event-handler: T3083: Add simple event-handler

Event-handler allows executing a custom script when in logs it
detects configured "pattern"
A simple implemenation

set system event-handler first pattern '.*ssh2.*'
set system event-handler first script '/config/scripts/hello.sh'

1 files changed, 55 insertions, 0 deletions

diff --git a/src/helpers/vyos-event-handler.py b/src/helpers/vyos-event-handler.py
new file mode 100755
index 000000000..018a752f4
--- /dev/null
+++ b/src/helpers/vyos-event-handler.py
@@ -0,0 +1,55 @@
+#!/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 select
+import re
+import json
+
+from sys import argv
+from os import getpid
+from systemd import journal
+from vyos.util import call
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument("-c", "--config", action="store", help="Path to even-handler configuration", required=True)
+
+args = parser.parse_args()
+config = args.config
+data = journal.Reader()
+data.seek_tail()
+data.get_previous()
+p = select.poll()
+p.register(data, data.get_events())
+my_pid = getpid()
+
+with open(config, 'r') as f:
+    config = json.load(f)
+
+
+if __name__ == '__main__':
+    while p.poll():
+        if data.process() != journal.APPEND:
+            continue
+        for entry in data:
+            message = entry['MESSAGE']
+            for name, event_config in config.items():
+                pattern = re.compile(rf'{event_config["pattern"]}')
+                script = event_config['script']
+                if message != "" and entry['_PID'] != my_pid and pattern.match(message):
+                    call(script)
+                    journal.send(f'Pattern found: {event_config["pattern"]}, script executed: {script}')