Create a Wikifarm - Revision history

Saruman!: /* General procedure to creat a wikifarm wiki instance */ updated external link

2011-08-11T04:27:47Z

General procedure to creat a wikifarm wiki instance: updated external link

← Older revision		Revision as of 06:27, 11 August 2011
Line 18:		Line 18:
	* Set up your second wiki as if it were the first one, and move it over to the wiki farm.		* Set up your second wiki as if it were the first one, and move it over to the wiki farm.
	* et cetera.		* et cetera.
	Because of the manual work involved, this system is not very well suited to "big" wikifarms; for those instances you'd be better off with one of the scripts that creates the wikifarm instance, and populates it with a default database and default configuration file. Scripts and instructions can be found on the Internet, like this one [http://www.jirp.nl/2008/04/11/mediawiki-farm-multiple-wiki/ on jirp.nl].<br>		Because of the manual work involved, this system is not very well suited to "big" wikifarms; for those instances you'd be better off with one of the scripts that creates the wikifarm instance, and populates it with a default database and default configuration file. Scripts and instructions can be found on the Internet, like this one [http://www.jirp.nl/2008/07/27/mediawiki-farm-administer-multiple-wiki-environments/ on jirp.nl].<br>
	However, the method is quite doable when you've only got a handful of wikis to create, and remains largely compatible with Debians mechanisms for updating packages.		However, the method is quite doable when you've only got a handful of wikis to create, and remains largely compatible with Debians mechanisms for updating packages.

Saruman!: Extensions section started

2009-03-05T18:52:35Z

Extensions section started

← Older revision		Revision as of 20:52, 5 March 2009
Line 182:		Line 182:
	</VirtualHost>		</VirtualHost>
	Now restart Apache2, and visit the link designated to the new wiki, in this case ''<nowiki>http://www.iceditch.nl/mediawiki</nowiki>''. You'll get the familiar "please set up the wiki first" message. Click it, and manually configure your new wiki. When you're done, move the created ''LocalSettings.php'' to ''/etc/mediawiki'' and you're set! Your new wiki is running in the default position, and as soon as you've moved it to the wikifarm, you can create yet another wiki!		Now restart Apache2, and visit the link designated to the new wiki, in this case ''<nowiki>http://www.iceditch.nl/mediawiki</nowiki>''. You'll get the familiar "please set up the wiki first" message. Click it, and manually configure your new wiki. When you're done, move the created ''LocalSettings.php'' to ''/etc/mediawiki'' and you're set! Your new wiki is running in the default position, and as soon as you've moved it to the wikifarm, you can create yet another wiki!

			==Debian extensions and your wiki farm==
			So how about those interesting MediaWiki extensions? Well, if you've [[Mediawiki-extensions_under_Debian\|installed package ''mediawiki-extensions'']] then you've got a default structure for handling extensions, that's slightly more intelligent than the standard MediaWiki way, ''and'' helps us a long way towards different extension configurations for our wikis in the farm.

			In advance we offer you the following information: after installation of ''mediawiki-extensions'', the Debian version of MediaWiki allows you to enable and disable extensions by simply running the command ''mwenext <extension>'' or ''mwdisext <extension>'', e.g.
			mwenext ConfirmEdit.php
			It does this by having a directory with symlinks to all availabe extensions, and another directory where you can symlink those extensions that you want enabled. Now this mechanism can be extended to the wikifarm in two different ways:
			# Per wiki a different selection of all installed extensions is made available. Per wiki in the farm, a selection of those extensions ''that are available to THAT wiki instance'' can be enabled.
			# All extensions that are installed are available to all wikis in the wikifarm, but for each wiki a different selection can be enabled.
			We will not describe the first case, but rather the second one.

