VMoodle Block

VMoodle is a non standard infrastructure embedded within a Moodle block. It provides a technical toolset to deploy and manage a set of virtualized Moodles from a single codebase. All virtualized moodles will run their own instance independently from each other, or according themselves in building a Moodle Network cooperation strategy.

This work is the result of a couple of years of development with the participation of Intel Corp.

One of the key effect of using VMoodling virtualisation is that maintenance of multiple Moodle running with similar equipment gets much easier and saves a lot of time.

Moodle virtualisation process is achieved using a dynamic configuration definition, stored in a Moodle instance called "master instance". Virtualising such configuration allows dynamic switching of database and moodledata context when entering a Moodle page.

As was mentioned above, all the Moodle clones are completely independent and WILL NOT share any data. Using many instances with an adequate MNet strategy allows for the making of strong and powerful distributed Moodle configurations, aimed at large organizations.

Installation

Compatibility

VMoodle supports now MySQL databases and (less tested) PostgreSQL.

Note that VMoodle does not support PostGres schemas for node auto-deployement.

Prerequisites

The VMoodle blocks provides a complete and complex virtualisation process for Moodles and a set of network level administration capabilities. For the block running properly, compared to the original version in Moodle 1.9, Moodle 2 version of Moodle will need less core changes to operate in full feature range.

• Block bound XMLRPC calls. => natively resolved in Moodle 2.x new service registration method.
• Block sub-plugins => Now supported in the generic "subplugins" infrastructure.
• VMoodle based networks in a virtualisation configuration are intended to build coherent distributed platforms within an institutional environment. Urbanisation of such systems will often take some benefit of using extensively XMLRPC interactions between nodes for enhancing the distributed consistence. Standard Moodle codebase ensures MNet keys are renewed when a user jumps from a node to a remote node, but key ARE NOT renewed automatically when coming to obsolescence. The effect is that after a key has gone away, all services based on XMLRPC will be broken until key exchange has not been restored again. The VMoodle block provides an "automatic MNet key rotation" enhancement that fixes this situation. [1]. This point is not resolved in Moodle 2.0 architecture and still needs a patch in the MNet core library.

VMoodle distribution is provided with adequate patches for all these requirements.

IMPORTANT NOTE : On MySQL, VMoodle provides Moodle instance capturing for making deployment templates. This assumes the master Moodle controlling deployments needs having a MySQL user that has DATABASE CREATE permission.

Block Installation (quick install)

VMoodle block will install just as a usual Moodle block. Subplugins patch can be installed later, causing sub-plugins to be installed in a second stage :

1. Unzip the block code in the "blocks" folder of your Moodle install.
2. Trigger the administration/notification menu.

Once the block has been registered, there is a pair of things to do to get VMoodle start accepting virtualisation :

You need first to edit the copy the vconfig-dist.php in blocks/vmoodle to vconfig.php, and give the database access schema to your master database. (most often, this will use the same DB access credentials than master config.php). VConfig will look like :

  $CFG->vmasterdbhost = 'localhost';
  $CFG->vmasterdbtype = 'mysqli';
  $CFG->vmasterdbname = 'moodle';
  $CFG->vmasterdblogin = '<mydblogin>';
  $CFG->vmasterdbpass = '<mydbpass>';
  $CFG->vmasterdbpersist =  false;
  $CFG->vmasterprefix    = 'mdl_';
  $CFG->vmoodledefault    = 1; // tells if the default physical config can be used as true host

Keep this file in the blocks/vmoodle directory, or raise it up the the root level of Moodle. (No impact). What follows will consider the first option.

you need fist to hook the VMoodle configuration in your config file, and define explicitely the $CFG->dirroot key as this would be done too late by setup.php.

  $CFG->dirroot = '<your/moodle/path>';
  include_once $CFG->dirroot.'/blocks/vmoodle/vconfig.php';

Note that including from a hardwritten path will not preserve you to define $CFG->dirroot, as this path is used in VMoodle bootstrapping code.

VMoodle Block Features

Features Addressing the "Moodle Factory" Administration

• Virtualisation Hook for the standard 'config.php' Configuration file
• Deployment of new instances from within the Master instance administration
• Moodle snapshot to create platform templates for further deployment
• On demand Moodle deployment
• Deployment of virtualized Moodle within a Moodle Network strategy
• VMoodle Cron rotation handles automatically all instances in a VMoodle array.
• Additional Key Refresh Automation to keep SSH keys always consistent.

Features Addressing the "MNetwork Level Administration"

Multiplying instances will ever raise issues of administration because increasing the amount of information to be managed and complexity of the system. The VMoodle block provides a super-administration toolset allowing distributing administration commands across a Moodle Network so getting things faster even when the number of Moodle gets quite high. This administration layer provides a command framework for extensibility.

• SQL orders can be distributed on all managed nodes
• Role comparison and sync between many nodes
• Capability resync between many nodes
• Massive upgrade of all nodes when upgrading or installing new plugins.

Access to Mnetwork Level Administration

You may access to the MNet level administration clicking on the link "Administrate" showing in the footer of the "VMoodle" bloc instance.

Three subservices are available :

• Managing virtual instances and deployment : lists nodes and allows enabling, disabling snapshooting and deleting a node, ...
• Super-administration : a set of primitives that can be processed simultaneously on distributed Moodles.
• MNET Services Template : A form to define a template or MNet services settings to be applied as a default to any new Moodle clone.

See Also

VMoodle Virtualization block Modules and Plugins database entry.