Tag Archives: howto

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I have previously written about using Git to add revision history to existing rsync backups. Having performed a number of configuration changes and system upgrades recently, I have found another use of Git which has proven invaluable.

It’s a fairly obvious hack, but it turns out that turning selected configuration directories (for example /etc/apache2/ and /etc/exim4/) into in situ Git repositories is a very handy thing to do.

The revision log you get in a Git repo gives you a very handy place to note down the reasons behind a certain configuration change. This provides a very handy historical context for a change, meaning you’re less likely to remove something odd that turns out later on to have been important.

Having configuration under version control also means that even if you do accidentally remove or change something that later causes problems you can easily roll them back.

Another handy feature is the ability to easily branch, so you can very quickly experiment with some wild configuration settings and very quickly revert them to the original working configuration should they turn out to be problematic or if you run out of time to complete them.

So, give it a try!

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In my earlier post I explained how to set up Elgg Multisite fresh, but as some of you have been asking, what if you already have an Elgg install and want to convert it to Elgg Multisite?

Well, providing your modifications have been mostly limited to plugins, this should be fairly straightforward. Unfortunately I don’t have time to answer all of you individually, but hopefully this post will help!

Getting started

Your first step should be to back up your existing Elgg install and back up the database, just in case anything goes wrong. If your current Elgg install is where you want to install your Elgg Multisite install (e.g. in /var/www) you will want to move it out of the way before continuing.

Once you’ve backed up and prepared your installation directory, set up Elgg Multisite as documented in my previous article.

Migrating your domain

Migrating your domain to point at your new Elgg multisite domain is a two step process, and you’ll need an extra sub domain depending on your configuration.

Basically, you’ll need one domain to act as an admin domain (e.g. pointing at /var/www), and then the domain your migrating should be pointed at the Elgg multisite docroot (e.g. in /var/www/docroot).

Next, you need to visit your admin domain and add the Elgg multisite domain details in the configuration – the domain name your migrating, plus the database details of the existing Elgg database you’re importing.

On the current version of Elgg Multisite you’ll get an error at this point complaining that the database could not be created. It already exists, so this error can be ignored.

Importing plugins

You should now have a functional vanilla Elgg install visible when you visit your migrated domain.

If you have any custom plugins which are not part of the standard Elgg install (including themes), these should be copied over at this point. You must activate them for the domain through the Elgg Multisite admin interface in order for them to be visible in Elgg’s plugin administration page.

Have fun!

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Elgg Multisite is a version of the popular social networking platform Elgg which lets you easily run multiple Elgg sites off a single install of the software, starting new Elgg sites at the click of a button.

Here’s how to get started…

What you’ll need

In addition to the existing Elgg system requirements (PHP 5.2+, Mysql, Apache) you will also need:

  • Control over your apache config: You will need to set up apache virtual hosts for each domain you want to run an Elgg site on and point it at your Elgg Multisite docroot. This is also true if you want to use wildcard subdomains (below).
  • A DNS provider that supports wildcard subdomains: Wildcard subdomains let you direct anything.yourdomain.com to a common endpoint, while preserving the request headers. This lets you serve up different content depending on whether you visit http://sitea.yourdomain.com vs http://siteb.yourdomain.com but without any extra configuration. This is the recommended Elgg Multisite setup.
  • A domain to act as the “Master”: Visiting this domain will bring up the Elgg Multisite control panel, so you’ll want to protect behind some form of access control. I recommend you modify your apache configuration to limit access to a handful of trusted IP addresses.

Installation

For this I am assuming you’ve got the domain example.com. You have your admin page at http://admin.example.com and your Elgg sites are at http://*.example.com.

  1. Download the source: Elgg Multisite is available on Github, either checkout the source and run the build.xml (you’ll need ant) or download the pre-built package for Elgg 1.7 or Elgg 1.8.
  2. Install the source to a suitable location: Unpack the Elgg Multisite and install the contents to a suitable location (e.g. /var/www/). You should end up with an index.php, plus the following sub directories…
    • schema: Holds the Elgg multisite admin database schema.
    • multi: Elgg multisite admin libraries.
    • docroot: The customised Elgg install where you will point your Elgg domains to.
    • data: Elgg multi’s data root, this will contain the data uploaded by your Elgg sites.
  3. Make the data directory writable: the previously mentioned data directory must be writable to the apache user (e.g chown www-root:www-root data; chmod 775 data; on most systems).
  4. Install the admin database schema: Install /var/www/schema/multisite_mysql.sql in a mysql database. Be sure to give the Elgg multisite admin user you configure in the next step the ability to create new databases!
  5. Rename /var/www/docroot/engine/settings.example.php to settings.php and configure the administration database settings:
    • $CONFIG->multisite->dbuser = 'your admin database user';
    • $CONFIG->multisite->dbpass = 'password';
    • $CONFIG->multisite->dbhost = 'host usually localhost';
    • $CONFIG->multisite->dbname = 'admin database name e.g. elggmultisite';

Configuring your domains

The next step is to set up your Apache virtual hosts to point to the appropriate locations in your Elgg Multisite install.

  1. Set up your admin domain: Point a domain at your admin root /var/www/, e.g

    <VirtualHost *>
    ServerAdmin webmaster@example.com
    ServerName admin.example.com
    DirectoryIndex index.html index.php
    DocumentRoot /var/www/
    UseCanonicalName off
    php_admin_flag engine on
    php_admin_flag safe_mode off
    <Directory "/var/www/">
    AllowOverride All
    Options +Indexes +Includes +FollowSymlinks +ExecCGI
    </Directory>
    </VirtualHost>

  2. Set up your Elgg Multi-site wildcard domain handler:

    <VirtualHost *>
    ServerAdmin webmaster@example.com
    ServerName hosts.example.com
    ServerAlias *.example.com
    DirectoryIndex index.html index.php
    DocumentRoot /var/www/docroot/
    UseCanonicalName off
    php_admin_flag engine on
    php_admin_flag safe_mode off
    <Directory "/var/www/docroot/">
    AllowOverride All
    Options +Indexes +Includes +FollowSymlinks +ExecCGI
    </Directory>
    </VirtualHost>

  3. Set up the appropriate hosts and wildcard domains with your DNS provider: You need to set up your DNS correctly for this configuration to work, and this is host specific. Your DNS provider can help you further.

Setting up your admin user and adding sites

Once you have set up everything, visit http://admin.example.com and you will be prompted to enter details for the administrator user.

You can then begin setting up and configuring individual Elgg sites!

Enjoy!