Disable Monasca Log Metrics service by default

The Log Metrics service is an admin only service. We now have
support in Fluentd via the Prometheus plugin to create metrics
from logs. These metrics can be scraped into Monasca or Prometheus.
It therefore makes sense to deprecate this service, starting by
disabling it by default, and then removing it in the Xena release.
This should improve the stability of the Monasca metrics pipeline
by ensuring that all metrics pass via the Monasca API for
validation, and ensure that metrics generated from logs are
available to both Prometheus and Monasca users by default.

Change-Id: I704feb4434c1eece3eb00c19dc5f934fd4bc27b4

Author: dougszumski

ansible/roles/monasca/defaults/main.yml

@@ -39,7 +39,7 @@ monasca_services:
   monasca-log-metrics:
     container_name: monasca_log_metrics
     group: monasca-log-metrics
-    enabled: true
+    enabled: "{{ monasca_enable_log_metrics_service | bool }}"
     image: "{{ monasca_logstash_image_full }}"
     volumes: "{{ monasca_log_metrics_default_volumes + monasca_log_metrics_extra_volumes }}"
     dimensions: "{{ monasca_log_metrics_dimensions }}"
@@ -125,6 +125,11 @@ monasca_influxdb_retention_policy:
 ####################
 # Monasca
 ####################
+
+# NOTE(dszumski): This can be removed in the Xena cycle when the
+# log metrics service is removed
+monasca_enable_log_metrics_service: False
+
 monasca_kafka_servers: "{% for host in groups['kafka'] %}{{ 'api' | kolla_address(host) | put_address_in_context('url') }}:{{ kafka_port }}{% if not loop.last %},{% endif %}{% endfor %}"
 monasca_zookeeper_servers: "{% for host in groups['zookeeper'] %}{{ 'api' | kolla_address(host) | put_address_in_context('url') }}:{{ zookeeper_client_port }}{% if not loop.last %},{% endif %}{% endfor %}"
 monasca_memcached_servers: "{% for host in groups['memcached'] %}{{ 'api' | kolla_address(host) | put_address_in_context('memcache') }}:{{ memcached_port }}{% if not loop.last %},{% endif %}{% endfor %}"

doc/source/reference/logging-and-monitoring/monasca-guide.rst

@@ -325,6 +325,11 @@ which you must run the cleanup command is given below:
 
 - Upgrading from Victoria to Wallaby to remove the unused Monasca Log
   Transformer service
+- Upgrading from Victoria to Wallaby to remove the Monasca Log Metrics
+  service, unless the option to disable it by default has been overridden in
+  Wallaby.
+- Upgrading from Wallaby to Xena to remove the Monasca Log Metrics service
+  if the option to disable it by default was overridden in Wallaby.
 
 The cleanup command can be invoked from the Kolla Ansible CLI, for example:
 
@@ -367,7 +372,7 @@ Monasca will deploy the following Docker containers:
 * Monasca Agent Statsd
 * Monasca API
 * Monasca Log API
-* Monasca Log Metrics (Logstash)
+* Monasca Log Metrics (Logstash, optional, deprecated)
 * Monasca Log Persister (Logstash)
 * Monasca Notification
 * Monasca Persister

releasenotes/notes/deprecate-monasca-log-metrics-service-d558015f1cf426df.yaml

@@ -0,0 +1,10 @@
+---
+upgrade:
+  - |
+    The Monasca Log Metrics service has been deprecated and is now
+    disabled by default. If you wish to enable it, you can set
+    `monasca_enable_log_metrics_service` to `True` in `globals.yml`.
+deprecations:
+  - |
+    The Monasca Log Metrics service has been deprecated and will be
+    removed in the Xena release.