<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Dynamic resolution using the PipeBackend</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REL="HOME"
TITLE="PowerDNS manual"
HREF="index.html"><LINK
REL="PREVIOUS"
TITLE="Configure database connectivity"
HREF="configuring-db-connection.html"><LINK
REL="NEXT"
TITLE="Logging & Monitoring Authoritative Server performance"
HREF="monitoring.html"></HEAD
><BODY
CLASS="CHAPTER"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>PowerDNS manual</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="configuring-db-connection.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="monitoring.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="CHAPTER"
><H1
><A
NAME="PIPEBACKEND-DYNAMIC-RESOLUTION"
></A
>Chapter 5. Dynamic resolution using the PipeBackend</H1
><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 loadbalancing, geo-direction, DNS based failover with low TTLs.
</P
><P
> The Pipe Backend also has a separate chapter in the backends appendix, see <A
HREF="backends-detail.html#PIPEBACKEND"
>Section A.1</A
>.
</P
><P
> <DIV
CLASS="NOTE"
><P
></P
><TABLE
CLASS="NOTE"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="../images/note.gif"
HSPACE="5"
ALT="Note"></TD
><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
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="PIPE-AND-BIND"
>5.1. Deploying the PipeBackend with the BindBackend</A
></H1
><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 <TT
CLASS="FILENAME"
>pdns.conf</TT
>:
<PRE
CLASS="SCREEN"
> launch=pipe,bind
bind-example-zones
pipe-command=location/of/backend.pl
</PRE
>
Please adjust the <B
CLASS="COMMAND"
>pipe-command</B
> statement to the location of the unpacked PDNS distribution. If your backend is slow,
raise <B
CLASS="COMMAND"
>pipe-timeout</B
> 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
></P
><UL
><LI
><P
> webserver.example.com A records pointing to 1.2.3.4, 1.2.3.5, 1.2.3.6
</P
></LI
><LI
><P
> www.example.com CNAME pointing to webserver.example.com
</P
></LI
><LI
><P
> MBOXFW (mailbox forward) records pointing to powerdns@example.com.
See the smtpredir documentation for information about MBOXFW.
</P
></LI
></UL
>
For more information about how to write exciting backends with the PipeBackend, see Appendix A.
</P
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="configuring-db-connection.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="monitoring.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Configure database connectivity</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
> </TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Logging & Monitoring Authoritative Server performance</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
