Propeller-heads Unite!

When I first started working with Moodle servers, one of the things that bugged me was the fact that it required a complete install of the code for every site hosted on the system. While that’s fine for most circumstances, it really did not work well in our environment where we’re looking at potentially hosting hundreds of Moodle instances. So, in the fine open source tradition of scratching an itch by finding something someone else has done, modifying it, and then sharing it with the world … I give you shared-code Moodle, OSL-style.

First, though, credit where credit is due. Martin Langhoff posted almost all of what we needed to do here. All I needed to do is expand upon it to fit our needs.

Second, what the modified code actually does:
1) config.php looks in Moodle dirroot/multisite_config for an ini file matching the server name. I.E.: fqdn.domain.org.ini
2) If found, the ini file is parsed and used to populate the Moodle $CFG

On to the code!

1) Create a directory in your Moodle wwwroot named multisite_config and make sure it’s readable by the web server
2) Create a moodledata_shared directory to hold the various sites’ moodledata directories
3) Modify the wwwroot/config.php file to look like:
<?php /// Moodle Configuration File
unset($CFG);
$CFG->dirroot = '/var/www/moodle_shared';
// Determine hostname
$hostname = $_SERVER['HTTP_HOST'];
if (isset($_ENV['HTTP_HOST'])){ // this is to support cronjobs on a per-host basis
$hostname = $_ENV['HTTP_HOST'];
}
// Load multi-site configs
$multisite_config_filename = "$CFG->dirroot/multisite_config/$hostname.ini";
if (file_exists($multisite_config_filename)) {
$sites_array = parse_ini_file($multisite_config_filename);
} else {
// Whoops! No ini found, fall back to a default Moodle host
$URL="http://default-moodle.domain.org";
header ("Location: $URL");
die("<pre>Unable to open site configuration file for '$hostname'. Has the config file been created?\n</pre>");
}
$CFG->dbtype = 'mysql';
$CFG->dbhost = $sites_array[dbhost];
$CFG->dbname = $sites_array[dbname];
$CFG->dbuser = $sites_array[dbuser];
$CFG->dbpass = $sites_array[dbpass];
$CFG->dbpersist = false;
$CFG->prefix = 'mdl_';
$CFG->wwwroot = $sites_array[wwwroot];
$CFG->dataroot = '/var/www/moodledata_shared/'.$hostname;
$CFG->admin = 'admin';

4) Create an ini file for each Moodle instance you want to host and place it in the Moodle dirroot/multisite_config/ directory. An example ini file for a fictitious template.domain.org Moodle instance:
; multisite_config.ini
[template]
dbhost = localhost
dbname = template_db_name
dbuser = template_user
dbpass = dbpassword
wwwroot = http://template.domain.org/moodle

5) Create a moodledata_shared/hostname directory for the moodledata stuff.

I have a canned mysqldump file I use to create new Moodle sites instead of using the GUI (along with an automated system to create the databases and generate the ini files, but that’s a topic for another post another time). Since I wanted to avoid creating a vhost for every Moodle instance and having to bounce Apache every time I add a new one, I set up a wildcard domain to point at the moodle_shared webroot. But this should work equally well with explicitly-defined Apache vhosts.

Todo:
1) Modify the GUI config to have it write the ini files directly.
2) Look into having site-specific modules. As it stands right now, all sites get the same modules. So far we haven’t run into module conflicts or sites wanting customized versions of modules, but I expect it’s only a matter of time.
3) Performance and scaling testing. This seems to work well enough with the approximately 50 low traffic sites I’m running now, but I’m not sure how much of a penalty the reading and parsing of the ini file imposes. It may not scale well on high traffic sites.
3a) Not sure how well this might be adapted to a multi-server or clustered environment.

2 Comments »

Thanks to krimsly for passing this little tidbit along: http://mfeldstein.com/index.php/weblog/permalink/blackboard_patents_the_lms

Err … wot? Almost every system I’ve built or run for the past decade probably violates that patent. I was running distance ed courses on a FirstClass server for the State of Oregon in 1994. Prior to that, we had been running a text menu-based system on EIES2 for several years before migrating to FirstClass. I think I saw a post somewhere once about a mainframe/terminal distance ed system back in the late 60’s. Their claim, filed in 1999, is (if you’ll pardon the pun) patently ridiculous. In an interview with the Chronicle of Higher Education, Matthew Small, senior vice president and general counsel for Blackboard stated:

He [Small] said many e-learning companies could operate without infringing on the patent, though he declined to provide any examples. However, he also said that had Blackboard not merged with WebCT, then WebCT would have been infringing the patent.

I am certainly not a lawyer, but couldn’t WebCT itself be considered “prior art”? The WebCT product was developed in 1995-1996 and the WebCT corporation was spun off from the University of British Columbia in 1997. Mr. Small’s own quote identifies a product that existed commercially two years before they filed for the patent.

Apparently the lawsuits started before the ink was even dry on the USPTO documents: http://www.theinquirer.net/images/articles/blackboard.pdf

Demanding a jury trial in rural east Texas for a software technology patent infringement lawsuit? Come on, now.

6 Comments »