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# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright 2011 Justin Santa Barbara
# Copyright 2014 Red Hat, Inc.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Utilities related to SSH connection management."""
import os
from eventlet import pools
from oslo_config import cfg
from oslo_log import log as logging
from oslo_utils import excutils
try:
import paramiko
except ImportError:
paramiko = None
from cinder import exception
from cinder.i18n import _
LOG = logging.getLogger(__name__)
ssh_opts = [
cfg.BoolOpt('strict_ssh_host_key_policy',
default=False,
help='Option to enable strict host key checking. When '
'set to "True" Cinder will only connect to systems '
'with a host key present in the configured '
'"ssh_hosts_key_file". When set to "False" the host key '
'will be saved upon first connection and used for '
'subsequent connections. Default=False'),
cfg.StrOpt('ssh_hosts_key_file',
default='$state_path/ssh_known_hosts',
help='File containing SSH host keys for the systems with which '
'Cinder needs to communicate. OPTIONAL: '
'Default=$state_path/ssh_known_hosts'),
]
CONF = cfg.CONF
CONF.register_opts(ssh_opts)
class SSHPool(pools.Pool):
"""A simple eventlet pool to hold ssh connections."""
def __init__(self, ip, port, conn_timeout, login, password=None,
privatekey=None, *args, **kwargs):
self.ip = ip
self.port = port
self.login = login
self.password = password
self.conn_timeout = conn_timeout if conn_timeout else None
self.privatekey = privatekey
self.hosts_key_file = None
self.current_size = 0
if paramiko is None:
raise exception.RequirementMissing(req='paramiko')
# Validate good config setting here.
# Paramiko handles the case where the file is inaccessible.
if not CONF.ssh_hosts_key_file:
raise exception.ParameterNotFound(param='ssh_hosts_key_file')
elif not os.path.isfile(CONF.ssh_hosts_key_file):
# If using the default path, just create the file.
if CONF.state_path in CONF.ssh_hosts_key_file:
open(CONF.ssh_hosts_key_file, 'a').close()
else:
msg = (_("Unable to find ssh_hosts_key_file: %s") %
CONF.ssh_hosts_key_file)
raise exception.InvalidInput(reason=msg)
if 'hosts_key_file' in kwargs.keys():
self.hosts_key_file = kwargs.pop('hosts_key_file')
LOG.info("Secondary ssh hosts key file %(kwargs)s will be "
"loaded along with %(conf)s from /etc/cinder.conf.",
{'kwargs': self.hosts_key_file,
'conf': CONF.ssh_hosts_key_file})
LOG.debug("Setting strict_ssh_host_key_policy to '%(policy)s' "
"using ssh_hosts_key_file '%(key_file)s'.",
{'policy': CONF.strict_ssh_host_key_policy,
'key_file': CONF.ssh_hosts_key_file})
self.strict_ssh_host_key_policy = CONF.strict_ssh_host_key_policy
if not self.hosts_key_file:
self.hosts_key_file = CONF.ssh_hosts_key_file
else:
self.hosts_key_file += ',' + CONF.ssh_hosts_key_file
super(SSHPool, self).__init__(*args, **kwargs)
def __del__(self):
# just return if nothing todo
if not self.current_size:
return
# change the size of the pool to reduce the number
# of elements on the pool via puts.
self.resize(1)
# release all but the last connection using
# get and put to allow any get waiters to complete.
while(self.waiting() or self.current_size > 1):
conn = self.get()
self.put(conn)
# Now free everthing that is left
while(self.free_items):
self.free_items.popleft().close()
self.current_size -= 1
def create(self):
try:
ssh = paramiko.SSHClient()
if ',' in self.hosts_key_file:
files = self.hosts_key_file.split(',')
for f in files:
ssh.load_host_keys(f)
else:
ssh.load_host_keys(self.hosts_key_file)
# If strict_ssh_host_key_policy is set we want to reject, by
# default if there is not entry in the known_hosts file.
# Otherwise we use AutoAddPolicy which accepts on the first
# Connect but fails if the keys change. load_host_keys can
# handle hashed known_host entries.
if self.strict_ssh_host_key_policy:
ssh.set_missing_host_key_policy(paramiko.RejectPolicy())
else:
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
if self.password:
ssh.connect(self.ip,
port=self.port,
username=self.login,
password=self.password,
timeout=self.conn_timeout)
elif self.privatekey:
pkfile = os.path.expanduser(self.privatekey)
privatekey = paramiko.RSAKey.from_private_key_file(pkfile)
ssh.connect(self.ip,
port=self.port,
username=self.login,
pkey=privatekey,
timeout=self.conn_timeout)
else:
msg = _("Specify a password or private_key")
raise exception.CinderException(msg)
if self.conn_timeout:
transport = ssh.get_transport()
transport.set_keepalive(self.conn_timeout)
return ssh
except Exception as e:
msg = _("Error connecting via ssh: %s") % str(e)
LOG.error(msg)
raise paramiko.SSHException(msg)
def get(self):
"""Return an item from the pool, when one is available.
This may cause the calling greenthread to block. Check if a
connection is active before returning it.
For dead connections create and return a new connection.
"""
conn = super(SSHPool, self).get()
if conn:
if conn.get_transport().is_active():
return conn
else:
conn.close()
try:
new_conn = self.create()
except Exception:
LOG.error("Create new item in SSHPool failed.")
with excutils.save_and_reraise_exception():
if conn:
self.current_size -= 1
return new_conn
def put(self, conn):
# If we are have more connections than we should just close it
if self.current_size > self.max_size:
conn.close()
self.current_size -= 1
return
super(SSHPool, self).put(conn)
def remove(self, ssh):
"""Close an ssh client and remove it from free_items."""
ssh.close()
if ssh in self.free_items:
self.free_items.remove(ssh)
if self.current_size > 0:
self.current_size -= 1
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