nstwatchdog

Name

nstwatchdog — A watchdog script implementation to reboot the NST system upon a test event failure (e.g., ping).

Synopsis

Description

The nstwatchdog script is used to reboot an NST system when a configured number of test events have failed. Currently, only a network ping test event has been implemented.

This script typically runs as a systemd service: "/usr/lib/systemd/system/nstwatchdog.service". One configures options for this service in file: "/etc/sysconfig/nstwatchdog".

Logs / Statistics

Since the nstwatchdog runs as a service, one can use the command: "journalctl -f --unit nstwatchdog.service" to monitor its operational behavior.

A statistcs file: "/var/nst/nstwatchdog/nstwatchdog.log" is also used to log various statistics on the operational behavior of nstwatchdog including start, stop, reboot information and failed test event counts. Sending a SIGUSR1 signal to the running systemd nstwatchdog service unit: "systemctl kill -s SIGUSR1 nstwatchdog.service" will also dump its current counters to the statistics file.

Options

The following command line options are available:

[-m TEXT] | [--mode TEXT]: This option specifies an operational nstwatchdog mode. Currently the following modes: 'ping' and 'stats' are supported. The 'ping' mode specifies a network ping test event configuration. If the "--target-host" can not be reached in "--failed-max-events" trys, then the NST system will be rebooted using the systemd command: '/usr/bin/systemctl reboot;'. The 'stats' mode will dump statistics of a running systemd instance of nstwatchdog to file: "/var/nst/nstwatchdog/nstwatchdog.log".
[-i DEVICE] | [--interface DEVICE]: Use this option to select a network interface to use with the ping command. This is an optional argument to be used with mode: "--mode ping".
[-t HOSTNAME|IPv4ADDR|IPv6ADDR] | [--target-host HOSTNAME|IPv4ADDR|IPv6ADDR]: Use this option to select the target host to ping with mode: "--mode ping". The target host can be either a "IPv4 / IPv6 Address" or a "Host Name". This option is required with mode: "--mode ping".
[-s NUMBER] | [--sleep-interval NUMBER]: This option is used to set the sleep interval between each test event. The value can be specified as a real number of seconds (e.g., 1.5 seconds). Default: 1.0 seconds.
[-f INTEGER] | [--max-failed-events INTEGER]: This option is used to set the maximum number of sequential failed test events to occur before the system is rebooted. Default: 30 sequential failures.
[-q [true]|false] | [--quiet [true]|false]: This option is used to bypass the actual rebooting of the system. It's intended use is for testing purposes only.
[-h [true]|false] | [--help [true]|false]: When this option is specified, nstwatchdog will display a short one line description of nstwatchdog, followed by a short description of each of the supported command line options. After displaying this information nstwatchdog will terminate.
[-H [true]|false] | [--help-long [true]|false]: This option will attempt to pull up additional nstwatchdog documentation within a text based web browser. You can force which browser we use setting the environment variable TEXTBROWSER, otherwise, we will search for some common ones.
[-v [true]|false] | [--verbose [true]|false]: When you set this option to true, nstwatchdog will produce additional output. This is typically used for diagnostic purposes to help track down when things go wrong.
[--version [true]|false]: If this option is specified, the version number of the script is displayed.

Files

/etc/sysconfig/nstwatchdog: The environment file containing command line options for the nstwatchdog script used by the systemd unit service file running this script.
/usr/lib/systemd/system/nstwatchdog.service: The systemd unit service file running this script.
/var/nst/nstwatchdog/nstwatchdog.log: A statistics log file generated by the nstwatchdog script.

Environment

TEXTBROWSER: This controls what text based browser is used to display help information about the script. If not set, we will search your system for available text-based browsers (Ex: elinks, lynx ...).