WordPress MU and /etc/hosts file

Due to a silly networking problem originating from the LVS installation we’re using, we’re stuck with a setup in which machines in the DMZ cannot access themselves via their external addresses. This is a problem for several scripts which refer to their own URL when doing some maintenance. Especially with a certain WordPress MU installation managed by our friends from Interconnect IT, we ran into trouble when they tried to update their WordPress code.

Puppet to the rescue. Although not something I’m especially proud of, I can imagine other using this as an example to fix other problems. What we do is use the wp-config.php from the WordPress installation to get data from the database that WordPress MU connects to. We use a PHP script to retrieve that data and format it in a comma-separated-value list. We then use this output to create a Facter fact, which we use in puppet to create entries in the /etc/hosts file.

You could eliminate the bash scripting by making sure the PHP script copies the files and outputs in the correct format, but it’s been ages since I’ve written anything remotely PHPish, so I decided to only do the bare minimum in PHP and do the rest in bash. YMMV.

Now without further a-do, here’s the shell script we run:

#!/bin/sh

# We want to change to the directory where this script is installed.
OLDDIR=`pwd`
cd /opt/wp-domain

# Make sure we have an empty wp-settings.php, because wp-config.php includes
# it.
touch wp-settings.php

# Copy wp-config.php from the WordPress MU installation.
# CHANGEME You want to change this path, I'm sure...
cp /srv/www/wordpress-mu/wp-config.php .

# Get the output from the script.
# Some strange stuff to make sure we don't get an error
php output-list.php > /dev/null 2>&1

# FIXME Too lazy to think of a way to do this in one step...
if [ $? -gt 0 ]; then
        cd $OLDDIR
        exit 1
else
        php output-list.php | rev | cut -c 2- | rev
        cd $OLDDIR
        exit 0
fi

This is the (very simple) PHP script we use:

<?

require_once('wp-config.php');

$db = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);
if (!$db) {
        echo "Could not connect: " . mysql_error();
        die(1);
}

mysql_select_db(DB_NAME, $db);

$query = "select domain from wp_blogs";

$result = mysql_query($query);

if (!$result) {
        echo "Query failed: " . mysql_error();
        die(1);
}

$ret = "";

while ($row = mysql_fetch_assoc($result)) {
        $ret = $ret . $row['domain'] . ";";
}

echo $ret;

?>

This is the very small Fact I’ve written for it:

unless not FileTest.file?("/opt/wp-domain/getdomains.sh")
	Facter.add("wordpressdomains") do
        	setcode do
        	        %x{/opt/wp-domain/getdomains.sh}.chomp
        	end
	end
end

And last but not least, the puppet code:

class kbp-wordpressmu {
	file {
		"/opt/wp-domain":
			ensure => directory;
		"/opt/wp-domain/getdomains.sh":
			source => "puppet://puppet/kbp-wordpressmu/getdomains.sh",
			mode   => "755";
		"/opt/wp-domain/output-list.php":
			source => "puppet://puppet/kbp-wordpressmu/output-list.php";
	}

	$domains = split($wordpressdomains,";")

	if $domains != [] and $domains != "" {
		host { $domains:
			ip => $ipaddress,
		}
	}
}

Do let me know if you think this can be way cleaner!

Tags: convert, hack, hosts, puppet, puppet-tips-and-tricks, tricks, wordpress