openstack-manuals/doc/admin-guide-cloud/telemetry/section_telemetry-system-architecture.xml

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  xml:id="section_telemetry-system-architecture">
  <title>System architecture</title>
  <para>The Telemetry module uses an agent-based architecture.
    Several modules combine their responsibilities to collect data,
    store samples in a database, or provide an API service for handling
    incoming requests.</para>
  <para>The Telemetry module is built from the following agents and
    services:</para>
  <para>
    <variablelist>
      <varlistentry>
        <term><systemitem class="service">ceilometer-api</systemitem></term>
          <listitem>
              <para>Presents aggregated metering data to consumers
                (such as billing engines, analytics tools and so forth).</para>
          </listitem>
      </varlistentry>
      <varlistentry>
        <term><systemitem class="service">ceilometer-agent-central</systemitem></term>
          <listitem>
            <para>Polls the public RESTful APIs of other OpenStack
              services such as Compute service and Image service, in order to
              keep tabs on resource existence.</para>
          </listitem>
      </varlistentry>
      <varlistentry>
        <term><systemitem class="service">ceilometer-agent-compute</systemitem></term>
          <listitem>
            <para>Polls the local hypervisor or libvirt daemon to acquire
              performance data for the local instances, messages and emits these
              data as AMQP messages.</para>
          </listitem>
      </varlistentry>
      <varlistentry>
        <term><systemitem class="service">ceilometer-agent-notification</systemitem></term>
          <listitem>
            <para>Consumes AMQP messages from other OpenStack services.</para>
          </listitem>
      </varlistentry>
      <varlistentry>
        <term><systemitem class="service">ceilometer-agent-ipmi</systemitem></term>
          <listitem>
            <para>Polls compute node with IPMI support, in order to
              acquire IPMI sensor data and Intel Node Manager data.</para>
          </listitem>
      </varlistentry>
      <varlistentry>
        <term><systemitem class="service">ceilometer-collector</systemitem></term>
          <listitem>
            <para>Consumes AMQP notifications from the agents, then dispatches
              these data to the metering store.</para>
          </listitem>
      </varlistentry>
      <varlistentry>
        <term><systemitem class="service">ceilometer-alarm-evaluator</systemitem></term>
          <listitem>
            <para>Determines when alarms fire due to the associated statistic
              trend crossing a threshold over a sliding time window.</para>
          </listitem>
      </varlistentry>
      <varlistentry>
        <term><systemitem class="service">ceilometer-alarm-notifier</systemitem></term>
          <listitem>
            <para>Initiates alarm actions, for example calling out to a webhook
              with a description of the alarm state transition.</para>
          </listitem>
      </varlistentry>
    </variablelist>
  </para>
  <para>Besides the <systemitem class="service">ceilometer-agent-compute</systemitem> service,
    all the other services are placed on one or more controller nodes.</para>
  <para>The Telemetry architecture highly depends on the AMQP service both for consuming
    notifications coming from OpenStack services and internal communication.</para>
  <section xml:id="section_telemetry-supported-dbs">
    <title>Supported databases</title>
    <para>The other key external component of Telemetry is the database, where the samples, alarm
      definitions and alarms are stored.</para>
    <note>
      <para>Multiple database back ends can be configured in order to store samples and alarms
        separately.</para>
    </note>
    <para>The list of supported database back ends:</para>
    <para>
      <itemizedlist>
        <listitem>
          <para><link xlink:href="http://www.mongodb.org/">MongoDB</link></para>
        </listitem>
        <listitem>
          <para><link xlink:href="http://www.mysql.com/">MySQL</link></para>
        </listitem>
        <listitem>
          <para><link xlink:href="http://www.postgresql.org/">PostgreSQL</link></para>
        </listitem>
        <listitem>
          <para><link xlink:href="http://hbase.apache.org/">HBase</link></para>
        </listitem>
        <listitem>
          <para><link xlink:href="http://www-01.ibm.com/software/data/db2/">DB2</link>
          </para>
        </listitem>
      </itemizedlist>
    </para>
  </section>
