81 lines
3.3 KiB
ReStructuredText
81 lines
3.3 KiB
ReStructuredText
==========================
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Highly available Telemetry
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==========================
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The `Telemetry service
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<https://docs.openstack.org/admin-guide/common/get-started-telemetry.html>`_
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provides a data collection service and an alarming service.
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Telemetry polling agent
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~~~~~~~~~~~~~~~~~~~~~~~
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The Telemetry polling agent can be configured to partition its polling
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workload between multiple agents. This enables high availability (HA).
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Both the central and the compute agent can run in an HA deployment.
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This 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.org/project/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 <https://docs.openstack.org/tooz/latest/user/drivers.html>`_
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including the following back end solutions:
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* `Zookeeper <https://zookeeper.apache.org/>`_:
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Recommended solution by the Tooz project.
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* `Redis <https://redis.io/>`_:
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Recommended solution by the Tooz project.
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* `Memcached <https://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
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to set in the :file:`ceilometer.conf`, see the `coordination section
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<https://docs.openstack.org/ocata/config-reference/telemetry.html>`_
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in the OpenStack Configuration Reference.
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.. note::
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Only one instance for the central and compute agent service(s) is able
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to run and function correctly if the ``backend_url`` option is not set.
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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 remaining instances in the next polling cycle.
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.. note::
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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 supports using different configuration files. This is for
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groups of service instances that are running in parallel.
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For enabling this configuration, set a value for the
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``partitioning_group_prefix`` option in the
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`polling section <https://docs.openstack.org/ocata/config-reference/telemetry/telemetry-config-options.html>`_
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in the OpenStack Configuration Reference.
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.. warning::
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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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to avoid samples being 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 processing and pipelines
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<https://docs.openstack.org/admin-guide/telemetry-data-pipelines.html>`_
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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 must be set to
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``True`` under the `compute section <https://docs.openstack.org/ocata/config-reference/telemetry.html>`_
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in the :file:`ceilometer.conf` configuration file.
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