Site Resilient MediaWiki Install - mysql

Question

I am trying to set up a MediaWiki site at work. I want it to be resilient across multiple sites, so what I am planning is 1 master database to take writes, and then a local slave database for each web install. This will mean I will have:
Server 1: MySQL Master
Server 2: MySQL Slave, Apache + MW
Server 3: MySQL Slave, Apache + MW
...
Server N: MySQL Slave, Apache + MW
What I want to happen, is if a site "goes dark", they will still have a local copy of the MW running in Read-Only mode, until it is able to contact the Master MySQL server again. I have set up the below configuration file on 1 of the slave hosts, which works fine. However, once I turn off the Master MySQL server to simulate a loss of connection, MW comes up with a DB error instead of just becoming Read-Only.
$wgDBservers = array(
array('host' => "10.10.10.10",
'dbname' => "db",
'user' => "####",
'password' => "####",
'type' => "mysql",
'flags' => DBO_DEFAULT,
'load' => 0),
array('host' => "localhost",
'dbname' => "db",
'user' => "####",
'password' => "####",
'type' => "mysql",
'flags' => DBO_DEFAULT,
'load' => 1)
);
Have I missed something from the configuration and this is something that I am able to do, or does it not work because it is not intended to work that way? Any help is appreciated.

Answer 1

This is not in any way "best practice" but in lieu of any other answer, I am posting it for anyone needing a quick work-around.
It is a PHP script that sits directly in the LocalSettings.php file and checks the status of the Master Database. The "proper" way to do it would probably be with an extension, but I don't have time to learn how to make one. You need to ensure that the user account that you are using to connect to MySQL, has Read-Only access to the slave database.
$wgDBSite_Master = array('host' => "<master ip>", 'dbname' => "<database>", 'user' => "<user>", 'password' => "<pass>", 'type' => "mysql", 'flags' => DBO_DEFAULT, 'load' => 0);
$Site_MasterTest = mysql_connect($wgDBSite_Master['host'], $wgDBSite_Master['user'], $wgDBSite_Master['password']);
if (!$Site_MasterTest) {
$wgReadOnly = 'Wiki failed to contact the Master server. Your site is currently running Dark. No edits will be saved.<br>Last Error: '.mysql_error();
$wgSiteNotice = $wgReadOnly;
$wgDBservers = array();
}
else {
$wgSiteNotice = 'Everything running normally, Captain';
$wgDBservers = array( $wgDBSite_Master );
}
$wgDBservers[] = array('host' => "localhost", 'dbname' => "<database>", 'user' => '<user>', 'password' => "<pass>", 'type' => "mysql", 'flags' => DBO_DEFAULT, 'load' => 1);