  <section xml:id="section_telemetry-supported-hypervisors">
    <title>Supported hypervisors</title>
    <para>The Telemetry module collects information about the virtual machines, which requires
      close connection to the hypervisor that runs on the compute hosts.</para>
    <para>The list of supported hypervisors is:</para>
    <para>
      <itemizedlist>
        <listitem>
          <para>The following hypervisors are supported via
            <link xlink:href="http://libvirt.org/">Libvirt</link>:</para>
          <itemizedlist>
            <listitem>
              <para>
                <link xlink:href="http://www.linux-kvm.org/page/Main_Page">Kernel-based
                 Virtual Machine (KVM)</link>
              </para>
            </listitem>
            <listitem>
              <para>
                <link xlink:href="http://wiki.qemu.org/Main_Page">Quick Emulator (QEMU)</link>
              </para>
            </listitem>
            <listitem>
              <para>
                <link xlink:href="https://linuxcontainers.org/">Linux Containers (LXC)</link>
              </para>
            </listitem>
            <listitem>
              <para>
                <link xlink:href="http://www.xenproject.org/help/documentation.html">XEN</link>
              </para>
            </listitem>
            <listitem>
              <para>
                <link xlink:href="http://user-mode-linux.sourceforge.net/">
                User-mode Linux (UML)</link>
              </para>
            </listitem>
          </itemizedlist>
          <note>
            <para>For details about hypervisor support in Libvirt please check the
              <link xlink:href="http://libvirt.org/hvsupport.html">Libvirt API
              support matrix</link>.
            </para>
          </note>
        </listitem>
        <listitem>
          <para><link
            xlink:href="http://www.microsoft.com/en-us/server-cloud/hyper-v-server/default.aspx"
            >Hyper-V</link>
          </para>
        </listitem>
        <listitem>
          <para><link
            xlink:href="http://www.vmware.com/products/vsphere-hypervisor/support.html"
            >VMWare vSphere</link>
          </para>
        </listitem>
      </itemizedlist>
    </para>
  </section>
  <section xml:id="section_telemetry-supported-networking-services">
    <title>Supported networking services</title>
    <para>Telemetry is able to retrieve information from OpenStack Networking
      and external networking services:</para>
    <para>
      <itemizedlist>
        <listitem>
          <para>OpenStack Networking:
            <itemizedlist>
              <listitem>
                <para>Basic network metrics</para>
              </listitem>
              <listitem>
                <para>Firewall-as-a-Service (FWaaS) metrics</para>
              </listitem>
              <listitem>
                <para>Loadbalancer-as-a-Service (LBaaS) metrics</para>
              </listitem>
              <listitem>
                <para>VPN-as-a-Service (VPNaaS) metrics</para>
              </listitem>
            </itemizedlist>
          </para>
        </listitem>
        <listitem>
          <para>SDN controller metrics:
            <itemizedlist>
              <listitem>
                <para><link xlink:href="http://www.opendaylight.org/software">
                  OpenDaylight</link></para>
              </listitem>
              <listitem>
                <para><link xlink:href="http://opencontrail.org/">OpenContrail</link></para>
              </listitem>
            </itemizedlist>
          </para>
        </listitem>
      </itemizedlist>
    </para>
  </section>
  <section xml:id="section_telemetry-users-roles">
    <title>Users, roles and tenants</title>
    <para>This module of OpenStack uses OpenStack Identity for authenticating and authorizing
      users. The required configuration options are listed in the <link xlink:href=
      "http://docs.openstack.org/trunk/config-reference/content/ch_configuring-openstack-telemetry.html">
      Telemetry section</link> in the <citetitle>OpenStack Configuration Reference</citetitle>.</para>
    <para>Two roles are used in the system basically, which are the 'admin' and 'non-admin'. The
      authorization happens before processing each API request. The amount of returned data depends
      on the role the requestor owns.</para>
    <para>The creation of alarm definitions also highly depends on the role of the user, who
      initiated the action. Further details about alarm handling can be found in
      <xref linkend="section_telemetry-alarms"/> in this guide.</para>
  </section>
</section>