By default, Ceilometer consumes notifications on the messaging bus sent to topics by using a queue/pool name that is identical to the topic name. You shouldn’t have different applications consuming messages from this queue. If you want to also consume the topic notifications with a system other than Ceilometer, you should configure a separate queue that listens for the same messages.
Ceilometer allows multiple topics to be configured so that the polling agent can send the same messages of notifications to other queues. Notification agents also use topics to configure which queue to listen for. If you use multiple topics, you should configure notification agent and polling agent separately, otherwise Ceilometer collects duplicate samples.
By default, the ceilometer.conf file is as follows:
[oslo_messaging_notifications]
topics = notifications
To use multiple topics, you should give ceilometer-agent-notification and ceilometer-polling services different ceilometer.conf files. The Ceilometer configuration file ceilometer.conf is normally locate in the /etc/ceilometer directory. Make changes according to your requirements which may look like the following:
For notification agent using ceilometer-notification.conf, settings like:
[oslo_messaging_notifications]
topics = notifications,xxx
For polling agent using ceilometer-polling.conf, settings like:
[oslo_messaging_notifications]
topics = notifications,foo
Note
notification_topics in ceilometer-notification.conf should only have one same topic in ceilometer-polling.conf
Doing this, it’s easy to listen/receive data from multiple internal and external services.
The Ceilometer collector allows multiple dispatchers to be configured so that data can be easily sent to multiple internal and external systems. Dispatchers are divided between event_dispatchers and meter_dispatchers which can each be provided with their own set of receiving systems.
Note
In Liberty and prior, the configuration option for all data was dispatcher but this was changed for the Mitaka release to break out separate destination systems by type of data.
By default, Ceilometer only saves event and meter data in a database. If you want Ceilometer to send data to other systems, instead of or in addition to the Ceilometer database, multiple dispatchers can be enabled by modifying the Ceilometer configuration file.
Ceilometer ships multiple dispatchers currently. They are database, file, http and gnocchi dispatcher. As the names imply, database dispatcher sends metering data to a database, file dispatcher logs meters into a file, http dispatcher posts the meters onto a http target, gnocchi dispatcher posts the meters onto Gnocchi backend. Each dispatcher can have its own configuration parameters. Please see available configuration parameters at the beginning of each dispatcher file.
To check if any of the dispatchers is available in your system, you can inspect the Ceilometer egg entry_points.txt file, you should normally see text like the following:
[ceilometer.dispatcher]
database = ceilometer.dispatcher.database:DatabaseDispatcher
file = ceilometer.dispatcher.file:FileDispatcher
http = ceilometer.dispatcher.http:HttpDispatcher
gnocchi = ceilometer.dispatcher.gnocchi:GnocchiDispatcher
To configure one or multiple dispatchers for Ceilometer, find the Ceilometer configuration file ceilometer.conf which is normally located at /etc/ceilometer directory and make changes accordingly. Your configuration file can be in a different directory.
To use multiple dispatchers on a Ceilometer collector service, add multiple dispatcher lines in ceilometer.conf file like the following:
[DEFAULT]
meter_dispatchers=database
meter_dispatchers=file
If there is no dispatcher present, database dispatcher is used as the default. If in some cases such as traffic tests, no dispatcher is needed, one can configure the line without a dispatcher, like the following:
event_dispatchers=
With the above configuration, no event dispatcher is used by the Ceilometer collector service, all event data received by Ceilometer collector will be dropped.
For Gnocchi dispatcher, the following configuration settings should be added:
[DEFAULT]
meter_dispatchers = gnocchi
event_dispatchers = gnocchi
[dispatcher_gnocchi]
archive_policy = low
The value specified for archive_policy should correspond to the name of an archive_policy configured within Gnocchi.
For Gnocchi dispatcher backed by Swift storage, the following additional configuration settings should be added:
[dispatcher_gnocchi]
filter_project = gnocchi_swift
filter_service_activity = True
Note
If gnocchi dispatcher is enabled, Ceilometer api calls will return a 410 with an empty result. The Gnocchi Api should be used instead to access the data.