root / snf-cyclades-app / synnefo / logic / backend_allocator.py @ e8aa2f64
History | View | Annotate | Download (6.2 kB)
1 |
# Copyright 2011 GRNET S.A. All rights reserved.
|
---|---|
2 |
#
|
3 |
# Redistribution and use in source and binary forms, with or without
|
4 |
# modification, are permitted provided that the following conditions
|
5 |
# are met:
|
6 |
#
|
7 |
# 1. Redistributions of source code must retain the above copyright
|
8 |
# notice, this list of conditions and the following disclaimer.
|
9 |
#
|
10 |
# 2. Redistributions in binary form must reproduce the above copyright
|
11 |
# notice, this list of conditions and the following disclaimer in the
|
12 |
# documentation and/or other materials provided with the distribution.
|
13 |
#
|
14 |
# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
15 |
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
16 |
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
17 |
# ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
18 |
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
19 |
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
20 |
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
21 |
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
22 |
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
23 |
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
24 |
# SUCH DAMAGE.
|
25 |
#
|
26 |
# The views and conclusions contained in the software and documentation are
|
27 |
# those of the authors and should not be interpreted as representing official
|
28 |
# policies, either expressed or implied, of GRNET S.A.
|
29 |
|
30 |
import logging |
31 |
import datetime |
32 |
from django.utils import importlib |
33 |
|
34 |
from synnefo.settings import (BACKEND_ALLOCATOR_MODULE, BACKEND_REFRESH_MIN, |
35 |
BACKEND_PER_USER, ARCHIPELAGO_BACKENDS) |
36 |
from synnefo.db.models import Backend |
37 |
from synnefo.logic.backend import update_resources |
38 |
from synnefo.api.util import backend_public_networks |
39 |
|
40 |
log = logging.getLogger(__name__) |
41 |
|
42 |
|
43 |
class BackendAllocator(): |
44 |
"""Wrapper class for instance allocation.
|
45 |
|
46 |
"""
|
47 |
def __init__(self): |
48 |
self.strategy_mod =\
|
49 |
importlib.import_module(BACKEND_ALLOCATOR_MODULE) |
50 |
|
51 |
def allocate(self, userid, flavor): |
52 |
"""Allocate a vm of the specified flavor to a backend.
|
53 |
|
54 |
Warning!!: An explicit commit is required after calling this function,
|
55 |
in order to release the locks acquired by the get_available_backends
|
56 |
function.
|
57 |
|
58 |
"""
|
59 |
|
60 |
backend = None
|
61 |
backend = get_backend_for_user(userid) |
62 |
if backend:
|
63 |
return backend
|
64 |
|
65 |
# Get the size of the vm
|
66 |
disk = flavor_disk(flavor) |
67 |
ram = flavor.ram |
68 |
cpu = flavor.cpu |
69 |
vm = {'ram': ram, 'disk': disk, 'cpu': cpu} |
70 |
|
71 |
log.debug("Allocating VM: %r", vm)
|
72 |
|
73 |
# Get available backends
|
74 |
available_backends = get_available_backends() |
75 |
|
76 |
# Temporary fix for distinquishing archipelagos capable backends
|
77 |
available_backends = filter_archipelagos_backends(available_backends, |
78 |
flavor.disk_template) |
79 |
# Refresh backends, if needed
|
80 |
refresh_backends_stats(available_backends) |
81 |
|
82 |
if not available_backends: |
83 |
return None |
84 |
|
85 |
# Find the best backend to host the vm, based on the allocation
|
86 |
# strategy
|
87 |
backend = self.strategy_mod.allocate(available_backends, vm)
|
88 |
|
89 |
log.info("Allocated VM %r, in backend %s", vm, backend)
|
90 |
|
91 |
# Reduce the free resources of the selected backend by the size of
|
92 |
# the vm
|
93 |
reduce_backend_resources(backend, vm) |
94 |
|
95 |
return backend
|
96 |
|
97 |
|
98 |
def get_available_backends(): |
99 |
"""Get available backends from db.
|
100 |
|
101 |
"""
|
102 |
backends = list(Backend.objects.select_for_update().filter(drained=False, |
103 |
offline=False))
|
104 |
return filter(lambda x: has_free_ip(x), backends) |
105 |
|
106 |
|
107 |
def filter_archipelagos_backends(available_backends, disk_template): |
108 |
if disk_template == "ext": |
109 |
available_backends = filter(lambda x: x.id in ARCHIPELAGO_BACKENDS, |
110 |
available_backends) |
111 |
else:
|
112 |
available_backends = filter(lambda x: x.id not in ARCHIPELAGO_BACKENDS, |
113 |
available_backends) |
114 |
return available_backends
|
115 |
|
116 |
|
117 |
def has_free_ip(backend): |
118 |
"""Find if Backend has any free public IP."""
|
119 |
for network in backend_public_networks(backend): |
120 |
if not network.get_pool().empty(): |
121 |
return True |
122 |
log.warning("No available network in backend %r", backend)
|
123 |
return False |
124 |
|
125 |
|
126 |
def flavor_disk(flavor): |
127 |
""" Get flavor's 'real' disk size
|
128 |
|
129 |
"""
|
130 |
if flavor.disk_template == 'drbd': |
131 |
return flavor.disk * 1024 * 2 |
132 |
else:
|
133 |
return flavor.disk * 1024 |
134 |
|
135 |
|
136 |
def reduce_backend_resources(backend, vm): |
137 |
""" Conservatively update the resources of a backend.
|
138 |
|
139 |
Reduce the free resources of the backend by the size of the of the vm that
|
140 |
will host. This is an underestimation of the backend capabilities.
|
141 |
|
142 |
"""
|
143 |
|
144 |
new_mfree = backend.mfree - vm['ram']
|
145 |
new_dfree = backend.dfree - vm['disk']
|
146 |
backend.mfree = 0 if new_mfree < 0 else new_mfree |
147 |
backend.dfree = 0 if new_dfree < 0 else new_dfree |
148 |
backend.pinst_cnt += 1
|
149 |
|
150 |
backend.save() |
151 |
|
152 |
|
153 |
def refresh_backends_stats(backends): |
154 |
""" Refresh the statistics of the backends.
|
155 |
|
156 |
Set db backend state to the actual state of the backend, if
|
157 |
BACKEND_REFRESH_MIN time has passed.
|
158 |
|
159 |
"""
|
160 |
|
161 |
now = datetime.datetime.now() |
162 |
delta = datetime.timedelta(minutes=BACKEND_REFRESH_MIN) |
163 |
for b in backends: |
164 |
if now > b.updated + delta:
|
165 |
log.debug("Updating resources of backend %r. Last Updated %r",
|
166 |
b, b.updated) |
167 |
update_resources(b) |
168 |
|
169 |
|
170 |
def get_backend_for_user(userid): |
171 |
"""Find fixed Backend for user based on BACKEND_PER_USER setting."""
|
172 |
|
173 |
backend = BACKEND_PER_USER.get(userid) |
174 |
|
175 |
if not backend: |
176 |
return None |
177 |
|
178 |
try:
|
179 |
try:
|
180 |
backend_id = int(backend)
|
181 |
return Backend.objects.get(id=backend_id)
|
182 |
except ValueError: |
183 |
pass
|
184 |
|
185 |
backend_name = str(backend)
|
186 |
return Backend.objects.get(clustername=backend_name)
|
187 |
except Backend.DoesNotExist:
|
188 |
log.error("Invalid backend %s for user %s", backend, userid)
|