Author: Josuah

 monitoring suite
==================

 $ while read line; do $line >/dev/null 2>&1 || logger -cs -p local0.alert -t monitor "$line" & done </etc/monitor.conf; wait

 Explanation: It is a monitoring suite, that reads configuration in 
 this form (which can be generated or edited manually):
  
 /etc/monitor.conf
 ~~~
 check-http name=http-suckless host=nuchalis url=https://home.suckless.z0.is/ 
 check-http name=http-suckless host=nuchalis url=https://ev.suckless.org/
 ....

 For each input line, it execute the check-xxx with all arguments, and 
 if it fails, it prints and logs to syslog and standard error (-s flag). 
 If it is ran by cron, you also get an email every time something fails 
 (setup an alias for root to your@mail in /etc/mail/aliases or alike). 
  
 Here is an example of check command: 
  
 ~~~ 
 check-http 
 ~~~ 
 export "$@" 
 : ${method:=GET} # default value 
 exec curl -Ls -X "$method" "$url" >/dev/null

 The mails will look like this: 
 ~~~ 
 From: root@mx1.z0.is (Cron Daemon) 
 To: root@mx1.z0.is 
 Subject: Cron <root@olor> monitor-run 
 Date: Mon, 26 Oct 2020 03:35:03 +0000 (UTC) 
  
 monitower: check-http name=http-suckless host=olor vhost=suckless url=https://home.suckless.z0.is/ 
 monitower: check-mail name=smtp host=olor ip=45.32.148.148 mail=monitor@z0.is 
 monitower: check-mail name=smtp host=olor ip=45.32.148.148 mail=monitor@josuah.net 
 ~~~ 
  
 If there is a VPN between the production machines and admins laptops or 
 if there is a jump host, then syslog can be configured to forward all 
 local0.alert log events to that host, which can then decide to print 
 them out on the terminal and emmit a beep on local machine to get some 
 /dev/speaker beep sound.