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-rwxr-xr-xsrc/system/vyos-event-handler.py162
1 files changed, 162 insertions, 0 deletions
diff --git a/src/system/vyos-event-handler.py b/src/system/vyos-event-handler.py
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+++ b/src/system/vyos-event-handler.py
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+#!/usr/bin/env python3
+#
+# Copyright (C) 2022 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 argparse
+import json
+import re
+import select
+from copy import deepcopy
+from os import getpid, environ
+from pathlib import Path
+from signal import signal, SIGTERM, SIGINT
+from sys import exit
+from systemd import journal
+
+from vyos.util import run, dict_search
+
+# Identify this script
+my_pid = getpid()
+my_name = Path(__file__).stem
+
+
+# handle termination signal
+def handle_signal(signal_type, frame):
+ if signal_type == SIGTERM:
+ journal.send('Received SIGTERM signal, stopping normally',
+ SYSLOG_IDENTIFIER=my_name)
+ if signal_type == SIGINT:
+ journal.send('Received SIGINT signal, stopping normally',
+ SYSLOG_IDENTIFIER=my_name)
+ exit(0)
+
+
+# Class for analyzing and process messages
+class Analyzer:
+ # Initialize settings
+ def __init__(self, config: dict) -> None:
+ self.config = {}
+ # Prepare compiled regex objects
+ for event_id, event_config in config.items():
+ script = dict_search('script.path', event_config)
+ # Check for arguments
+ if dict_search('script.arguments', event_config):
+ script_arguments = dict_search('script.arguments', event_config)
+ script = f'{script} {script_arguments}'
+ # Prepare environment
+ environment = deepcopy(environ)
+ # Check for additional environment options
+ if dict_search('script.environment', event_config):
+ for env_variable, env_value in dict_search(
+ 'script.environment', event_config).items():
+ environment[env_variable] = env_value.get('value')
+ # Create final config dictionary
+ pattern_raw = event_config['filter']['pattern']
+ pattern_compiled = re.compile(
+ rf'{event_config["filter"]["pattern"]}')
+ pattern_config = {
+ pattern_compiled: {
+ 'pattern_raw':
+ pattern_raw,
+ 'syslog_id':
+ dict_search('filter.syslog-identifier', event_config),
+ 'pattern_script': {
+ 'path': script,
+ 'environment': environment
+ }
+ }
+ }
+ self.config.update(pattern_config)
+
+ # Execute script safely
+ def script_run(self, pattern: str, script_path: str,
+ script_env: dict) -> None:
+ try:
+ run(script_path, env=script_env)
+ journal.send(
+ f'Pattern found: "{pattern}", script executed: "{script_path}"',
+ SYSLOG_IDENTIFIER=my_name)
+ except Exception as err:
+ journal.send(
+ f'Pattern found: "{pattern}", failed to execute script "{script_path}": {err}',
+ SYSLOG_IDENTIFIER=my_name)
+
+ # Analyze a message
+ def process_message(self, message: dict) -> None:
+ for pattern_compiled, pattern_config in self.config.items():
+ # Check if syslog id is presented in config and matches
+ syslog_id = pattern_config.get('syslog_id')
+ if syslog_id and message['SYSLOG_IDENTIFIER'] != syslog_id:
+ continue
+ if pattern_compiled.fullmatch(message['MESSAGE']):
+ # Add message to environment variables
+ pattern_config['pattern_script']['environment'][
+ 'message'] = message['MESSAGE']
+ # Run script
+ self.script_run(
+ pattern=pattern_config['pattern_raw'],
+ script_path=pattern_config['pattern_script']['path'],
+ script_env=pattern_config['pattern_script']['environment'])
+
+
+if __name__ == '__main__':
+ # Parse command arguments and get config
+ parser = argparse.ArgumentParser()
+ parser.add_argument('-c',
+ '--config',
+ action='store',
+ help='Path to even-handler configuration',
+ required=True,
+ type=Path)
+
+ args = parser.parse_args()
+ try:
+ config_path = Path(args.config)
+ config = json.loads(config_path.read_text())
+ # Create an object for analazyng messages
+ analyzer = Analyzer(config)
+ except Exception as err:
+ print(
+ f'Configuration file "{config_path}" does not exist or malformed: {err}'
+ )
+ exit(1)
+
+ # Prepare for proper exitting
+ signal(SIGTERM, handle_signal)
+ signal(SIGINT, handle_signal)
+
+ # Set up journal connection
+ data = journal.Reader()
+ data.seek_tail()
+ data.get_previous()
+ p = select.poll()
+ p.register(data, data.get_events())
+
+ journal.send(f'Started with configuration: {config}',
+ SYSLOG_IDENTIFIER=my_name)
+
+ while p.poll():
+ if data.process() != journal.APPEND:
+ continue
+ for entry in data:
+ message = entry['MESSAGE']
+ pid = entry['_PID']
+ # Skip empty messages and messages from this process
+ if message and pid != my_pid:
+ try:
+ analyzer.process_message(entry)
+ except Exception as err:
+ journal.send(f'Unable to process message: {err}',
+ SYSLOG_IDENTIFIER=my_name)