Document toggling debug for containerized services

This was not yet covered for containerized services.

Change-Id: I3fe7e9fa811c6671301ba8d02e6771bbbd9c7dd8

doc/source/install/containers_deployment/tips_tricks.rst

@@ -29,6 +29,34 @@ are quite there yet, so we export traditional logs from containers
 into the `/var/log/containers` directory on the host, where you can
 look at them.
 
+.. _toggle_debug:
+
+Toggle debug
+------------
+
+For services that support `reloading their configuration at runtime`_::
+
+    $ sudo docker exec -u root nova_scheduler crudini --set /etc/nova/nova.conf DEFAULT debug true
+    $ sudo docker kill -s SIGHUP nova_scheduler
+
+.. _reloading their configuration at runtime: https://storyboard.openstack.org/#!/story/2001545
+
+Restart the container to turn back the configuration to normal::
+
+    $ sudo docker restart nova_scheduler
+
+Otherwise, if the service does not yet support reloading its configuration, it
+is necessary to change the configuration on the host filesystem and restart the
+container::
+
+    $ sudo crudini --set /var/lib/config-data/puppet-generated/nova/etc/nova/nova.conf DEFAULT debug true
+    $ sudo docker restart nova_scheduler
+
+Apply the inverse change to restore the default log verbosity::
+
+    $ sudo crudini --set /var/lib/config-data/puppet-generated/nova/etc/nova/nova.conf DEFAULT debug false
+    $ sudo docker restart nova_scheduler
+
 Debugging container failures
 ----------------------------
 

doc/source/install/troubleshooting/troubleshooting-overcloud.rst

@@ -277,3 +277,5 @@ Each OpenStack service has now its own Debug parameter.
 
 Glance was an example, but all OpenStack services are supported. You can find their Debug
 in the TripleO Heat Templates composable services.
+
+It is also possible to :ref:`toggle debug<toggle_debug>` for services after deployment.