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Viewing changes to ensemble/providers/ec2/connect.py

  • Committer: William Reade
  • Date: 2011-08-15 09:29:20 UTC
  • mfrom: (314.1.3 spike-catchup)
  • Revision ID: fwereade@gmail.com-20110815092920-amun4ufsutm7d938
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ensemble/providers/ec2/connect.py
 
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import datetime
 
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from datetime import timedelta
 
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from twisted.internet.defer import inlineCallbacks, returnValue
 
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from ensemble.errors import EnvironmentPending, NoConnection
 
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from ensemble.state.sshclient import SSHClient
 
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from .utils import log
 
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class EC2Connect(object):
 
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    def __init__(self, provider):
 
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        self._provider = provider
 
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    def run(self, share=False):
 
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        client_deferred = self._provider.get_zookeeper_machines()
 
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        client_deferred.addCallback(self._connect_to_machine, share)
 
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        client_deferred.addCallback(self._wait_for_initialization)
 
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        return client_deferred
 
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    def _connect_to_machine(self, machines, share):
 
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        # TODO Should we pick a random entry from the nodes list?
 
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        log.info("Connecting to environment.")
 
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        machine = machines[0]
 
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        if not machine.dns_name:
 
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            raise EnvironmentPending("machine %s has no address assigned yet"
 
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                                     % machine.instance_id)
 
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        client = SSHClient()
 
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        result = client.connect(machine.dns_name + ":2181",
 
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                                timeout=30, share=share)
 
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        result.addErrback(self._check_machine_age, machine)
 
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        return result
 
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    def _check_machine_age(self, failure, machine):
 
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        failure.trap(NoConnection)
 
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        five_minutes_ago = datetime.datetime.now() - timedelta(minutes=5)
 
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        if machine.launch_time > five_minutes_ago:
 
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            raise NoConnection("Can't yet connect to started machine: %s" %
 
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                               str(failure.value))
 
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        return failure
 
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    @inlineCallbacks
 
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    def _wait_for_initialization(self, client):
 
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        exists_d, watch_d = client.exists_and_watch("/initialized")
 
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        exists = yield exists_d
 
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        if not exists:
 
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            log.info("Environment still initializing.  Will wait.")
 
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            yield watch_d
 
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        else:
 
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            log.debug("Environment already initialized.")
 
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        returnValue(client)