raises:
           etcd.EtcdException: when something weird goes wrong.

        """
        return self.write(key, value, ttl=ttl)

    def get(self, key):
        """
        Returns the value of the key 'key'.

        Args:
            key (str):  Key.

        Returns:
            client.EtcdResult

        Raises:
            KeyError:  If the key doesn't exists.

        >>> print client.get('/key').value
        'value'

        """
        return self.read(key)

    def watch(self, key, index=None, timeout=None, recursive=None):
        """
        Blocks until a new event has been received, starting at index 'index'

        Args:
            key (str):  Key.

            index (int): Index to start from.

            timeout (int):  max seconds to wait for a read.

        Returns:
            client.EtcdResult

        Raises:
            KeyValue:  If the key doesn't exists.

            urllib3.exceptions.TimeoutError: If timeout is reached.

        >>> print client.watch('/key').value
        'value'

        """
        _log.debug("About to wait on key %s, index %s", key, index)
        if index:
            return self.read(key, wait=True, waitIndex=index, timeout=timeout,
                             recursive=recursive)
        else:
            return self.read(key, wait=True, timeout=timeout,
                             recursive=recursive)

    def eternal_watch(self, key, index=None, recursive=None):
        """
        Generator that will yield changes from a key.
        Note that this method will block forever until an event is generated.

        Args:
            key (str):  Key to subcribe to.
            index (int):  Index from where the changes will be received.

        Yields:
            client.EtcdResult

        >>> for event in client.eternal_watch('/subcription_key'):
        ...     print event.value
        ...
        value1
        value2

        """
        local_index = index
        while True:
            response = self.watch(key, index=local_index, timeout=0, recursive=recursive)
            local_index = response.modifiedIndex + 1
            yield response

    def get_lock(self, *args, **kwargs):
        raise NotImplementedError('Lock primitives were removed from etcd 2.0')

    @property
    def election(self):
        raise NotImplementedError('Election primitives were removed from etcd 2.0')

    def _result_from_response(self, response):
        """ Creates an EtcdResult from json dictionary """
        raw_response = response.data
        try:
            res = json.loads(raw_response.decode('utf-8'))
        except (TypeError, ValueError, UnicodeError) as e:
            raise etcd.EtcdException(
                'Server response was not valid JSON: %r' % e)
        try:
            r = etcd.EtcdResult(**res)
            if response.status == 201:
                r.newKey = True
            r.parse_headers(response)
            return r
        except Exception as e:
            raise etcd.EtcdException(
                'Unable to decode server response: %r' % e)

    def _next_server(self, cause=None):
        """ Selects the next server in the list, refreshes the server list. """
        _log.debug("Selection next machine in cache. Available machines: %s",
                   self._machines_cache)
        try:
            mach = self._machines_cache.pop()
        except IndexError:
            _log.error("Machines cache is empty, no machines to try.")
            raise etcd.EtcdConnectionFailed('No more machines in the cluster',
                                            cause=cause)
        else:
            _log.info("Selected new etcd server %s", mach)
            return mach

    def _wrap_request(payload):
        @wraps(payload)
        def wrapper(self, path, method, params=None, timeout=None):
            some_request_failed = False
            response = False

            if timeout is None:
                timeout = self.read_timeout

            if timeout == 0:
                timeout = None

            if not path.startswith('/'):
                raise ValueError('Path does not start with /')

