Sensu Plugin - Mailer

This handler formats alerts as e-mails and sends them off to a pre-defined recipient. [1]

Basic information

  • License: MIT License

Installation

Note

The entire process of installation and configuration has to be executed only in the Sensu Server.

The handler is a Ruby script that can be downloaded from the official repository: https://github.com/sensu-plugins/sensu-plugins-mailer/blob/master/bin/handler-mailer.rb.

It can be located in /etc/sensu/handlers/mailer.rb

Configuration

Add the Mailer configuration file and set correctly which will be the SMTP server, the sender, the mail recipients, etc:

Example: /etc/sensu/conf.d/handlers/mailer.json

{
  "mailer": {
    "mail_from": "sensu@example.com",
    "mail_to": [
      "mail1@example.com",
      "mail2@example.com"
    ],
    "smtp_address": "smtp.server.host.example.com",
    "smtp_port": "25",
    "smtp_domain": "example.com"
  },
  "handlers": {
    "mailer": {
      "type": "pipe",
      "filter": "state-change-only",
      "command": "/opt/sensu/embedded/bin/handler-mailer.rb"
    }
  }
}

In this example, the handler definition has the filter state-change-only associated. This filter executes the mailer handler to send mail only when there is a change in the state, that means, in the first occurrence of the state. When a check is in state OK, it doesn’t count occurrences, that’s why it’s necessary to have both conditions in the conditional.

That filter is defined as follows:

Example: /etc/sensu/conf.d/filters.json

{
  "filters": {
    "state-change-only": {
      "negate": false,
      "attributes": {
        "occurrences": "eval: value == 1 || ':::action:::' == 'resolve'"
      }
    }
  }
}

Usage

Follow these steps to add mailer as a handler that will send a mail when there is a state change in a specific monitoring check:

  1. Add Mailer as a handler in the check definition:

    {
  "checks": {
    "check_example": {
      "command": "check-example.rb",
      "subscribers": ["examples"],
      "interval": 60,
      "handlers": ["mailer"]
    }
  }
}

  2. Restart sensu-server and sensu-api services.

References