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
Historically Monasca Log Transformer has been for log
standardisation and processing. For example, logs from different
sources may use slightly different error levels such as WARN, 5,
or WARNING. Monasca Log Transformer is a place where these could
be 'squashed' into a single error level to simplify log searches
based on labels such as these.
However, in Kolla Ansible, we do this processing in Fluentd so
that the simpler Fluentd -> Elastic -> Kibana pipeline also
benefits. This helps to avoid spreading out log parsing
configuration over many services, with the Fluentd Monasca output
plugin being yet another potential place for processing (which
should be avoided). It therefore makes sense to remove this
service entirely, and squash any existing configuration which
can't be moved to Fluentd into the Log Perister service. I.e.
by removing this pipeline, we don't loose any functionality,
we encourage log processing to take place in Fluentd, or at least
outside of Monasca, and we make significant gains in efficiency
by removing a topic from Kafka which contains a copy of all logs
in transit.
Finally, users forwarding logs from outside the control plane,
eg. from tenant instances, should be encouraged to process the
logs at the point of sending using whichever framework they are
forwarding them with. This makes sense, because all Logstash
configuration in Monasca is only accessible by control plane
admins. A user can't typically do any processing inside Monasca,
with or without this change.
Change-Id: I65c76d0d1cd488725e4233b7e75a11d03866095c
