79 lines
3.3 KiB
ReStructuredText
79 lines
3.3 KiB
ReStructuredText
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=========
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Telemetry
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=========
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[TODO (Add Telemetry overview)]
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Telemetry central agent
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~~~~~~~~~~~~~~~~~~~~~~~
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The Telemetry central agent can be configured to partition its polling
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workload between multiple agents, enabling high availability.
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Both the central and the compute agent can run in an HA deployment,
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which means that multiple instances of these services can run in
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parallel with workload partitioning among these running instances.
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The `Tooz <https://pypi.python.org/pypi/tooz>`__ library provides
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the coordination within the groups of service instances.
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It provides an API above several back ends that can be used for building
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distributed applications.
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Tooz supports
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`various drivers <http://docs.openstack.org/developer/tooz/drivers.html>`__
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including the following back end solutions:
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* `Zookeeper <http://zookeeper.apache.org/>`__.
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Recommended solution by the Tooz project.
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* `Redis <http://redis.io/>`__.
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Recommended solution by the Tooz project.
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* `Memcached <http://memcached.org/>`__.
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Recommended for testing.
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You must configure a supported Tooz driver for the HA deployment of
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the Telemetry services.
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For information about the required configuration options that have
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to be set in the :file:`ceilometer.conf` configuration file for both
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the central and compute agents, see the `coordination section
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<http://docs.openstack.org/liberty/config-reference/content/
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ch_configuring-openstack-telemetry.html>`__
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in the OpenStack Configuration Reference.
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.. note:: Without the ``backend_url`` option being set only one
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instance of both the central and compute agent service is able to run
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and function correctly.
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The availability check of the instances is provided by heartbeat messages.
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When the connection with an instance is lost, the workload will be
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reassigned within the remained instances in the next polling cycle.
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.. note:: Memcached uses a timeout value, which should always be set to
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a value that is higher than the heartbeat value set for Telemetry.
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For backward compatibility and supporting existing deployments, the central
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agent configuration also supports using different configuration files for
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groups of service instances of this type that are running in parallel.
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For enabling this configuration, set a value for the partitioning_group_prefix
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option in the `central section <http://docs.openstack.org/liberty/
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config-reference/content/ch_configuring-openstack-telemetry.html>`__
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in the OpenStack Configuration Reference.
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.. warning:: For each sub-group of the central agent pool with the same
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``partitioning_group_prefix`` a disjoint subset of meters must be polled --
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otherwise samples may be missing or duplicated. The list of meters to poll
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can be set in the :file:`/etc/ceilometer/pipeline.yaml` configuration file.
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For more information about pipelines see the `Data collection and
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processing
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<http://docs.openstack.org/admin-guide-cloud/telemetry-data-collection.html#data-collection-and-processing>`__
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section.
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To enable the compute agent to run multiple instances simultaneously with
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workload partitioning, the workload_partitioning option has to be set to
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``True`` under the `compute section <http://docs.openstack.org/liberty/
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config-reference/content/ch_configuring-openstack-telemetry.html>`__
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in the :file:`ceilometer.conf` configuration file.
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