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OpenStack Study: agent.py**** CubicPower OpenStack Study ****
# Copyright (c) 2010 Citrix Systems, Inc. # Copyright 2010-2012 OpenStack Foundation # # 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. import base64 import binascii from distutils import version import os import sys import time import uuid from oslo.config import cfg from nova.api.metadata import password from nova.compute import utils as compute_utils from nova import conductor from nova import context from nova import crypto from nova import exception from nova.openstack.common.gettextutils import _ from nova.openstack.common import jsonutils from nova.openstack.common import log as logging from nova.openstack.common import strutils from nova import utils USE_AGENT_KEY = "xenapi_use_agent" USE_AGENT_SM_KEY = utils.SM_IMAGE_PROP_PREFIX + USE_AGENT_KEY SKIP_SSH_KEY = "xenapi_skip_agent_inject_ssh" SKIP_SSH_SM_KEY = utils.SM_IMAGE_PROP_PREFIX + SKIP_SSH_KEY SKIP_FILES_AT_BOOT_KEY = "xenapi_skip_agent_inject_files_at_boot" SKIP_FILES_AT_BOOT_SM_KEY = utils.SM_IMAGE_PROP_PREFIX \ + SKIP_FILES_AT_BOOT_KEY LOG = logging.getLogger(__name__) xenapi_agent_opts = [ cfg.IntOpt('agent_timeout', default=30, deprecated_name='agent_timeout', deprecated_group='DEFAULT', help='Number of seconds to wait for agent reply'), cfg.IntOpt('agent_version_timeout', default=300, deprecated_name='agent_version_timeout', deprecated_group='DEFAULT', help='Number of seconds to wait for agent ' 'to be fully operational'), cfg.IntOpt('agent_resetnetwork_timeout', deprecated_name='agent_resetnetwork_timeout', deprecated_group='DEFAULT', default=60, help='Number of seconds to wait for agent reply ' 'to resetnetwork request'), cfg.StrOpt('agent_path', default='usr/sbin/xe-update-networking', deprecated_name='xenapi_agent_path', deprecated_group='DEFAULT', help='Specifies the path in which the XenAPI guest agent ' 'should be located. If the agent is present, network ' 'configuration is not injected into the image. ' 'Used if compute_driver=xenapi.XenAPIDriver and ' 'flat_injected=True'), cfg.BoolOpt('disable_agent', default=False, deprecated_name='xenapi_disable_agent', deprecated_group='DEFAULT', help='Disables the use of the XenAPI agent in any image ' 'regardless of what image properties are present.'), cfg.BoolOpt('use_agent_default', default=False, deprecated_name='xenapi_use_agent_default', deprecated_group='DEFAULT', help='Determines if the XenAPI agent should be used when ' 'the image used does not contain a hint to declare if ' 'the agent is present or not. ' 'The hint is a glance property "' + USE_AGENT_KEY + '" ' 'that has the value "True" or "False". ' 'Note that waiting for the agent when it is not present ' 'will significantly increase server boot times.'), ] CONF = cfg.CONF # xenapi_agent options in the DEFAULT group were deprecated in Icehouse CONF.register_opts(xenapi_agent_opts, 'xenserver')
**** CubicPower OpenStack Study **** def _call_agent(session, instance, vm_ref, method, addl_args=None, timeout=None, success_codes=None): """Abstracts out the interaction with the agent xenapi plugin.""" if addl_args is None: addl_args = {} if timeout is None: timeout = CONF.xenserver.agent_timeout if success_codes is None: success_codes = ['0'] # always fetch domid because VM may have rebooted dom_id = session.VM.get_domid(vm_ref) args = { 'id': str(uuid.uuid4()), 'dom_id': str(dom_id), 'timeout': str(timeout), } args.update(addl_args) try: ret = session.call_plugin('agent', method, args) except session.XenAPI.Failure as e: err_msg = e.details[-1].splitlines()[-1] if 'TIMEOUT:' in err_msg: LOG.error(_('TIMEOUT: The call to %(method)s timed out. ' 'args=%(args)r'), {'method': method, 'args': args}, instance=instance) raise exception.AgentTimeout(method=method) elif 'NOT IMPLEMENTED:' in err_msg: LOG.error(_('NOT IMPLEMENTED: The call to %(method)s is not ' 'supported by the agent. args=%(args)r'), {'method': method, 'args': args}, instance=instance) raise exception.AgentNotImplemented(method=method) else: LOG.error(_('The