            while not response:
                try:
                    response = payload(self, path, method,
                                       params=params, timeout=timeout)
                    # Check the cluster ID hasn't changed under us.  We use
                    # preload_content=False above so we can read the headers
                    # before we wait for the content of a watch.
                    self._check_cluster_id(response)
                    # Now force the data to be preloaded in order to trigger any
                    # IO-related errors in this method rather than when we try to
                    # access it later.
                    _ = response.data
                    # urllib3 doesn't wrap all httplib exceptions and earlier versions
                    # don't wrap socket errors either.
                except (urllib3.exceptions.HTTPError,
                        HTTPException, socket.error) as e:
                    if (isinstance(params, dict) and
                        params.get("wait") == "true" and
                        isinstance(e,
                                   urllib3.exceptions.ReadTimeoutError)):
                        _log.debug("Watch timed out.")
                        raise etcd.EtcdWatchTimedOut(
                            "Watch timed out: %r" % e,
                            cause=e
                        )
                    _log.error("Request to server %s failed: %r",
                               self._base_uri, e)
                    if self._allow_reconnect:
                        _log.info("Reconnection allowed, looking for another "
                                  "server.")
                        # _next_server() raises EtcdException if there are no
                        # machines left to try, breaking out of the loop.
                        self._base_uri = self._next_server(cause=e)
                        some_request_failed = True

                        # if exception is raised on _ = response.data
                        # the condition for while loop will be False
                        # but we should retry
                        response = False
                    else:
                        _log.debug("Reconnection disabled, giving up.")
                        raise etcd.EtcdConnectionFailed(
                            "Connection to etcd failed due to %r" % e,
                            cause=e
                        )
                except etcd.EtcdClusterIdChanged as e:
                    _log.warning(e)
                    raise
                except:
                    _log.exception("Unexpected request failure, re-raising.")
                    raise

                if some_request_failed:
                    if not self._use_proxies:
                        # The cluster may have changed since last invocation
                        self._machines_cache = self.machines
                    self._machines_cache.remove(self._base_uri)
            return self._handle_server_response(response)
        return wrapper

    @_wrap_request
    def api_execute(self, path, method, params=None, timeout=None):
        """ Executes the query. """
        url = self._base_uri + path

        if (method == self._MGET) or (method == self._MDELETE):
            return self.http.request(
                method,
                url,
                timeout=timeout,
                fields=params,
                redirect=self.allow_redirect,
                headers=self._get_headers(),
                preload_content=False)

        elif (method == self._MPUT) or (method == self._MPOST):
            return self.http.request_encode_body(
                method,
                url,
                fields=params,
                timeout=timeout,
                encode_multipart=False,
                redirect=self.allow_redirect,
                headers=self._get_headers(),
                preload_content=False)
        else:
                    raise etcd.EtcdException(
                        'HTTP method {} not supported'.format(method))

    @_wrap_request
    def api_execute_json(self, path, method, params=None, timeout=None):
        url = self._base_uri + path
        json_payload = json.dumps(params)
        headers = self._get_headers()
        headers['Content-Type'] = 'application/json'
        return self.http.urlopen(method,
                                 url,
                                 body=json_payload,
                                 timeout=timeout,
                                 redirect=self.allow_redirect,
                                 headers=headers,
                                 preload_content=False)

    def _check_cluster_id(self, response):
        cluster_id = response.getheader("x-etcd-cluster-id")
        if not cluster_id:
            _log.warning("etcd response did not contain a cluster ID")
            return
        id_changed = (self.expected_cluster_id and
                      cluster_id != self.expected_cluster_id)
        # Update the ID so we only raise the exception once.
        old_expected_cluster_id = self.expected_cluster_id
        self.expected_cluster_id = cluster_id
        if id_changed:
            # Defensive: clear the pool so that we connect afresh next
            # time.
            self.http.clear()
            raise etcd.EtcdClusterIdChanged(
                'The UUID of the cluster changed from {} to '
                '{}.'.format(old_expected_cluster_id, cluster_id))

    def _handle_server_response(self, response):
        """ Handles the server response """
        if response.status in [200, 201]:
            return response

        else:
            resp = response.data.decode('utf-8')

            # throw the appropriate exception
            try:
                r = json.loads(resp)
                r['status'] = response.status
            except (TypeError, ValueError):
                # Bad JSON, make a response locally.
                r = {"message": "Bad response",
                     "cause": str(resp)}
            etcd.EtcdError.handle(r)

    def _get_headers(self):
        if self.username and self.password:
            credentials = ':'.join((self.username, self.password))
            return urllib3.make_headers(basic_auth=credentials)
        return {}