Alert in monit

Every monitor tool should have a good alert functional to tell administrator about issues and monit is not an exception. Traditionally, monit allows us to contact with manager by sending email to report about any error happened to monitored services.

1. Enable email alert in monit

By default, if you don't define a notify statement, monit will not send alert messsages. There are two forms of alert statement:
-Global: enable alert to all services.
-Local: enable alert for individual service.
 Recipients in global and local lists are notified when service failed, recovered or changed. If you define both global and local recipients, the local recipient will override.
To set a global alert message, in global section using the "set" keyword

set alert recipient@domain.foo

When this statement is defined, all services being monitored will send messages to address recipient@domain.foo when something goes wrong.

To locally set alert function for each service

 check file test_alert with path "/home/cuong/testfile"
        alert abc@localhost
        if failed permission 0777 then alert

2.  Configurations for email notifications

2.1. Define mail server

Mail server is defined in global section using "set" keyword:

 SET MAILSERVER [hostname/ip] [port]

2.2. Alert message layout

monit provides a default layout for notification message, you can define of your own style. An example of standard layout

set mail-format {
        from:  monit@$HOST
        subject: monit alert -- $EVENT $SERVICE
        message: $EVENT Service $SERVICE
                Date: $DATE
                Action: $ACTION
                Host: $HOST
                Description: $DESCRIPTION
        monit by cuongnv at $DATE
}

Result:

From: monit@Deb6
To: cuong@localhost
Subject: monit alert -- Connection failed exim4
Date: Sat, 20 Apr 2013 14:25:12 GMT
X-Mailer: monit 5.5
MIME-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 8bit

Connection failed Service exim4
                Date: Sat, 20 Apr 2013 21:25:12
                Action: restart
                Host: Deb6
                Description: failed protocol test [SMTP] at INET[localhost:25] via TCP -- SMTP: error receiving data -- Resource temporarily unavailable

        monit by cuongnv at Sat, 20 Apr 2013 21:25:12