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14 Plugins

Overview

Plugins provide an option to extend the monitoring capabilities of �����IJ�. Plugins are written in Go programming language and are supported by �����IJ� agent 2 only.

Plugins provide an alternative to loadable modules (written in C), and other methods for extending �����IJ� functionality, such as user parameters (agent metrics), external checks (agent-less monitoring), and system.run[] �����IJ� agent item.

The following features are specific to �����IJ� agent 2 and its plugins:

• support of scheduled and flexible intervals for both passive and active checks;
• task queue management with respect to schedule and task concurrency;
• plugin-level timeouts;
• compatibility check of �����IJ� agent 2 and its plugins on start up.

Since �����IJ� 6.0.0, plugins don't have to be integrated into the agent 2 directly and can be added as loadable plugins, thus making the creation process of additional plugins for gathering new monitoring metrics easier.

This page lists �����IJ� native and loadable plugins, and describes plugin configuration principles from the user perspective. For instructions about writing your own plugins, see Plugin development guidelines. For more information on the communication process between �����IJ� agent 2 and a loadable plugin, as well as the metrics collection process, see Connection diagram.

Configuring plugins

This section provides common plugin configuration principles and best practices.

All plugins are configured using Plugins.* parameter, which can either be part of the �����IJ� agent 2 configuration file or a plugin's own configuration file. If a plugin uses a separate configuration file, path to this file should be specified in the Include parameter of �����IJ� agent 2 configuration file.

Each plugin parameter should have the following structure:

Plugins.<PluginName>.<Parameter>=<Value>

Parameter names should adhere to the following requirements:

• it is recommended to capitalize the names of your plugins;
• the parameter should be capitalized;
• special characters are not allowed;
• nesting isn’t limited by a maximum level;
• the number of parameters is not limited.

Named sessions

Named sessions represent an additional level of plugin parameters and can be used to define separate sets of authentication parameters for each of the instances being monitored. Each named session parameter should have the following structure:

Plugins.<PluginName>.Sessions.<SessionName>.<Parameter>=<Value>

A session name can be used as a connString item key parameter instead of specifying a URI, username, and password separately. In item keys, the first parameter can be either a connString or a Uri. If the first key parameter matches a session name specified in the configuration file, the check will be executed using named session parameters. If the first key parameter doesn't match any session name, it will be treated as a Uri.

Note, that:

• when providing a connString (session name) in key parameters, key parameters for username and password must be empty;
• passing embedded URI credentials is not supported, consider using named sessions instead;
• in case an authentication parameter is not specified for the named session, a hardcoded default value will be used.

The list of available named session parameters depends on the plugin, see individual plugin configuration files for details.

Example: Monitoring of two instances “MySQL1” and “MySQL2” can be configured in the following way:

Plugins.Mysql.Sessions.MySQL1.Uri=tcp://127.0.0.1:3306
       Plugins.Mysql.Sessions.MySQL1.User=<UsernameForMySQL1>
       Plugins.Mysql.Sessions.MySQL1.Password=<PasswordForMySQL1>    
       Plugins.Mysql.Sessions.MySQL2.Uri=tcp://127.0.0.1:3307   
       Plugins.Mysql.Sessions.MySQL2.User=<UsernameForMySQL2>
       Plugins.Mysql.Sessions.MySQL2.Password=<PasswordForMySQL2>

Now, these names may be used as connStrings in keys instead of URIs:

mysql.ping[MySQL1]
       mysql.ping[MySQL2]

Hardcoded defaults

If a parameter required for authentication is not provided in an item key or in the named session parameters, the plugin will use a hardcoded default value.

Connections

Some plugins support gathering metrics from multiple instances simultaneously. Both local and remote instances can be monitored. TCP and Unix-socket connections are supported.

It is recommended to configure plugins to keep connections to instances in an open state. The benefits are reduced network congestion, latency, and CPU and memory usage due to the lower number of connections. The client library takes care of this.

Plugins

All metrics supported by �����IJ� agent 2 are collected by plugins.

Built-in

The following plugins for �����IJ� agent 2 are available out-of-the-box. Click on the plugin name to go to the plugin repository with additional information.

Loadable

Click on the plugin name to go to the plugin repository with additional information.

See also: Building loadable plugins.

Footnotes

¹ - Since �����IJ� 6.2.7, loadable plugins started using the same versioning system as �����IJ� itself. As a result, MongoDB plugin version has changed from 1.2.1 to 6.2.7.