Support disabling Monasca alerting pipeline

The Monasca alerting pipeline provides multi-tenancy alerts and
notifications. It runs as an Apache Storm topology and generally
places a significant memory and CPU burden on monitoring hosts,
particularly when there are lot of metrics. This is fine if the
alerting service is in use, but sometimes it is not. For example
you may use Prometheus for monitoring the control plane, and
wish to offer tenants a monitoring service via Monasca without
alerting and notification functionality. In this case it makes
sense to disable this part of the Monasca pipeline and this patch
adds support for that.

If the service is ever re-enabled, all alerts and notifications
should spawn back automatically since they are persisted in the
central mysql database cluster.

Change-Id: I84aa04125c621712f805f41c8efbc92c8e156db9

ansible/group_vars/all.yml

@@ -673,7 +673,7 @@ enable_sahara: "no"
 enable_senlin: "no"
 enable_skydive: "no"
 enable_solum: "no"
-enable_storm: "{{ enable_monasca | bool }}"
+enable_storm: "{{ enable_monasca | bool and monasca_enable_alerting_pipeline | bool }}"
 enable_swift: "no"
 enable_swift_s3api: "no"
 enable_swift_recon: "no"
@@ -707,6 +707,8 @@ enable_destroy_images: "no"
 ####################
 # Monasca options
 ####################
+monasca_enable_alerting_pipeline: True
+
 monasca_api_admin_base_endpoint: "{{ admin_protocol }}://{{ kolla_internal_fqdn  | put_address_in_context('url') }}:{{ monasca_api_port }}"
 monasca_api_internal_base_endpoint: "{{ internal_protocol }}://{{ kolla_internal_fqdn  | put_address_in_context('url') }}:{{ monasca_api_port }}"
 monasca_api_public_base_endpoint: "{{ public_protocol }}://{{ kolla_external_fqdn  | put_address_in_context('url') }}:{{ monasca_api_port }}"

ansible/monasca_cleanup.yml

@@ -12,3 +12,11 @@
   roles:
     - { role: monasca,
         tags: monasca }
+
+- name: Cleanup unused Storm services
+  hosts:
+    - storm-worker
+    - storm-nimbus
+  roles:
+    - { role: storm,
+        tags: storm }

ansible/roles/monasca/defaults/main.yml

@@ -46,14 +46,14 @@ monasca_services:
   monasca-thresh:
     container_name: monasca_thresh
     group: monasca-thresh
-    enabled: true
+    enabled: "{{ monasca_enable_alerting_pipeline | bool }}"
     image: "{{ monasca_thresh_image_full }}"
     volumes: "{{ monasca_thresh_default_volumes + monasca_thresh_extra_volumes }}"
     dimensions: "{{ monasca_thresh_dimensions }}"
   monasca-notification:
     container_name: monasca_notification
     group: monasca-notification
-    enabled: true
+    enabled: "{{ monasca_enable_alerting_pipeline | bool }}"
     image: "{{ monasca_notification_image_full }}"
     volumes: "{{ monasca_notification_default_volumes + monasca_notification_extra_volumes }}"
     dimensions: "{{ monasca_notification_dimensions }}"
@@ -186,23 +186,23 @@ monasca_all_topics:
   - name: "{{ monasca_events_topic }}"
     partitions: "{{ monasca_default_topic_partitions }}"
     replication_factor: "{{ monasca_default_topic_replication_factor }}"
-    enabled: True
+    enabled: "{{ monasca_enable_alerting_pipeline | bool }}"
   - name: "{{ monasca_alarm_state_transitions_topic }}"
     partitions: "{{ monasca_default_topic_partitions }}"
     replication_factor: "{{ monasca_default_topic_replication_factor }}"
-    enabled: True
+    enabled: "{{ monasca_enable_alerting_pipeline | bool }}"
   - name: "{{ monasca_alarm_notifications_topic }}"
     partitions: "{{ monasca_default_topic_partitions }}"
     replication_factor: "{{ monasca_default_topic_replication_factor }}"
-    enabled: True
+    enabled: "{{ monasca_enable_alerting_pipeline | bool }}"
   - name: "{{ monasca_alarm_notifications_retry_topic }}"
     partitions: "{{ monasca_default_topic_partitions }}"
     replication_factor: "{{ monasca_default_topic_replication_factor }}"
-    enabled: True
+    enabled: "{{ monasca_enable_alerting_pipeline | bool }}"
   - name: "{{ monasca_periodic_notifications_topic }}"
     partitions: "{{ monasca_default_topic_partitions }}"
     replication_factor: "{{ monasca_default_topic_replication_factor }}"
-    enabled: True
+    enabled: "{{ monasca_enable_alerting_pipeline | bool }}"
 
