Hosting Provided By

Re: two bind9 masters

From: Craig Sanders <cas(at)taz.net.au>
Date: Thu Oct 11 2007 - 17:17:45 EDT

On Thu, Oct 11, 2007 at 12:46:06PM -0400, Dan MacNeil wrote:
> We decided not to use bind's replication mechanism because it required us
> to add zones to each server by hand.

so?

more to the point, it didn't "require" you to add zones by hand, you chose to do that because you weren't sufficiently lazy :-)

laziness is a virtue because it motivates you to do things the smart easy way rather than the hard dumb way.

> For example in our named.inc
>
> zone "lbgc.org" {
> type master;
> file "db.lbgc";
> };

do you realise how trivially easy it is to generate config fragments like that?

this is part of what perl (and sh and other scripting languages) are FOR - to automate generation of repetitive and tedious config fragments like bind config, apache virtualhost config, mailing list config, etc etc etc.

for a primary zone, the only thing that differs is the zone name and maybe the file name (although the filename can be the same as the zone name or derived from it).

Do you need help?

for a secondary, the only things that change are the zone name and the master server's IP to secondary it from.

so, a text file like this:

master master1.example.com
master master2.example.com

    secondary sec1.example.com 192.168.1.1
    secondary sec2.example.com 192.168.1.1
    secondary sec3.example.com 172.31.1.1

(or you can skip the first word if you have one text file for masters and another text file for secondaries - in fact, if you secondary for several other ISPs you could have one secondary file per ISP. or it could be pulled out of a database)

with a trivial line perl script could generate a named config file which could be included into named.conf.

the script would look something like the one below. it's trivial - i wrote it from scratch for this email, with just the memory of doing something similar years ago to guide me.

it's written as a filter. input on stdin, output on stdout. redirect as needed. most of my systems automation scripts are written that way - i find it far more useful and flexible than hard-coding input and output filenames...and allows easy testing of changes by piping output into less or to a /tmp/ file.

#! /usr/bin/perl

Do you need more help?

$Default_Primary_IP = '192.168.1.1';

while (<>) {

	chomp;
	s/#.*//;
	next if (/^$/);
	
	my ($Type, $Zone, $ZSource) = split ;

	if ($Type =~ /^(master|primary)$/io) {

		# Zone filename defaults to same as Zone if blank
        $ZSource = $Zone if ($ZSource eq '') ;
		print <<__EOF__;

zone "$Zone" {
	type master;
	file "$ZSource";

};
__EOF__

	} elsif ($Type =~ /^(secondary|slave)/io) {
		# Use default primary IP if ZSource is blank
		$ZSource = $Default_Primary_IP if ($ZSource eq '');

		print <<__EOF__;

zone "$Zone" {
	type slave;
	file "$Zone";
    masters {
		$ZSource;
	} ;

};
__EOF__ };
};

NOTE: untested but It Should Work<tm>. there may be minor syntactic errors because i wrote it without referring to any documentation - in particular, i can never remember whether it's 'eq' or '==' for comparing strings until i look it up in the perlop man page.

a script like this, combined with a Makefile to automate the generation (and scp-ing or rsync-ing of files) when the source text files have changed can completely automate management of DNS zones - and even automatically check in changes to a revision control system like RCS or Subversion.

in fact, subversion can serve a double use as the delivery mechanism to get updates to other machines. check-in the files on one machine, check them out on others. then you can edit the files on any of the machines and know that the changes will be replicated to all the others. i have used this technique to replicate my (generated) apache virtual host config from one load-balanced web server to others in the same load-balanced web farm.

once the automation scripts are written and tested, updating things is as simple as editing one small text file and running "make" - the Makefile automates everything, and does everything else in precisely the correct order.

craig

-- 
craig sanders 

Other than that, Mrs. Lincoln, how did you like the play?


-- 
To UNSUBSCRIBE, email to debian-isp-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org

Received on Thu Oct 11 17:28:13 2007

This message: [ Message body ]
Next message: Eric Hudspeth: "Re: two bind9 masters"
Previous message: Dan MacNeil: "Re: two bind9 masters"
In reply to: Dan MacNeil: "Re: two bind9 masters"
Next in thread: Dominique Görsch: "Re: two bind9 masters"

Contemporary messages sorted: [ By Date ] [ By Thread ] [ By Subject ] [ By Author ] [ By messages with attachments ]

This archive was generated by hypermail 2.1.8 : Wed Mar 19 2008 - 06:51:05 EDT

Can we help you?