Massimiliano Ziccardi - JNRPE

next

Overview

JNRPE provides a Java and a Javascript (Node.js) implementation of the NRPE server. The main features of JNRPE are:

  • Execute existing plugins: by using JNRPE you won't lose the huge amount of already existing Nagios plugins
  • Write plugins with JAVA or Javascript: while current plugins must be compiled for every platform you need to run them on, JNRPE plugins can be used everywhere without any need to recompile
  • Execute the Java plugins directly inside JNRPE: no new JVMs will be instantiated to execute java plugins.

How it works

JNRPE Overview

  1. Nagios will invoke a check defined as a check_nrpe command.
  2. check_nrpe will invoke the command on the JNRPE server
  3. The Socket Listener (that implements the NRPE protocol) will parse and validate the received packet. If the packet is valid, it will ask the executor to execute the received command.
  4. The executor will ask the Command Registry to retrieve the command definition for the requested command
  5. After receiving the command, the executor will ask the command definition to create a COMMAND INSTANCE passing to the command definition all the received parameters. A COMMAND INSTANCE will contain teh requested plugin and all the parameters (replacing the $ARGx$ macros if needed).
  6. When a COMMAND INSTANCE is received, the executor will execute the command instance and return the result to the Socket Listener.
  7. The Socket Listener will then create a NRPE packet with the received result and will return that to check_nrpe.
  8. check_nrpe returns the check result to Nagios

Involved components

  • Nagios: this is your Nagios server
  • check_nrpe: this is a nagios plugin that implements the NRPE protocol
  • JNRPE: the Java implementation of NRPE. This is composed by a number of submodules:
    • SERVER. This module is responsible of receive requests and return responses
    • Config provider. This module is responsible of returning the JNRPE configuration. Currently only file based yaml provider is supported, but other modules to read the configuration from other sources/format can be easily added.
    • Network Listener. This module listen on the network for NRPE requests and routes received requests to the JNRPE SERVER module. More than one Network Listener module can run at the same time. For example, we could have both NRPE Socket and REST listeners active at the same time. In the current version, only NRPE Socket is implemented.
    • EXECUTOR. This module is invoked to execute the request received. It relies on the Command Registry to retrieve all the details needed to satisfy the request (plugins, parameters, etc.)