 # NOTE(dszumski): Due to the way monasca-notification is currently
 # implemented it is not recommended to change this period.

ansible/roles/monasca/templates/monasca-persister/persister.conf.j2

@@ -15,9 +15,13 @@ port = {{ monasca_influxdb_http_port }}
 legacy_kafka_client_enabled = False
 
 [kafka_alarm_history]
+{% if not monasca_enable_alerting_pipeline | bool %}
+enabled = False
+{% else %}
 uri = {{ monasca_kafka_servers }}
 topic = {{ monasca_alarm_state_transitions_topic }}
 num_processors = 1
+{% endif %}
 
 [kafka_metrics]
 uri = {{ monasca_kafka_servers }}

ansible/roles/storm/defaults/main.yml

@@ -5,7 +5,7 @@ storm_services:
   storm-worker:
     container_name: storm_worker
     group: storm-worker
-    enabled: true
+    enabled: "{{ enable_storm | bool }}"
     image: "{{ storm_image_full }}"
     environment:
       STORM_LOG_DIR: /var/log/kolla/storm
@@ -15,7 +15,7 @@ storm_services:
   storm-nimbus:
     container_name: storm_nimbus
     group: storm-nimbus
-    enabled: true
+    enabled: "{{ enable_storm | bool }}"
     image: "{{ storm_image_full }}"
     environment:
       STORM_LOG_DIR: /var/log/kolla/storm

ansible/roles/storm/tasks/cleanup.yml

@@ -0,0 +1,22 @@
+---
+- name: Stop and remove containers for Storm services
+  become: true
+  kolla_docker:
+    action: "stop_and_remove_container"
+    name: "{{ item.value.container_name }}"
+  when:
+    - inventory_hostname in groups[item.value.group]
+    - not item.value.enabled | bool
+  with_dict: "{{ storm_services }}"
+
+- name: Removing config for any disabled services
+  file:
+    path: "{{ node_config_directory }}/{{ item.key }}"
+    state: "absent"
+  become: true
+  when:
+    - inventory_hostname in groups[item.value.group]
+    - not item.value.enabled | bool
+  with_dict: "{{ storm_services }}"
+
+# NOTE(dszumski): Docker volume removal is currently a manual procedure

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

@@ -42,6 +42,13 @@ Enable Monasca in ``/etc/kolla/globals.yml``:
 
    enable_monasca: "yes"
 
+If you wish to disable the alerting and notification pipeline to reduce
+resource usage you can set ``/etc/kolla/globals.yml``:
+
+.. code-block:: yaml
+
+   monasca_enable_alerting_pipeline: "no"
+
 Currently Monasca is only supported using the ``source`` install type Kolla
 images. If you are using the ``binary`` install type you should set the
 following override in ``/etc/kolla/globals.yml``:
@@ -334,6 +341,9 @@ which you must run the cleanup command is given below:
   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.
+- If you have disabled the alerting pipeline via the
+  `monasca_enable_alerting_pipeline` flag after you have deployed the alerting
+  services.
 
 The cleanup command can be invoked from the Kolla Ansible CLI, for example:
 
@@ -365,7 +375,7 @@ System requirements and performance impact
 Monasca will deploy the following Docker containers:
 
 * Apache Kafka
-* Apache Storm
+* Apache Storm (optional)
 * Apache Zookeeper
 * Elasticsearch
 * Grafana
@@ -378,9 +388,9 @@ Monasca will deploy the following Docker containers:
 * Monasca Log API
 * Monasca Log Metrics (Logstash, optional, deprecated)
 * Monasca Log Persister (Logstash)
-* Monasca Notification
+* Monasca Notification (optional)
 * Monasca Persister
-* Monasca Thresh (Apache Storm topology)
+* Monasca Thresh (Apache Storm topology, optional)
 
 In addition to these, Monasca will also utilise Kolla deployed MariaDB,
 Keystone, Memcached and HAProxy/Keepalived. The Monasca Agent containers
@@ -397,6 +407,10 @@ multi-core CPU. You will also need enough space to store metrics and logs,
 and to buffer these in Kafka. Whilst Kafka is happy with spinning disks,
 you will likely want to use SSDs to back InfluxDB and Elasticsearch.
 
+If resources are tight, it is possible to disable the alerting and
+notification pipeline which removes the need for Apache Storm, Monasca
+Thresh and Monasca Notification. This can have a significant effect.
+
 .. _Security impact:
 
 Security impact

releasenotes/notes/support-disabling-monasca-alerting-service-92d49ead068447f8.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Support has been added to optionally disable the Monasca alerting
+    pipeline. This can be helpful to reduce resource consumption on
+    Monasca service hosts if the alerting pipeline is not in use.