Event handler allows you to execute scripts when a string that matches a regex or a regex with a service name appears in journald logs. You can pass variables, arguments, and a full matching string to the script.
.. cfgcmd:: set service event-handler event <event-handler name>This is an optional command because the event handler will be automatically created after any of the next commands.
.. cfgcmd:: set service event-handler event <event-handler name> filter pattern <regex>This is a mandatory command. Sets regular expression to match against log string message.
Note
The regular expression matches if and only if the entire string matches the pattern.
.. cfgcmd:: set service event-handler event <event-handler name> script path <path to script>This is a mandatory command. Sets the full path to the script. The script file must be executable.
.. cfgcmd:: set service event-handler event <event-handler name> filter syslog-identifier <sylogid name>This is an optional command. Filters log messages by syslog-identifier.
.. cfgcmd:: set service event-handler event <event-handler name> script environment <env name> value <env value>This is an optional command. Adds environment and its value to the script. Use separate commands for each environment.
One implicit environment exists.
message
: Full message that has triggered the script... cfgcmd:: set service event-handler event <event-handler name> script arguments <arguments>This is an optional command. Adds arguments to the script. Arguments must be separated by spaces.
Note
We don't recomend to use arguments. Using environments is more preffereble.
Event handler that monitors the state of interface eth0.
set service event-handler event INTERFACE_STATE_DOWN filter pattern '.*eth0.*,RUNNING,.*->.*' set service event-handler event INTERFACE_STATE_DOWN filter syslog-identifier 'netplugd' set service event-handler event INTERFACE_STATE_DOWN script environment interface_action value 'down' set service event-handler event INTERFACE_STATE_DOWN script environment interface_name value 'eth2' set service event-handler event INTERFACE_STATE_DOWN script path '/config/scripts/eventhandler.py'Event handler script
#!/usr/bin/env python3 # # VyOS event-handler script example from os import environ import subprocess from sys import exit # Perform actions according to requirements def process_event() -> None: # Get variables message_text = environ.get('message') interface_name = environ.get('interface_name') interface_action = environ.get('interface_action') # Print the message that triggered this script print(f'Logged message: {message_text}') # Prepare a command to run command = f'sudo ip link set {interface_name} {interface_action}'.split() # Execute a command subprocess.run(command) if __name__ == '__main__': try: # Run script actions and exit process_event() exit(0) except Exception as err: # Exit properly in case if something in the script goes wrong print(f'Error running script: {err}') exit(1)