simple bash scripts that monitor a few systemd services.
file: scripts/monitor_apache.sh
Checks if the apache2 service is running, if not and if has crashed, attempts to restart it after period of time which can be defined with the DOWNTIME_BEFORE_RESTART environment variable (default: 900 secs).
You can also configure a slack notification by defining the variable APACHE_MONITOR_SLACK_HOOK.
If defined, the script will send a notification message with details in case of errors.
When configuring this script with a cron job, don't forget to use flock to avoid double executions.
Example:
*/5 * * * * flock -n /tmp/apache_monitor.lock -c "/path/to/scripts_dir/apache_monitor.sh"
flock will ensure single execution if the script takes too long.