81 lines
3.8 KiB
XML
81 lines
3.8 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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version="5.0"
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xml:id="metering-service">
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<title>Telemetry module</title>
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<para>The Telemetry module performs the following functions:</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>Efficiently polls metering data related to OpenStack
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services.</para>
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</listitem>
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<listitem>
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<para>Collects event and metering data by monitoring notifications
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sent from services.</para>
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</listitem>
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<listitem>
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<para>Publishes collected data to various targets including data
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stores and message queues.</para>
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</listitem>
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<listitem>
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<para>Creates alarms when collected data breaks defined rules.</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>The Telemetry module consists of the following
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components:</para>
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<variablelist>
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<varlistentry><term>A compute agent (<systemitem class="service"
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>ceilometer-agent-compute</systemitem>)</term>
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<listitem><para>Runs on each compute node and polls for resource
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utilization statistics. There may be other types of agents in the
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future, but for now our focus is creating the compute agent.</para>
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</listitem>
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</varlistentry>
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<varlistentry><term>A central agent (<systemitem class="service"
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>ceilometer-agent-central</systemitem>)</term>
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<listitem><para>Runs on a central management server to poll for
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resource utilization statistics for resources not tied to instances
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or compute nodes. Multiple agents can be started to scale service
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horizontally.</para></listitem>
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</varlistentry>
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<varlistentry><term>A notification agent (<systemitem class="service"
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>ceilometer-agent-notification</systemitem>)</term>
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<listitem><para>Runs on a central management server(s) and consumes
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messages from the message queue(s) to build event and metering data.
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</para></listitem>
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</varlistentry>
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<varlistentry><term>A collector (<systemitem class="service"
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>ceilometer-collector</systemitem>)</term>
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<listitem><para>Runs on central management server(s) and dispatches
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collected telemetry data to a data store or external consumer
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without modification.</para>
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</listitem>
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</varlistentry>
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<varlistentry><term>An alarm evaluator (<systemitem class="service"
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>ceilometer-alarm-evaluator</systemitem>)</term>
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<listitem><para>Runs on one or more central management servers to
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determine when alarms fire due to the associated statistic
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trend crossing a threshold over a sliding time window.</para></listitem>
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</varlistentry>
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<varlistentry><term>An alarm notifier (<systemitem class="service"
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>ceilometer-alarm-notifier</systemitem>)</term>
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<listitem><para>Runs on one or more central management servers to
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allow alarms to be set based on the threshold evaluation for a
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collection of samples.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>An API server (<systemitem
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class="service">ceilometer-api</systemitem>)</term>
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<listitem><para>Runs on one or more central management servers to
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provide data access from the data store.</para></listitem>
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</varlistentry>
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</variablelist>
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<para>These services communicate by using the OpenStack messaging bus.
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Only the collector and API server have access
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to the data store.</para>
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</section>
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