Smokeping is a very useful daemon which can run a number of checks at certain intervals. Out of the box it will perform ping tests on hosts every 5 minutes. It can however be setup to monitor websites and response/connection times.

Updated for Debian Bullseye

 apt-get install smokeping

By default apache2 config gets enabled:
/etc/apache2/conf-enabled/smokeping.conf
So http://domain/smokeping  will be work straight away. May want to change.

 vi /etc/smokeping/config.d/General
 #update contact and name etc.

vi /etc/smokeping/config.d/Targets
 + Burkesys_Cluster
 menu = Burkesys Cluster
 title = Burkesys Cluster
 
 ++ burkesys
 menu = Burkesys
 title = burkesys.burkesys.com
 host = burkesys.burkesys.com
 
 ++ twister
 menu = Twister
 title = twister.burkesys.com
 host = twister.burkesys.com

With some trial and error you'll get it. Apache should be setup with the following config: /etc/apache2/conf.d/smokeping. Just go to http://server/smokeping/smokeping.cgi Also watch /var/log/daemon.log where the smokeping daemon will send logs.

 vi /etc/smokeping/config.d/Probes
 #Under *** Probes ***, you will see FPing. Add this under it.
 
 + Curl
 
 binary = /usr/bin/curl
 extraargs = --head
 pings = 5
 urlformat = http://%host%/

 vi /etc/smokeping/config.d/Targets
 
 ++ www_burkesys
 probe = Curl
 menu = Burkesys(www)
 title = burkesys.burkesys.com(www)
 host = www.burkesys.com

 apt-get install curl
 #check that /usr/bin/curl exists.
 /etc/init.d/smokeping restart

 vi /etc/smokeping/config.d/Probes
 + DNS
 
 binary = /usr/bin/dig
 pings = 5
 step = 300
 timeout = 15

 vi /etc/smokeping/config.d/Targets
 ++ ns1_burkesys_com
 probe = DNS
 menu = Burkesys (ns1)
 title = Burkesys NS Server(ns1.burkesys.com)
 host = ns1.burkesys.com
 lookup = burkesys.com
 server = ns1.burkesys.com

/etc/init.d/smokeping restart

 /etc/init.d/smokeping stop
 smokeping --debug