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<p class="apache">Apache HTTP Server Version 2.4</p>
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<div id="preamble"><h1>Apache Module mod_heartmonitor</h1>
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<p><span>Available Languages: </span><a href="../en/mod/mod_heartmonitor.html" title="English">&nbsp;en&nbsp;</a> |
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Centralized monitor for mod_heartbeat origin servers</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="module-dict.html#ModuleIdentifier">Module&nbsp;Identifier:</a></th><td>heartmonitor_module</td></tr>
<tr><th><a href="module-dict.html#SourceFile">Source&nbsp;File:</a></th><td>mod_heartmonitor.c</td></tr>
<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3 and later</td></tr></table>
<h3>Summary</h3>

<p>
<code class="module"><a href="../mod/mod_heartmonitor.html">mod_heartmonitor</a></code> listens for server status messages generated
by <code class="module"><a href="../mod/mod_heartbeat.html">mod_heartbeat</a></code> enabled origin servers and makes their status
available to <code class="module"><a href="../mod/mod_lbmethod_heartbeat.html">mod_lbmethod_heartbeat</a></code>. This allows
<code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> to use the "heartbeat"
<em>lbmethod</em> inside of <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code>.
</p>

<p>This module uses the services of <code class="module"><a href="../mod/mod_slotmem_shm.html">mod_slotmem_shm</a></code> when
available instead of flat-file storage.  No configuration is required to
use <code class="module"><a href="../mod/mod_slotmem_shm.html">mod_slotmem_shm</a></code>.</p>

    <div class="warning">
        To use <code class="module"><a href="../mod/mod_heartmonitor.html">mod_heartmonitor</a></code>,
        <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> and <code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code>
        must be either a static modules or, if a dynamic module, it must
        be loaded before <code class="module"><a href="../mod/mod_heartmonitor.html">mod_heartmonitor</a></code>.
    </div>

</div>
<div id="quickview"><h3 class="directives">Directives</h3>
<ul id="toc">
<li><img alt="" src="../images/down.gif"> <a href="#heartbeatlisten">HeartbeatListen</a></li>
<li><img alt="" src="../images/down.gif"> <a href="#heartbeatmaxservers">HeartbeatMaxServers</a></li>
<li><img alt="" src="../images/down.gif"> <a href="#heartbeatstorage">HeartbeatStorage</a></li>
</ul>
<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&amp;list_id=144532&amp;product=Apache%20httpd-2&amp;query_format=specific&amp;order=changeddate%20DESC%2Cpriority%2Cbug_severity&amp;component=mod_heartmonitor">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&amp;component=mod_heartmonitor">Report a bug</a></li></ul></div>

<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="heartbeatlisten"><span id="HeartbeatListen">HeartbeatListen</span> Directive <a title="Permanent link" href="#heartbeatlisten" class="permalink">&para;</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>multicast address to listen for incoming heartbeat requests </td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HeartbeatListen <var>addr:port</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>disabled</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_heartmonitor</td></tr>
</table>
    <p>The <code class="directive">HeartbeatListen</code> directive specifies the
    multicast address on which the server will listen for status information from
    <code class="module"><a href="../mod/mod_heartbeat.html">mod_heartbeat</a></code>-enabled servers.  This
    address will usually correspond to a configured  <code class="directive"><a href="../mod/mod_heartbeat.html#heartbeataddress">HeartbeatAddress</a></code> on an origin server.
    </p>

    <pre class="prettyprint lang-config">HeartbeatListen 239.0.0.1:27999</pre>


    <p> This module is inactive until this directive is used.</p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="heartbeatmaxservers"><span id="HeartbeatMaxServers">HeartbeatMaxServers</span> Directive <a title="Permanent link" href="#heartbeatmaxservers" class="permalink">&para;</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Specifies the maximum number of servers that will be sending
heartbeat requests to this server</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HeartbeatMaxServers <var>number-of-servers</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HeartbeatMaxServers 10</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_heartmonitor</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The value of 0 is accepted only in 2.4.55 and above</td></tr>
</table>
    <p>The <code class="directive">HeartbeatMaxServers</code> directive specifies the
    maximum number of servers that will be sending requests to this monitor
    server.  It is used to control the size of the shared memory allocated
    to store the heartbeat info when <code class="module"><a href="../mod/mod_slotmem_shm.html">mod_slotmem_shm</a></code> is in use.</p>
    <p>Set this to <code>0</code> to use flat-file storage instead
    of shared memory (i.e., without loading
    <code class="module"><a href="../mod/mod_slotmem_shm.html">mod_slotmem_shm</a></code>). When using shared memory,
    the value must be 10 or greater.</p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="heartbeatstorage"><span id="HeartbeatStorage">HeartbeatStorage</span> Directive <a title="Permanent link" href="#heartbeatstorage" class="permalink">&para;</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Path to store heartbeat data when using flat-file storage</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HeartbeatStorage <var>file-path</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HeartbeatStorage logs/hb.dat</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_heartmonitor</td></tr>
</table>
    <p>The <code class="directive">HeartbeatStorage</code> directive specifies the
    path to store heartbeat data.  This flat-file is used only when
    <code class="module"><a href="../mod/mod_slotmem_shm.html">mod_slotmem_shm</a></code> is not loaded and
    <code class="directive"><a href="#heartbeatmaxservers">HeartbeatMaxServers</a></code> is set to 0.</p>

</div>
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