Monitor linux web-servers with monit

"monit is a utility for managing and monitoring processes, files, directories and devices on a Unix system. Monit conducts automatic maintenance and repair and can execute meaningful causal actions in error situations. E.g. monit can start a process if it does not run, restart a process if it does not respond and stop a process if it uses to much resources. You may use monit to monitor files, directories and devices for changes, such as timestamps changes, checksum changes or size changes.

Monit is controlled via an easy to configure control file based on a free-format, token-oriented syntax. Monit logs to syslog or to its own log file and notifies you about error conditions via customizable alert messages. Monit can perform various TCP/IP network checks, protocol checks and can utilize SSL for such checks. Monit provides a http(s) interface and you may use a browser to access the monit program."[ref] .

How to install in ubuntu 8.10

• sudo apt-get install monit
• edit /etc/monit/monitrc and remove comments
  #launch system mon every 2min
  set daemon 120
  #set web interface on port 2812
  set httpd port 2812 and
  # allow localhost and request from IP 1.2.3.4
  allow localhost
  allow 1.2.3.4
  #request username (admin) and password(monit)
  allow admin:monit
  #check apache
  check process apache with pidfile /usr/local/apache/logs/httpd.pid
  #check mysql service (other server)
  check host myserver with address 192.168.1.1
  if failed icmp type echo count 3 with timeout 3 seconds then alert
  if failed port 3306 protocol mysql with timeout 15 seconds then alert
  #set alerts via email
  set mailserver mail.domain.com
  set alert administrator@domain.com
• check the syntax of the previous file with
  sudo monit -t
• edit /etc/default/monit
  startup=1
• start deamon !!
  sudo /etc/init.d/monit start
• call web interface
  http://yourserverip:2812/
  use admin and password specified before