Add Devstack Installation Guide

This commit added a guide to test out oslo.metrics using Devstack.

Change-Id: I2e9c8eb5da687684df3dcd897ce1f90a18a11dbf

doc/source/user/usage.rst

@@ -6,3 +6,88 @@ A simple example of oslo.metrics in use::
 
     $ oslo-metrics
     2020-06-11 15:59:53.459 5435 INFO oslo.metrics.__main__ [-] Start oslo.metrics
+
+Testing with DevStack
+#####################
+
+This section describes how to test out oslo.metrics and collect oslo.messaging metric data using Devstack.
+
+Download DevStack
+-----------------
+
+.. code-block:: console
+
+   $ git clone https://opendev.org/openstack/devstack
+   $ cd devstack
+
+The ``devstack`` repo contains a script that installs OpenStack and
+templates for configuration files.
+
+Create a local.conf
+-------------------
+
+Create a ``local.conf`` file with four passwords preset at the root of the
+devstack git repo.
+
+.. code-block:: ini
+
+   [[local|localrc]]
+   ADMIN_PASSWORD=secret
+   DATABASE_PASSWORD=$ADMIN_PASSWORD
+   RABBIT_PASSWORD=$ADMIN_PASSWORD
+   SERVICE_PASSWORD=$ADMIN_PASSWORD
+   LIBS_FROM_GIT=oslo.messaging
+
+   [[post-config|$NOVA_CONF]]
+   [oslo_messaging_metrics]
+   metrics_enabled = True
+
+This is the minimum required config to get started with Devstack including
+oslo.metrics.
+
+Start the install
+-----------------
+
+.. code-block:: console
+
+   $ ./stack.sh
+
+This will take a 15 - 20 minutes, largely depending on the speed of
+your internet connection. Many git trees and packages will be
+installed during this process.
+
+Start the Metrics Server
+------------------------
+
+.. code-block:: console
+
+   $ oslo-metrics
+
+This command will start oslo.metrics server and start collecting
+oslo.messaging metrics sending from OpenStack services.
+
+oslo.metrics exporter will serve on port 3000 by default.
+
+Example Output
+--------------
+
+An example of oslo.metrics collecting metrics from Nova:
+
+.. code-block:: console
+
+   ubuntu@devstack:~/devstack$ oslo-metrics
+   2021-06-12 14:32:26.091 466289 INFO oslo.metrics.__main__ [-] Start oslo.metrics
+   2021-06-12 14:57:50.632 466289 DEBUG oslo.metrics.__main__ [-] wait for socket.recv serve /usr/local/lib/python3.8/dist-packages/oslo_metrics/__main__.py:73
+   2021-06-12 14:57:50.632 466289 DEBUG oslo.metrics.__main__ [-] got message serve /usr/local/lib/python3.8/dist-packages/oslo_metrics/__main__.py:76
+   2021-06-12 14:57:50.633 466289 INFO oslo.metrics.message_router [-] Get labels with rpc_client_processing_seconds: {'call_type': 'call', 'exchange': None, 'topic': 'conductor', 'namespace': 'baseapi', 'version': '1.0', 'server': None, 'fanout': None, 'method': 'ping', 'timeout': None, 'process': ''}
+   2021-06-12 14:57:50.633 466289 INFO oslo.metrics.message_router [-] Perform action observe for rpc_client_processing_seconds metrics
+   2021-06-12 14:57:50.633 466289 DEBUG oslo.metrics.__main__ [-] wait for socket.recv serve /usr/local/lib/python3.8/dist-packages/oslo_metrics/__main__.py:73
+   2021-06-12 14:57:50.633 466289 DEBUG oslo.metrics.__main__ [-] got message serve /usr/local/lib/python3.8/dist-packages/oslo_metrics/__main__.py:76
+   2021-06-12 14:57:50.633 466289 INFO oslo.metrics.message_router [-] Get labels with rpc_client_invocation_end_total: {'call_type': 'call', 'exchange': None, 'topic': 'conductor', 'namespace': 'baseapi', 'version': '1.0', 'server': None, 'fanout': None, 'method': 'ping', 'timeout': None, 'process': ''}
+   2021-06-12 14:57:50.633 466289 INFO oslo.metrics.message_router [-] Perform action inc for rpc_client_invocation_end_total metrics`
+
+Gathering Metrics
+-----------------
+
+To gather metrics from oslo.metrics, configure Prometheus to scrape from port
+3000 where oslo.metrics is running.