collmann: riemann event processing inside collectd

collmann is a collectd plugin relying on collectd's java support which embeds a riemann event processor within collectd.

The aim of collmann is to provide a flexible intermediate layer between collectd input plugins and collectd output plugins, by allowing event manipulation.

In addition to the very rich API exposed by riemann, a few collectd specific functions are also available and documented below.

Building

Building collmann is done with the help of leiningen, once installed, just run:

lein uberjar

which will produce an artifact in <collman-dir>/target/collman-0.1.0-standalone.jar

Configuration

Configuration of the plugin happens in a standard riemann configuration file, which you then point to from collectd's configuration.

Riemann configuration

A typical riemann configuration will look like this:

(tcp-server :host "0.0.0.0")

(let [index (update-index (index))]
  (streams
     ;; write out incoming metrics to both the riemann index
	 ;; and back to collectd
	 (where collectd?
	        index
	        collectd-index)))

For additional documentation on the riemann configuration API, please refer to the riemann howto and api documentation.

The corresponding collectd configuration would look like this:

Hostname    "yourname"

LoadPlugin logfile
LoadPlugin cpu
LoadPlugin load
LoadPlugin java

<Plugin logfile>
        File STDOUT
        Timestamp true
        PrintSeverity false
</Plugin>
						
<Plugin java>
        JVMArg     "-Dlog4j.configuration=file:///path/to/collmann/resources/log4j.properties"
        JVMArg     "-Djava.class.path=/path/to/collmann/target/collmann-0.1.0-standalone.jar"
        LoadPlugin "io.exo.collmann.core"
       <Plugin "riemann">
             LoadConfig "/path/to/collmann/doc/collectd.clj"
       </Plugin>
</Plugin>

Api

The following functions are available in addition to the riemann api:

• collectd?: predicate which can be used in where to catch collectd events.
• plugin: predicate builder to catch events from specific plugins
• plugin-instance: predicate builder to catch events from specific plugin-instances
• collectd-type: predicate builder to catch events from specific collectd types
• type-instance: predicate builder to catch events from specific type instances