Merge pull request #292 from zdc/T1350

keepalived: T1350: Replaced transition scripts logic

1 files changed, 190 insertions, 0 deletions

diff --git a/src/system/keepalived-fifo.py b/src/system/keepalived-fifo.py
new file mode 100755
index 000000000..5e85da4a4
--- /dev/null
+++ b/src/system/keepalived-fifo.py
@@ -0,0 +1,190 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2020 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import os
+import time
+import signal
+import argparse
+import threading
+import subprocess
+import re
+import json
+from pathlib import Path
+from queue import Queue
+import logging
+from logging.handlers import SysLogHandler
+
+# configure logging
+logger = logging.getLogger(__name__)
+logs_format = logging.Formatter('%(filename)s: %(message)s')
+logs_handler_syslog = SysLogHandler('/dev/log')
+logs_handler_syslog.setFormatter(logs_format)
+logger.addHandler(logs_handler_syslog)
+logger.setLevel(logging.DEBUG)
+
+
+# class for all operations
+class KeepalivedFifo:
+    # init - read command arguments
+    def __init__(self):
+        logger.info("Starting FIFO pipe for Keepalived")
+        # define program arguments
+        cmd_args_parser = argparse.ArgumentParser(description='Create FIFO pipe for keepalived and process notify events', add_help=False)
+        cmd_args_parser.add_argument('PIPE', help='path to the FIFO pipe')
+        # parse arguments
+        cmd_args = cmd_args_parser.parse_args()
+        self._config_load()
+        self.pipe_path = cmd_args.PIPE
+
+        # create queue for messages and events for syncronization
+        self.message_queue = Queue(maxsize=100)
+        self.stopme = threading.Event()
+        self.message_event = threading.Event()
+
+    # load configuration
+    def _config_load(self):
+        try:
+            # read the dictionary file with configuration
+            with open('/run/keepalived_config.dict', 'r') as dict_file:
+                vrrp_config_dict = json.load(dict_file)
+            self.vrrp_config = {'vrrp_groups': {}, 'sync_groups': {}}
+            # save VRRP instances to the new dictionary
+            for vrrp_group in vrrp_config_dict['vrrp_groups']:
+                self.vrrp_config['vrrp_groups'][vrrp_group['name']] = {
+                    'STOP': vrrp_group.get('stop_script'),
+                    'FAULT': vrrp_group.get('fault_script'),
+                    'BACKUP': vrrp_group.get('backup_script'),
+                    'MASTER': vrrp_group.get('master_script')
+                }
+            # save VRRP sync groups to the new dictionary
+            for sync_group in vrrp_config_dict['sync_groups']:
+                self.vrrp_config['sync_groups'][sync_group['name']] = {
+                    'STOP': sync_group.get('stop_script'),
+                    'FAULT': sync_group.get('fault_script'),
+                    'BACKUP': sync_group.get('backup_script'),
+                    'MASTER': sync_group.get('master_script')
+                }
+            logger.debug("Loaded configuration: {}".format(self.vrrp_config))
+        except Exception as err:
+            logger.error("Unable to load configuration: {}".format(err))
+
+    # run command
+    def _run_command(self, command):
+        try:
+            logger.debug("Running the command: {}".format(command))
+            process = subprocess.Popen(command.split(' '), stdout=subprocess.PIPE, stdin=subprocess.PIPE, universal_newlines=True)
+            stdout, stderr = process.communicate()
+            if process.returncode != 0:
+                raise Exception("The command \"{}\" returned status {}. Error: {}".format(command, process.returncode, stderr))
+        except Exception as err:
+            logger.error("Unable to execute command \"{}\": {}".format(command, err))
+
+    # create FIFO pipe
+    def pipe_create(self):
+        if Path(self.pipe_path).exists():
+            logger.info("PIPE already exist: {}".format(self.pipe_path))
+        else:
+            os.mkfifo(self.pipe_path)
+
+    # process message from pipe
+    def pipe_process(self):
+        logger.debug("Message processing start")
+        regex_notify = re.compile(r'^(?P<type>\w+) "(?P<name>[\w-]+)" (?P<state>\w+) (?P<priority>\d+)$', re.MULTILINE)
+        while self.stopme.is_set() is False:
+            # wait for a new message event from pipe_wait
+            self.message_event.wait()
+            try:
+                # clear mesage event flag
+                self.message_event.clear()
+                # get all messages from queue and try to process them
+                while self.message_queue.empty() is not True:
+                    message = self.message_queue.get()
+                    logger.debug("Received message: {}".format(message))
+                    notify_message = regex_notify.search(message)
+                    # try to process a message if it looks valid
+                    if notify_message:
+                        n_type = notify_message.group('type')
+                        n_name = notify_message.group('name')
+                        n_state = notify_message.group('state')
+                        logger.info("{} {} changed state to {}".format(n_type, n_name, n_state))
+                        # check and run commands for VRRP instances
+                        if n_type == 'INSTANCE':
+                            if n_name in self.vrrp_config['vrrp_groups'] and n_state in self.vrrp_config['vrrp_groups'][n_name]:
+                                n_script = self.vrrp_config['vrrp_groups'][n_name].get(n_state)
+                                if n_script:
+                                    self._run_command(n_script)
+                        # check and run commands for VRRP sync groups
+                        # currently, this is not available in VyOS CLI
+                        if n_type == 'GROUP':
+                            if n_name in self.vrrp_config['sync_groups'] and n_state in self.vrrp_config['sync_groups'][n_name]:
+                                n_script = self.vrrp_config['sync_groups'][n_name].get(n_state)
+                                if n_script:
+                                    self._run_command(n_script)
+                    # mark task in queue as done
+                    self.message_queue.task_done()
+            except Exception as err:
+                logger.error("Error processing message: {}".format(err))
+        logger.debug("Terminating messages processing thread")
+
+    # wait for messages
+    def pipe_wait(self):
+        logger.debug("Message reading start")
+        self.pipe_read = os.open(self.pipe_path, os.O_RDONLY | os.O_NONBLOCK)
+        while self.stopme.is_set() is False:
+            # sleep a bit to not produce 100% CPU load
+            time.sleep(0.1)
+            try:
+                # try to read a message from PIPE
+                message = os.read(self.pipe_read, 500)
+                if message:
+                    # split PIPE content by lines and put them into queue
+                    for line in message.decode().strip().splitlines():
+                        self.message_queue.put(line)
+                    # set new message flag to start processing
+                    self.message_event.set()
+            except Exception as err:
+                # ignore the "Resource temporarily unavailable" error
+                if err.errno != 11:
+                    logger.error("Error receiving message: {}".format(err))
+
+        logger.debug("Closing FIFO pipe")
+        os.close(self.pipe_read)
+
+
+# handle SIGTERM signal to allow finish all messages processing
+def sigterm_handle(signum, frame):
+    logger.info("Ending processing: Received SIGTERM signal")
+    fifo.stopme.set()
+    thread_wait_message.join()
+    fifo.message_event.set()
+    thread_process_message.join()
+
+
+signal.signal(signal.SIGTERM, sigterm_handle)
+
+# init our class
+fifo = KeepalivedFifo()
+# try to create PIPE if it is not exist yet
+# It looks like keepalived do it before the script will be running, but if we
+# will decide to run this not from keepalived config, then we may get in
+# trouble. So it is betteer to leave this here.
+fifo.pipe_create()
+# create and run dedicated threads for reading and processing messages
+thread_wait_message = threading.Thread(target=fifo.pipe_wait)
+thread_process_message = threading.Thread(target=fifo.pipe_process)
+thread_wait_message.start()
+thread_process_message.start()