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# Microsoft Azure Linux Agent
#
# Copyright 2018 Microsoft Corporation
#
# 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.
#
# Requires Python 2.6+ and Openssl 1.0+
#
import re
import os
import socket
import time
import threading
import datetime
import azurelinuxagent.common.conf as conf
import azurelinuxagent.common.logger as logger
from azurelinuxagent.common.dhcp import get_dhcp_handler
from azurelinuxagent.common.event import add_periodic, WALAEventOperation
from azurelinuxagent.common.future import ustr
from azurelinuxagent.common.osutil import get_osutil
from azurelinuxagent.common.protocol import get_protocol_util
from azurelinuxagent.common.utils.archive import StateArchiver
from azurelinuxagent.common.version import AGENT_NAME, CURRENT_VERSION
CACHE_PATTERNS = [
re.compile("^(.*)\.(\d+)\.(agentsManifest)$", re.IGNORECASE),
re.compile("^(.*)\.(\d+)\.(manifest\.xml)$", re.IGNORECASE),
re.compile("^(.*)\.(\d+)\.(xml)$", re.IGNORECASE)
]
MAXIMUM_CACHED_FILES = 50
ARCHIVE_INTERVAL = datetime.timedelta(hours=24)
def get_env_handler():
return EnvHandler()
class EnvHandler(object):
"""
Monitor changes to dhcp and hostname.
If dhcp client process re-start has occurred, reset routes, dhcp with fabric.
Monitor scsi disk.
If new scsi disk found, set timeout
"""
def __init__(self):
self.osutil = get_osutil()
self.dhcp_handler = get_dhcp_handler()
self.protocol_util = get_protocol_util()
self.stopped = True
self.hostname = None
self.dhcp_id_list = []
self.server_thread = None
self.dhcp_warning_enabled = True
self.last_archive = None
self.archiver = StateArchiver(conf.get_lib_dir())
def run(self):
if not self.stopped:
logger.info("Stop existing env monitor service.")
self.stop()
self.stopped = False
logger.info("Start env monitor service.")
self.dhcp_handler.conf_routes()
self.hostname = self.osutil.get_hostname_record()
self.dhcp_id_list = self.get_dhcp_client_pid()
self.start()
def is_alive(self):
return self.server_thread.is_alive()
def start(self):
self.server_thread = threading.Thread(target=self.monitor)
self.server_thread.setDaemon(True)
self.server_thread.setName("EnvHandler")
self.server_thread.start()
def monitor(self):
"""
Monitor firewall rules
Monitor dhcp client pid and hostname.
If dhcp client process re-start has occurred, reset routes.
Purge unnecessary files from disk cache.
"""
protocol = self.protocol_util.get_protocol()
reset_firewall_fules = False
while not self.stopped:
self.osutil.remove_rules_files()
if conf.enable_firewall():
# If the rules ever change we must reset all rules and start over again.
#
# There was a rule change at 2.2.26, which started dropping non-root traffic
# to WireServer. The previous rules allowed traffic. Having both rules in
# place negated the fix in 2.2.26.
if not reset_firewall_fules:
self.osutil.remove_firewall(dst_ip=protocol.endpoint, uid=os.getuid())
reset_firewall_fules = True
success = self.osutil.enable_firewall(dst_ip=protocol.endpoint, uid=os.getuid())
add_periodic(
logger.EVERY_HOUR,
AGENT_NAME,
version=CURRENT_VERSION,
op=WALAEventOperation.Firewall,
is_success=success,
log_event=False)
timeout = conf.get_root_device_scsi_timeout()
if timeout is not None:
self.osutil.set_scsi_disks_timeout(timeout)
if conf.get_monitor_hostname():
self.handle_hostname_update()
self.handle_dhclient_restart()
self.archive_history()
time.sleep(5)
def handle_hostname_update(self):
curr_hostname = socket.gethostname()
if curr_hostname != self.hostname:
logger.info("EnvMonitor: Detected hostname change: {0} -> {1}",
self.hostname,
curr_hostname)
self.osutil.set_hostname(curr_hostname)
self.osutil.publish_hostname(curr_hostname)
self.hostname = curr_hostname
def get_dhcp_client_pid(self):
pid = []
try:
# return a sorted list since handle_dhclient_restart needs to compare the previous value with
# the new value and the comparison should not be affected by the order of the items in the list
pid = sorted(self.osutil.get_dhcp_pid())
if len(pid) == 0 and self.dhcp_warning_enabled:
logger.warn("Dhcp client is not running.")
except Exception as exception:
if self.dhcp_warning_enabled:
logger.error("Failed to get the PID of the DHCP client: {0}", ustr(exception))
self.dhcp_warning_enabled = len(pid) != 0
return pid
def handle_dhclient_restart(self):
if len(self.dhcp_id_list) == 0:
self.dhcp_id_list = self.get_dhcp_client_pid()
return
if all(self.osutil.check_pid_alive(pid) for pid in self.dhcp_id_list):
return
new_pid = self.get_dhcp_client_pid()
if len(new_pid) != 0 and new_pid != self.dhcp_id_list:
logger.info("EnvMonitor: Detected dhcp client restart. Restoring routing table.")
self.dhcp_handler.conf_routes()
self.dhcp_id_list = new_pid
def archive_history(self):
"""
Purge history if we have exceed the maximum count.
Create a .zip of the history that has been preserved.
"""
if self.last_archive is not None \
and datetime.datetime.utcnow() < \
self.last_archive + ARCHIVE_INTERVAL:
return
self.archiver.purge()
self.archiver.archive()
def stop(self):
"""
Stop server communication and join the thread to main thread.
"""
self.stopped = True
if self.server_thread is not None:
self.server_thread.join()