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113 lines
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Copyright (c) 2013 OpenStack Foundation
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All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License"); you may
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not use this file except in compliance with the License. You may obtain
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a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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License for the specific language governing permissions and limitations
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under the License.
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Guru Meditation Reports
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=======================
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Cinder contains a mechanism whereby developers and system administrators can
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generate a report about the state of a running Cinder executable.
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This report is called a *Guru Meditation Report* (*GMR* for short).
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Generating a GMR
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----------------
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A *GMR* can be generated by sending the *USR2* signal to any Cinder process
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with support (see below).
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The *GMR* will then output to standard error for that particular process.
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For example, suppose that ``cinder-api`` has process id ``8675``, and was run
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with ``2>/var/log/cinder/cinder-api-err.log``.
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Then, ``kill -USR2 8675`` will trigger the Guru Meditation report to be printed
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to ``/var/log/cinder/cinder-api-err.log``.
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There is other way to trigger a generation of report, user should add
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a configuration in Cinder's conf file::
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[oslo_reports]
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file_event_handler=['The path to a file to watch for changes to trigger '
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'the reports, instead of signals. Setting this option '
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'disables the signal trigger for the reports.']
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file_event_handler_interval=['How many seconds to wait between polls when '
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'file_event_handler is set, default value '
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'is 1']
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a *GMR* can be generated by "touch"ing the file which was specified in
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file_event_handler. The *GMR* will then output to standard error for
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that particular process.
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For example, suppose that ``cinder-api`` was run with
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``2>/var/log/cinder/cinder-api-err.log``, and the file path is
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``/tmp/guru_report``.
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Then, ``touch /tmp/guru_report`` will trigger the Guru Meditation report to be
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printed to ``/var/log/cinder/cinder-api-err.log``.
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Structure of a GMR
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------------------
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The *GMR* is designed to be extensible; any particular executable may add
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its own sections. However, the base *GMR* consists of several sections:
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Package
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Shows information about the package to which this process belongs,
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including version information
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Threads
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Shows stack traces and thread ids for each of the threads within this process
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Green Threads
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Shows stack traces for each of the green threads within this process
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(green threads don't have thread ids)
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Configuration
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Lists all the configuration options currently accessible via the CONF object
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for the current process
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Adding Support for GMRs to New Executables
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------------------------------------------
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Adding support for a *GMR* to a given executable is fairly easy.
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First import the module (currently residing in oslo-incubator), as well as the
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Cinder version module:
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.. code-block:: python
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from oslo_reports import guru_meditation_report as gmr
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from cinder import version
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Then, register any additional sections (optional):
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.. code-block:: python
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TextGuruMeditation.register_section('Some Special Section',
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some_section_generator)
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Finally (under main), before running the "main loop" of the executable
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(usually ``service.server(server)`` or something similar), register the *GMR*
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hook:
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.. code-block:: python
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TextGuruMeditation.setup_autorun(version)
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Extending the GMR
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-----------------
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As mentioned above, additional sections can be added to the GMR for a
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particular executable. For more information, see the inline documentation
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about oslo.reports:
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`oslo.reports <https://docs.openstack.org/oslo.reports/latest/>`_
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