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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 5. Dynamic resolution using the PipeBackend</title><link rel="stylesheet" href="docbook.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="PowerDNS manual" /><link rel="up" href="index.html" title="PowerDNS manual" /><link rel="prev" href="configuring-db-connection.html" title="Chapter 4. Basic setup: configuring database connectivity" /><link rel="next" href="monitoring.html" title="Chapter 6. Logging & Monitoring Authoritative Server performance" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 5. Dynamic resolution using the PipeBackend</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="configuring-db-connection.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="monitoring.html">Next</a></td></tr></table><hr /></div><div class="chapter" title="Chapter 5. Dynamic resolution using the PipeBackend"><div class="titlepage"><div><div><h2 class="title"><a id="pipebackend-dynamic-resolution"></a>Chapter 5. Dynamic resolution using the PipeBackend</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="pipebackend-dynamic-resolution.html#pipe-and-bind">1. Deploying the PipeBackend with the BindBackend</a></span></dt></dl></div><p>
Also included in the PDNS distribution is the PipeBackend. The PipeBackend is primarily meant for
allowing rapid development of new backends without tight integration with PowerDNS. It allows
end-users to write PDNS backends in any language. A perl sample is provided.
The PipeBackend is also very well suited for dynamic resolution of queries. Example applications include
DNS based load balancing, geo-direction, DNS based failover with low TTLs.
</p><p>
The Pipe Backend also has a separate chapter in the backends appendix, see <a class="xref" href="backends-detail.html#pipebackend" title="1. PipeBackend">Section 1, “PipeBackend”</a>.
</p><p>
</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="note.png" /></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>
The Pipe Backend currently does not function under FreeBSD 4.x and 5.x, probably due to unfavorable interactions between
its threading implementation and the fork system call.
</p><p>
Interestingly, the Linux PowerDNS binary running under the Linuxulator on FreeBSD does work.
</p></td></tr></table></div><p>
</p><div class="sect1" title="1. Deploying the PipeBackend with the BindBackend"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="pipe-and-bind"></a>1. Deploying the PipeBackend with the BindBackend</h2></div></div></div><p>
Included with the PDNS distribution is the example.pl backend which has knowledge of the example.com zone, just like
the BindBackend. To install both, add the following to your <code class="filename">pdns.conf</code>:
</p><pre class="screen">
launch=pipe,bind
bind-example-zones
pipe-command=location/of/backend.pl
</pre><p>
Please adjust the <span class="command"><strong>pipe-command</strong></span> statement to the location of the unpacked PDNS distribution. If your backend is slow,
raise <span class="command"><strong>pipe-timeout</strong></span> from its default of 2000ms.
Now launch PDNS in monitor mode, and perform some queries. Note the difference with the earlier experiment where only the
BindBackend was loaded. The PipeBackend is launched first and thus gets queried first.
The sample backend.pl script knows about:
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
webserver.example.com A records pointing to 1.2.3.4, 1.2.3.5, 1.2.3.6
</p></li><li class="listitem"><p>
www.example.com CNAME pointing to webserver.example.com
</p></li><li class="listitem"><p>
MBOXFW (mailbox forward) records pointing to powerdns@example.com.
See the smtpredir documentation for information about MBOXFW.
</p></li></ul></div><p>
For more information about how to write exciting backends with the PipeBackend, see <a class="xref" href="backends-detail.html#pipebackend" title="1. PipeBackend">Section 1, “PipeBackend”</a>.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="configuring-db-connection.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="monitoring.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 4. Basic setup: configuring database connectivity </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 6. Logging & Monitoring Authoritative Server performance</td></tr></table></div></body></html>