call to %(method)s returned an error: %(e)s. ' 'args=%(args)r'), {'method': method, 'args': args, 'e': e}, instance=instance) raise exception.AgentError(method=method) if not isinstance(ret, dict): try: ret = jsonutils.loads(ret) except TypeError: LOG.error(_('The agent call to %(method)s returned an invalid ' 'response: %(ret)r. args=%(args)r'), {'method': method, 'ret': ret, 'args': args}, instance=instance) raise exception.AgentError(method=method) if ret['returncode'] not in success_codes: LOG.error(_('The agent call to %(method)s returned an ' 'an error: %(ret)r. args=%(args)r'), {'method': method, 'ret': ret, 'args': args}, instance=instance) raise exception.AgentError(method=method) LOG.debug(_('The agent call to %(method)s was successful: ' '%(ret)r. args=%(args)r'), {'method': method, 'ret': ret, 'args': args}, instance=instance) # Some old versions of the Windows agent have a trailing \\r\\n # (ie CRLF escaped) for some reason. Strip that off. return ret['message'].replace('\\r\\n', '')
**** CubicPower OpenStack Study **** def is_upgrade_required(current_version, available_version): # NOTE(johngarbutt): agent version numbers are four part, # so we need to use the loose version to compare them current = version.LooseVersion(current_version) available = version.LooseVersion(available_version) return available > current
**** CubicPower OpenStack Study **** class XenAPIBasedAgent(object):
**** CubicPower OpenStack Study **** def __init__(self, session, virtapi, instance, vm_ref): self.session = session self.virtapi = virtapi self.instance = instance self.vm_ref = vm_ref
**** CubicPower OpenStack Study **** def _add_instance_fault(self, error, exc_info): LOG.warning(_("Ignoring error while configuring instance with " "agent: %s") % error, instance=self.instance, exc_info=True) try: ctxt = context.get_admin_context() capi = conductor.API() compute_utils.add_instance_fault_from_exc( ctxt, capi, self.instance, error, exc_info=exc_info) except Exception: pass
**** CubicPower OpenStack Study **** def _call_agent(self, method, addl_args=None, timeout=None, success_codes=None, ignore_errors=True): try: return _call_agent(self.session, self.instance, self.vm_ref, method, addl_args, timeout, success_codes) except exception.AgentError as error: if ignore_errors: self._add_instance_fault(error, sys.exc_info()) else: raise
**** CubicPower OpenStack Study **** def get_version(self): LOG.debug(_('Querying agent version'), instance=self.instance) # The agent can be slow to start for a variety of reasons. On Windows, # it will generally perform a setup process on first boot that can # take a couple of minutes and then reboot. On Linux, the system can # also take a while to boot. expiration = time.time() + CONF.xenserver.agent_version_timeout while True: try: # NOTE(johngarbutt): we can't use the xapi plugin # timeout, because the domid may change when # the server is rebooted return self._call_agent('version', ignore_errors=False) except exception.AgentError as error: if time.time() > expiration: self._add_instance_fault(error, sys.exc_info()) return
**** CubicPower OpenStack Study **** def _get_expected_build(self): ctxt = context.get_admin_context() agent_build = self.virtapi.agent_build_get_by_triple( ctxt, 'xen', self.instance['os_type'], self.instance['architecture']) if agent_build: LOG.debug(_('Latest agent build for %(hypervisor)s/%(os)s' '/%(architecture)s is %(version)s') % agent_build) else: LOG.debug(_('No agent build found for %(hypervisor)s/%(os)s' '/%(architecture)s') % { 'hypervisor': 'xen', 'os': self.instance['os_type'], 'architecture': self.instance['architecture']}) return agent_build
**** CubicPower OpenStack Study **** def update_if_needed(self, version): agent_build = self._get_expected_build() if version and agent_build and \ is_upgrade_required(version, agent_build['version']): LOG.debug(_('Updating agent to %s'), agent_build['version'], instance=self.instance) self._perform_update(agent_build) else: LOG.debug(_('Skipping agent update.'), instance=self.instance)
**** CubicPower OpenStack