root / snf-cyclades-app / synnefo / logic / backend_allocator.py @ a633e247
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# Copyright 2011 GRNET S.A. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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# SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and documentation are
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# those of the authors and should not be interpreted as representing official
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# policies, either expressed or implied, of GRNET S.A.
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import logging |
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import datetime |
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from django.utils import importlib |
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from synnefo.settings import (BACKEND_ALLOCATOR_MODULE, BACKEND_REFRESH_MIN, |
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BACKEND_PER_USER, ARCHIPELAGO_BACKENDS, |
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DEFAULT_INSTANCE_NETWORKS) |
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from synnefo.db.models import Backend |
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from synnefo.logic.backend import update_resources |
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from synnefo.api.util import backend_public_networks |
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log = logging.getLogger(__name__) |
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class BackendAllocator(): |
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"""Wrapper class for instance allocation.
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"""
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def __init__(self): |
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self.strategy_mod =\
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importlib.import_module(BACKEND_ALLOCATOR_MODULE) |
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def allocate(self, userid, flavor): |
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"""Allocate a vm of the specified flavor to a backend.
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Warning!!: An explicit commit is required after calling this function,
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in order to release the locks acquired by the get_available_backends
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function.
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"""
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backend = None
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backend = get_backend_for_user(userid) |
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if backend:
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return backend
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# Get the size of the vm
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disk = flavor_disk(flavor) |
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ram = flavor.ram |
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cpu = flavor.cpu |
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vm = {'ram': ram, 'disk': disk, 'cpu': cpu} |
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log.debug("Allocating VM: %r", vm)
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# Get available backends
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available_backends = get_available_backends() |
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# Temporary fix for distinquishing archipelagos capable backends
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available_backends = filter_archipelagos_backends(available_backends, |
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flavor.disk_template) |
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# Refresh backends, if needed
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refresh_backends_stats(available_backends) |
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if not available_backends: |
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return None |
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# Find the best backend to host the vm, based on the allocation
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# strategy
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backend = self.strategy_mod.allocate(available_backends, vm)
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log.info("Allocated VM %r, in backend %s", vm, backend)
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# Reduce the free resources of the selected backend by the size of
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# the vm
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reduce_backend_resources(backend, vm) |
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return backend
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def get_available_backends(): |
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"""Get available backends from db.
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"""
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backends = list(Backend.objects.select_for_update().filter(drained=False, |
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offline=False))
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if "SNF:ANY_PUBLIC" in DEFAULT_INSTANCE_NETWORKS: |
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backends = filter(lambda x: has_free_ip(x), backends) |
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return backends
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def filter_archipelagos_backends(available_backends, disk_template): |
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if disk_template == "ext": |
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available_backends = filter(lambda x: x.id in ARCHIPELAGO_BACKENDS, |
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available_backends) |
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else:
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available_backends = filter(lambda x: x.id not in ARCHIPELAGO_BACKENDS, |
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available_backends) |
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return available_backends
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def has_free_ip(backend): |
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"""Find if Backend has any free public IP."""
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for network in backend_public_networks(backend): |
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if not network.get_pool().empty(): |
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return True |
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log.warning("No available network in backend %r", backend)
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return False |
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def flavor_disk(flavor): |
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""" Get flavor's 'real' disk size
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"""
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if flavor.disk_template == 'drbd': |
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return flavor.disk * 1024 * 2 |
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else:
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return flavor.disk * 1024 |
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def reduce_backend_resources(backend, vm): |
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""" Conservatively update the resources of a backend.
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Reduce the free resources of the backend by the size of the of the vm that
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will host. This is an underestimation of the backend capabilities.
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"""
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new_mfree = backend.mfree - vm['ram']
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new_dfree = backend.dfree - vm['disk']
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backend.mfree = 0 if new_mfree < 0 else new_mfree |
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backend.dfree = 0 if new_dfree < 0 else new_dfree |
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backend.pinst_cnt += 1
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backend.save() |
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def refresh_backends_stats(backends): |
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""" Refresh the statistics of the backends.
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Set db backend state to the actual state of the backend, if
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BACKEND_REFRESH_MIN time has passed.
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"""
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now = datetime.datetime.now() |
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delta = datetime.timedelta(minutes=BACKEND_REFRESH_MIN) |
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for b in backends: |
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if now > b.updated + delta:
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log.debug("Updating resources of backend %r. Last Updated %r",
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b, b.updated) |
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update_resources(b) |
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def get_backend_for_user(userid): |
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"""Find fixed Backend for user based on BACKEND_PER_USER setting."""
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backend = BACKEND_PER_USER.get(userid) |
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if not backend: |
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return None |
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try:
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try:
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backend_id = int(backend)
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return Backend.objects.get(id=backend_id)
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except ValueError: |
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pass
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backend_name = str(backend)
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return Backend.objects.get(clustername=backend_name)
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except Backend.DoesNotExist:
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log.error("Invalid backend %s for user %s", backend, userid)
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