SLA (Service Level Agreement)

Decanter provides a SLA (Service Level Agreement) layer. It allows you to check values of harvested data (coming from the collectors) and send alerts when the data is not in the expected state.

Checker

The SLA checker is automatically installed as soon as you install a SLA alerter feature.

It uses the etc/org.apache.karaf.decanter.sla.checker.cfg configuration file.

This file contains the check to perform on the collected properties.

The format of this file is:

type.propertyName.alertLevel=checkType:value

where:

type is optional. It allows you to filter the SLA check for a given type of collected data. It’s particulary interesting when Decanter collects multiple JMX object names or servers. You may want to perform different checks depending of the type or source of the collected data.
propertyName is the data property key. For instance, loggerName, message, HeapMemoryUsage.used, etc.
alertLevel is the alerting level for this check. The only two possible values are error (critical alert), or warn (severe alert).
checkType is the check type. Possible values are range, equal, notequal, match, and notmatch.
value is the check value, where the data property value has to verify.

The Decanter SLA Checker supports numeric or string check.

To verify a numeric value, you can use:

range to check if the metric is between two values
equal to check if the metric is equal to a value
notequal to check if the metric is not equal to a value

For instance, if you want to check that the number of threads is between 0 and 70, you can use:

ThreadCount.error=range:[0,70]

You can also filter and specify the type on which we check:

jmx-local.ThreadCount.error=range:[0,70]

If the thread count is out of this range, Decanter will create an error alert sent to the alerters.

Another example is if you want to check if the myValue is equal to 10:

myValue.warn=equal:10

If myValue is not equal to 10, Decanter will create a warn alert send to the alerters.

To verify a string value, you can use:

match to check if the metric matches a regex
notmatch to check if the matric doesn’t match a regex

For instance, if you want to create an alert when an ERROR log message happens, you can use:

loggerLevel.error=match:ERROR

You can also use "complex" regex:

loggerName.warn=match:(.*)my\.loggger\.name\.(.*)

Alerters

When the value doesn’t verify the check in the checker configuration, an alert is created an sent to the alerters.

Apache Karaf Decanter provides ready to use alerters.

Log

The Decanter SLA Log alerter log a message for each alert.

The decanter-sla-log feature installs the SLA log alerter:

karaf@root()> feature:install decanter-sla-log

This alerter doesn’t need any configuration.

E-mail

The Decanter SLA e-mail alerter sends an e-mail for each alert.

The decanter-sla-email feature installs the SLA e-mail alerter:

karaf@root()> feature:install decanter-sla-email

This feature also installs the etc/org.apache.karaf.decanter.sla.email.cfg configuration file where you can specify the SMTP server and e-mail addresses to use:

#
# Decanter SLA e-mail alerter configuration
#

# From e-mail address
from=

# To e-mail address
to=

# Hostname of the SMTP server
host=smtp.gmail.com

# Port of the SMTP server
port=587

# enable SMTP auth
auth=true

# enable starttls and ssl
starttls=true
ssl=false

# Optionally, username for the SMTP server
#username=

# Optionally, password for the SMTP server
#password=

the from property specifies the from e-mail address (for instance dev@karaf.apache.org)
the to property specifies the to e-mail address (for instance dev@karaf.apache.org)
the host property specifies the SMTP server hostname or IP address
the port property specifies the SMTP server port number
the auth property (true or false) specifies if the SMTP server requires authentication (true) or not (false)
the starttls property (true or false) specifies if the SMTP server requires STARTTLS (true) or not (false)
the ssl property (true or false) specifies if the SMTP server requires SSL (true) or not (false)
the username property is optional and specifies the username to connect to the SMTP server
the password property is optional and specifies the password to connect to the SMTP server

Camel

The Decanter SLA Camel alerter sends each alert to a Camel endpoint.

It allows you to create a route which reacts to each alert. It’s a very flexible alerter as you can apply transformation, use EIPs, Camel endpoints, etc.

This alerter creates a Camel exchange. The body of the "in" message contains a Map with all alert details (including alertLevel, alertAttribute, alertPattern and all other details).

The decanter-sla-camel feature installs the Camel alerter:

karaf@root()> feature:install decanter-sla-camel

This feature also installs the etc/org.apache.karaf.decanter.sla.camel.cfg configuration file:

#
# Decanter SLA Camel alerter
#

# alert.destination.uri defines the Camel endpoint URI where
# Decanter send the SLA alerts
alert.destination.uri=direct-vm:decanter-alert

This configuration file allows you to specify the Camel endpoint URI where to send the alert (using the alert.destination.uri property).

For instance, in this configuration, if you define:

alert.destination.uri=direct-vm:decanter-alert

You can create the following Camel route which will react to the alert:

<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0">

  <camelContext xmlns="http://camel.apache.org/schema/blueprint">
    <route id="decanter-alert">
      <from uri="direct-vm:decanter-alert"/>
      ...
      ANYTHING
      ...
    </route>
  </camelContext>

</blueprint>