Study **** def _perform_update(self, agent_build): args = {'url': agent_build['url'], 'md5sum': agent_build['md5hash']} try: self._call_agent('agentupdate', args) except exception.AgentError as exc: # Silently fail for agent upgrades LOG.warning(_("Unable to update the agent due " "to: %(exc)s") % dict(exc=exc), instance=self.instance)
**** CubicPower OpenStack Study **** def _exchange_key_with_agent(self): dh = SimpleDH() args = {'pub': str(dh.get_public())} resp = self._call_agent('key_init', args, success_codes=['D0'], ignore_errors=False) agent_pub = int(resp) dh.compute_shared(agent_pub) return dh
**** CubicPower OpenStack Study **** def _save_instance_password_if_sshkey_present(self, new_pass): sshkey = self.instance.get('key_data') if sshkey and sshkey.startswith("ssh-rsa"): ctxt = context.get_admin_context() enc = crypto.ssh_encrypt_text(sshkey, new_pass) sys_meta = utils.instance_sys_meta(self.instance) sys_meta.update(password.convert_password(ctxt, base64.b64encode(enc))) self.virtapi.instance_update(ctxt, self.instance['uuid'], {'system_metadata': sys_meta})
**** CubicPower OpenStack Study **** def set_admin_password(self, new_pass): """Set the root/admin password on the VM instance. This is done via an agent running on the VM. Communication between nova and the agent is done via writing xenstore records. Since communication is done over the XenAPI RPC calls, we need to encrypt the password. We're using a simple Diffie-Hellman class instead of a more advanced library (such as M2Crypto) for compatibility with the agent code. """ LOG.debug(_('Setting admin password'), instance=self.instance) try: dh = self._exchange_key_with_agent() except exception.AgentError as error: self._add_instance_fault(error, sys.exc_info()) return # Some old versions of Linux and Windows agent expect trailing \n # on password to work correctly. enc_pass = dh.encrypt(new_pass + '\n') args = {'enc_pass': enc_pass} self._call_agent('password', args) self._save_instance_password_if_sshkey_present(new_pass)
**** CubicPower OpenStack Study **** def inject_ssh_key(self): sshkey = self.instance.get('key_data') if not sshkey: return if self.instance['os_type'] == 'windows': LOG.debug(_("Skipping setting of ssh key for Windows."), instance=self.instance) return if self._skip_ssh_key_inject(): LOG.debug(_("Skipping agent ssh key injection for this image."), instance=self.instance) return sshkey = str(sshkey) keyfile = '/root/.ssh/authorized_keys' key_data = ''.join([ '\n', '# The following ssh key was injected by Nova', '\n', sshkey.strip(), '\n', ]) return self.inject_file(keyfile, key_data)
**** CubicPower OpenStack Study **** def inject_files(self, injected_files): if self._skip_inject_files_at_boot(): LOG.debug(_("Skipping agent file injection for this image."), instance=self.instance) else: for path, contents in injected_files: self.inject_file(path, contents)
**** CubicPower OpenStack Study **** def inject_file(self, path, contents): LOG.debug(_('Injecting file path: %r'), path, instance=self.instance) # Files/paths must be base64-encoded for transmission to agent b64_path = base64.b64encode(path) b64_contents = base64.b64encode(contents) args = {'b64_path': b64_path, 'b64_contents': b64_contents} return self._call_agent('inject_file', args)
**** CubicPower OpenStack Study **** def resetnetwork(self): LOG.debug(_('Resetting network'), instance=self.instance) #NOTE(johngarbutt) old FreeBSD and Gentoo agents return 500 on success return self._call_agent('resetnetwork', timeout=CONF.xenserver.agent_resetnetwork_timeout, success_codes=['0', '500'])
**** CubicPower OpenStack Study **** def _skip_ssh_key_inject(self): return self._get_sys_meta_key(SKIP_SSH_SM_KEY)
**** CubicPower OpenStack Study **** def _skip_inject_files_at_boot(self): return self._get_sys_meta_key(SKIP_FILES_AT_BOOT_SM_KEY)
**** CubicPower OpenStack Study **** def _get_sys_meta_key(self, key): sys_meta = utils.instance_sys_meta(self.instance) raw_value = sys_meta.get(key, 'False') return strutils.bool_from_string(raw_value, strict=False) def find_guest_agent(base_dir): """tries