Takashi Kajinami 0416ccec8c Introduce Guru Meditation Reports into Aodh

This change introduces support for Guru Meditation Report(GMR) into
Aodh, using oslo.reportis library.
With this change, each service prints GMR to stderr or file when
the service receives SIGUSR1.

The same was introduced into Cilometer a long ago[1], and this change
is based on the change made in Ceilometer.
 [1] https://review.opendev.org/c/openstack/ceilometer/+/196369

Change-Id: I7f67acd98c2089bb248d3249159719a3979d27e7

2021-08-15 03:23:23 +09:00

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Guru Meditation Reports

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

Generating a GMR

A GMR can be generated by sending the USR1 signal to any Aodh process with support (see below). The GMR will then be outputted standard error for that particular process.

For example, suppose that aodh-listener has process id 8675, and was run with 2>/var/log/aodh/aodh-listener.log. Then, kill -USR1 8675 will trigger the Guru Meditation report to be printed to /var/log/aodh/aodh-listener.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
Threads: Shows stack traces and thread ids for each of the threads within this process
Green Threads: 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 (currently residing in oslo-incubator), as well as the Aodh version module:

from oslo_reports import guru_meditation_report as gmr
from aodh 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 (usually service.server(server) or something similar), 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 about oslo.reports: oslo.reports

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