# Guru Meditation Reports¶

Dragonflow contains a mechanism whereby developers and system administrators can generate a report about the state of a running Dragonflow executable. This report is called a Guru Meditation Report (GMR for short).

## Generating a GMR¶

A GMR can be generated by sending the USR2 signal to any Dragonflow process with support (see below). The GMR will then be outputted standard error for that particular process.

For example, suppose that df-local-controller has process id 2525, and was run with 2>/var/log/dragonflow/df-controller.log. Then, kill -USR2 2525 will trigger the Guru Meditation report to be printed to /var/log/dragonflow/df-controller.log.

## Structure of a GMR¶

The GMR is designed to be extensible; any particular executable may add its own sections. However, the base GMR consists of several sections:

Package
Shows information about the package to which this process belongs, including version information
Shows stack traces and thread ids for each of the threads within this process
Shows stack traces for each of the green threads within this process (green threads don’t have thread ids)
Configuration
Lists all the configuration options currently accessible via the CONF object for the current process

## Adding Support for GMRs to New Executables¶

Adding support for a GMR to a given executable is fairly easy.

First import the module, as well as the Dragonflow version module:

from oslo_reports import guru_meditation_report as gmr
from dragonflow import version


Then, register any additional sections (optional):

TextGuruMeditation.register_section('Some Special Section',
some_section_generator)


Finally (under main), before running the “main loop” of the executable, register the GMR hook:

TextGuruMeditation.setup_autorun(version)


## Extending the GMR¶

As mentioned above, additional sections can be added to the GMR for a particular executable. For more information, see the inline documentation under oslo.reports