83 lines
3.8 KiB
XML
83 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 collects the metering data about the CPU
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and network costs.</para>
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</listitem>
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<listitem>
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<para>Collects data by monitoring notifications sent from
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services or by polling the infrastructure.</para>
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</listitem>
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<listitem>
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<para>Configures the type of collected data to meet
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various operating requirements. It accesses and inserts the
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metering data through the REST API.</para>
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</listitem>
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<listitem>
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<para>Expands the framework to collect custom usage data
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by additional plug-ins.</para>
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</listitem>
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<listitem>
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<para>Produces signed metering messages that cannot be
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repudiated.</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.</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) to monitor the
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message queues (for notifications and for metering data coming from
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the agent). Notification messages are processed and turned into
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metering messages, which are sent to the message bus using the
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appropriate topic. Telemetry messages are written to the data store
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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 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>A data store</term>
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<listitem><para>A database capable of handling
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concurrent writes (from one or more collector instances)
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and reads (from the API server).</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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