Email (SMTP) event handler

The Email event handler sends alert messages via SMTP/email.

Configuration

Configuration as well as default option values for the Email event handler are set in the [smtp] section of your kapacitor.conf. Below is an example configuration:

[smtp]
  enabled = true
  host = "localhost"
  port = 25
  username = "username"
  password = "passw0rd"
  from = "me@example.com"
  to = ["me@example.com", "you@example.com"]
  no-verify = false
  idle-timeout = "30s"
  global = false
  state-changes-only = false

enabled

Set to true to enable the SMTP event handler.

host

The SMTP host.

port

The SMTP port.

username

Your SMTP username.

password

Your SMTP password.

from

The “From” address for outgoing mail.

to

List of default “To” addresses.

no-verify

Skip TLS certificate verification when connecting to the SMTP server.

idle-timeout

The time after which idle connections are closed.

global

If true, all alerts will be sent via Email without explicitly specifying the SMTP handler in the TICKscript.

state-changes-only

Sets all alerts in state-changes-only mode, meaning alerts will only be sent if the alert state changes. Only applies if global is true.

Options

The following Email event handler options can be set in a handler file or when using .email() in a TICKscript.

Example: handler file

id: handler-id
topic: topic-name
kind: smtp
options:
  to:
    - oncall1@example.com
    - oncall2@example.com

Example: TICKscript

|alert()
  // ...
  .email()
    .to('oncall1@example.com')
    .to('oncall2@example.com')

  // OR
  .email('oncall1@example.com')
    .to('oncall2@example.com')

Using the SMTP/Email event handler

The Email event handler can be used in both TICKscripts and handler files to email alerts. The email subject is the AlertNode.Message property. The email body is the AlertNode.Details property. The emails are sent as HTML emails so the body can contain html markup.

SMTP settings in kapacitor.conf

[smtp]
  enabled = true
  host = "smtp.myserver.com"
  port = 25
  username = "username"
  password = "passw0rd"
  from = "me@emyserver.com"
  to = ["oncall0@mydomain.com"]
  no-verify = false
  idle-timeout = "30s"
  global = false
  state-changes-only = false

Email alerts from a TICKscript

The following TICKscript uses the .email() event handler to send out emails whenever idle CPU usage drops below 10%.

email-cpu-alert.tick

stream
  |from()
    .measurement('cpu')
  |alert()
    .crit(lambda: "usage_idle" < 10)
    .message('Hey, check your CPU')
    .email()
      .to('oncall1@mydomain.com')
      .to('oncall2@mydomain.com')

Email alerts from a defined handler

The following setup sends an alert to the cpu topic with the message, “Hey, check your CPU”. An email handler is added that subscribes to the cpu topic and emails all alerts.

Create a TICKscript that publishes alert messages to a topic. The TICKscript below sends an alert message to the cpu topic any time idle CPU usage drops below 10%.

cpu_alert.tick

stream
  |from()
    .measurement('cpu')
  |alert()
    .crit(lambda: "usage_idle" < 10)
    .message('Hey, check your CPU')
    .topic('cpu')

Add and enable the TICKscript:

kapacitor define cpu_alert -tick cpu_alert.tick
kapacitor enable cpu_alert

Create a handler file that subscribes to the cpu topic and uses the email or smtp event handler to email alerts.

email_cpu_handler.yaml

id: email-cpu-alert
topic: cpu
kind: smtp
options:
  to:
    - oncall1@mydomain.com
    - oncall2@mydomain.com

Add the handler:

kapacitor define-topic-handler email_cpu_handler.yaml

Send email alerts using the toTemplate option

You can use toTemplate to derive email addresses directly from data instead of hardcoding them individually. In the example below, we are using both the to option and toTemplates option in order to derive email addresses from a dataset and send email alerts directly to recipients. Like the to option, the toTemplates option can be used more than once in a TICKscript. You can combine the to and toTemplates options or use them individually depending on your use case.

stream
	|from()
		.measurement('cpu')
		.where(lambda: "host" == 'serverA')
		.groupBy('host')
	|window()
		.period(10s)
		.every(10s)
	|count('value')
	|default()
		.field('extraemail','bob@example.com')
		.tag('tagemail','bob2@example.com')
	|alert()
		.id('kapacitor.{{ .Name }}.{{ index .Tags "host" }}')
		.details('''
<b>{{.Message}}</b>
Value: {{ index .Fields "count" }}
<a href="http://graphs.example.com/host/{{index .Tags "host"}}">Details</a>
''')
		.info(lambda: "count" > 6.0)
		.warn(lambda: "count" > 7.0)
		.crit(lambda: "count" > 8.0)
		.email()
			.to('user1@example.com', 'user2@example.com')
			.toTemplates('{{ index .Fields "extraemail" }}')