to locate a guest agent at the path specified by agent_rel_path """ if CONF.xenserver.disable_agent: return False agent_rel_path = CONF.xenserver.agent_path agent_path = os.path.join(base_dir, agent_rel_path) if os.path.isfile(agent_path): # The presence of the guest agent # file indicates that this instance can # reconfigure the network from xenstore data, # so manipulation of files in /etc is not # required LOG.info(_('XenServer tools installed in this ' 'image are capable of network injection. ' 'Networking files will not be' 'manipulated')) return True xe_daemon_filename = os.path.join(base_dir, 'usr', 'sbin', 'xe-daemon') if os.path.isfile(xe_daemon_filename): LOG.info(_('XenServer tools are present ' 'in this image but are not capable ' 'of network injection')) else: LOG.info(_('XenServer tools are not ' 'installed in this image')) return False def should_use_agent(instance): sys_meta = utils.instance_sys_meta(instance) if USE_AGENT_SM_KEY not in sys_meta: return CONF.xenserver.use_agent_default else: use_agent_raw = sys_meta[USE_AGENT_SM_KEY] try: return strutils.bool_from_string(use_agent_raw, strict=True) except ValueError: LOG.warn(_("Invalid 'agent_present' value. " "Falling back to the default."), instance=instance) return CONF.xenserver.use_agent_default
**** CubicPower OpenStack Study **** def find_guest_agent(base_dir): """tries to locate a guest agent at the path specified by agent_rel_path """ if CONF.xenserver.disable_agent: return False agent_rel_path = CONF.xenserver.agent_path agent_path = os.path.join(base_dir, agent_rel_path) if os.path.isfile(agent_path): # The presence of the guest agent # file indicates that this instance can # reconfigure the network from xenstore data, # so manipulation of files in /etc is not # required LOG.info(_('XenServer tools installed in this ' 'image are capable of network injection. ' 'Networking files will not be' 'manipulated')) return True xe_daemon_filename = os.path.join(base_dir, 'usr', 'sbin', 'xe-daemon') if os.path.isfile(xe_daemon_filename): LOG.info(_('XenServer tools are present ' 'in this image but are not capable ' 'of network injection')) else: LOG.info(_('XenServer tools are not ' 'installed in this image')) return False
**** CubicPower OpenStack Study **** def should_use_agent(instance): sys_meta = utils.instance_sys_meta(instance) if USE_AGENT_SM_KEY not in sys_meta: return CONF.xenserver.use_agent_default else: use_agent_raw = sys_meta[USE_AGENT_SM_KEY] try: return strutils.bool_from_string(use_agent_raw, strict=True) except ValueError: LOG.warn(_("Invalid 'agent_present' value. " "Falling back to the default."), instance=instance) return CONF.xenserver.use_agent_default
**** CubicPower OpenStack Study **** class SimpleDH(object): """This class wraps all the functionality needed to implement basic Diffie-Hellman-Merkle key exchange in Python. It features intelligent
**** CubicPower OpenStack Study **** def __init__(self): self._prime = 162259276829213363391578010288127 self._base = 5 self._public = None self._shared = None self.generate_private()
**** CubicPower OpenStack Study **** def generate_private(self): self._private = int(binascii.hexlify(os.urandom(10)), 16) return self._private
**** CubicPower OpenStack Study **** def get_public(self): self._public = pow(self._base, self._private, self._prime) return self._public
**** CubicPower OpenStack Study **** def compute_shared(self, other): self._shared = pow(other, self._private, self._prime) return self._shared
**** CubicPower OpenStack Study **** def _run_ssl(self, text, decrypt=False): cmd = ['openssl', 'aes-128-cbc', '-A', '-a', '-pass', 'pass:%s' % self._shared, '-nosalt'] if decrypt: cmd.append('-d') out, err = utils.execute(*cmd, process_input=text) if err: raise RuntimeError(_('OpenSSL error: %s') % err) return out
**** CubicPower OpenStack Study **** def encrypt(self, text): return self._run_ssl(text).strip('\n')
**** CubicPower OpenStack Study **** def decrypt(self, text): return self._run_ssl(text, decrypt=True)
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