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

aodh/cmd/aodh-config-generator.conf

@@ -9,4 +9,5 @@ namespace = oslo.middleware.cors
 namespace = oslo.middleware.healthcheck
 namespace = oslo.middleware.http_proxy_to_wsgi
 namespace = oslo.policy
+namespace = oslo.reports
 namespace = keystonemiddleware.auth_token

aodh/service.py

@@ -22,12 +22,14 @@ from oslo_db import options as db_options
 import oslo_i18n
 from oslo_log import log
 from oslo_policy import opts as policy_opts
+from oslo_reports import guru_meditation_report as gmr
 from oslo_utils import importutils
 
 from aodh.conf import defaults
 from aodh import keystone_client
 from aodh import messaging
 from aodh import profiler
+from aodh import version
 
 profiler_opts = importutils.try_import('osprofiler.opts')
 
@@ -96,10 +98,17 @@ def prepare_service(argv=None, config_files=None):
     keystone_client.register_keystoneauth_opts(conf)
 
     conf(argv, project='aodh', validate_default_values=True,
-         default_config_files=config_files)
+         default_config_files=config_files,
+         version=version.version_info.version_string())
 
     ka_loading.load_auth_from_conf_options(conf, "service_credentials")
     log.setup(conf, 'aodh')
+
+    # NOTE(tkajinam): guru cannot run with service under apache daemon, so when
+    # aod-api running with mod_wsgi, the argv is [], we don't start guru.
+    if argv:
+        gmr.TextGuruMeditation.setup_autorun(version)
+
     profiler.setup(conf)
     messaging.setup()
     return conf

aodh/version.py

@@ -0,0 +1,17 @@
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+
+import pbr.version
+
+version_info = pbr.version.VersionInfo('aodh')

doc/source/contributor/gmr.rst

@@ -0,0 +1,89 @@
+..
+      Copyright (c) 2021 OpenStack Foundation
+
+      Licensed under the Apache License, Version 2.0 (the "License"); you may
+      not use this file except in compliance with the License. You may obtain
+      a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+      WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+      License for the specific language governing permissions and limitations
+      under the License.
+
+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:
+
+.. code-block:: python
+
+      from oslo_reports import guru_meditation_report as gmr
+      from aodh import version
+
+Then, register any additional sections (optional):
+
+.. code-block:: python
+
+      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:
+
+.. code-block:: python
+
+      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 <https://docs.openstack.org/oslo.reports/latest/>`_

doc/source/contributor/index.rst

@@ -40,6 +40,7 @@ Developer Documentation
    testing
    contributing
    event-alarm
+   gmr
 
 Appendix
 ========

releasenotes/notes/gmr-3dd0a582af010bd4.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Aodh now supports generation of Guru Meditation Reports using oslo.reports
+    library. Each service prints a report output when it receives SIGUSR1.

requirements.txt

@@ -14,6 +14,7 @@ oslo.config>=6.8.0 # Apache-2.0
 oslo.context>=2.22.0 # Apache-2.0
 oslo.i18n>=1.5.0 # Apache-2.0
 oslo.log>=4.3.0 # Apache-2.0
+oslo.reports>=1.18.0 # Apache-2.0
 oslo.policy>=3.7.0 # Apache-2.0
 oslo.upgradecheck>=1.3.0 # Apache-2.0
 PasteDeploy>=1.5.0