Saruman!: /* Debian Mediawiki wikifarm structure */ added wiki user note

2009-03-04T21:19:24Z

Debian Mediawiki wikifarm structure: added wiki user note

Saruman!: /* Adding more MediaWiki instances to your farm */ done

2009-03-04T21:05:56Z

Adding more MediaWiki instances to your farm: done

← Older revision		Revision as of 23:05, 4 March 2009
Line 178:		Line 178:

	</VirtualHost>		</VirtualHost>
	Now restart Apache2, and visit the link designated to the new wiki, in this case ''<nowiki>http://www.iceditch.nl/mediawiki</nowiki>''. You'll get the familiar "please set up the wiki first" message. Click it, and manually configure your new wiki.		Now restart Apache2, and visit the link designated to the new wiki, in this case ''<nowiki>http://www.iceditch.nl/mediawiki</nowiki>''. You'll get the familiar "please set up the wiki first" message. Click it, and manually configure your new wiki. When you're done, move the created ''LocalSettings.php'' to ''/etc/mediawiki'' and you're set! Your new wiki is running in the default position, and as soon as you've moved it to the wikifarm, you can create yet another wiki!

Saruman!: /* Adding more MediaWiki instances to your farm */ first description

2009-03-04T20:52:06Z

Adding more MediaWiki instances to your farm: first description

← Older revision		Revision as of 22:52, 4 March 2009
Line 131:		Line 131:

	==Adding more MediaWiki instances to your farm==		==Adding more MediaWiki instances to your farm==
			So how do you now prepare the next wiki in your farm? Quite simple. We're now going to set up the next wiki in the default place, being ''/var/lib/mediawiki'', after which we can return to the previous step of [[Create_a_Wikifarm#Linking_to_the_shared_code_base\|creating another copy of the code base]] and again move the new wiki over from the default location to its location in our fresh wiki farm.

			So we need to set up the next website with access to the (now empty) default wiki location. We say "now empty" because the default location is lacking a ''LocalSettings.php'' file. In essence then, it is again an empty wiki, for which we'll have to run through the steps of basic configuration, as described in [[Basic_MediaWiki_Installation\|basic MediaWiki installation]].

			First off, we'll link the next virtual website to the default wiki location. Suppose the next virtual website is called "iceditch.nl", and our wiki database will be called IceditchWiki. We'll start off by creating a location for the IceditchWiki configuration files under the MediaWiki configuration directory:
			cd /etc/mediawiki
			mkdir iceditch.nl
			cp apache.conf iceditch.nl/apache.conf
			Next, we'll instruct our virtual host to load this new MediaWiki apache configuration file:
			cd /etc/apache2/sites-available
			vi 010-iceditch.nl
			Inside of this virtual host file, we include the MediaWiki configuration; the virtual host file then looks something like this:
			<VirtualHost *:80>
			ServerName www.iceditch.nl
			ServerAdmin webmaster@iceditch.nl

			DocumentRoot /var/www/iceditch.nl
			<Directory />
			Options FollowSymLinks
			AllowOverride None
			</Directory>
			<Directory /var/www/iceditch.nl>
			Options Indexes FollowSymLinks MultiViews
			AllowOverride None
			Order allow,deny
			allow from all
			</Directory>

			Include /etc/mediawiki/iceditch.nl/apache.conf

			ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
			<Directory "/usr/lib/cgi-bin">
			AllowOverride None
			Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
			Order allow,deny
			Allow from all
			</Directory>

			ErrorLog /var/appslog/apache2/iceditch.nl-error.log

			# Possible values include: debug, info, notice, warn, error, crit,
			# alert, emerg.
			LogLevel notice

			CustomLog /var/appslog/apache2/iceditch.nl-access.log combined

			</VirtualHost>
			Now restart Apache2, and visit the link designated to the new wiki, in this case ''<nowiki>http://www.iceditch.nl/mediawiki</nowiki>''. You'll get the familiar "please set up the wiki first" message. Click it, and manually configure your new wiki.

Saruman!: finished moving over

2009-03-04T12:37:28Z

finished moving over

← Older revision		Revision as of 14:37, 4 March 2009
Line 57:		Line 57:

	==Linking to the shared code base==		==Linking to the shared code base==
	Now we can create links to the code base for each wikifarm instance. You need to create symlinks in your chosen wiki directory (e.g. ''/opt/mediawikifarm/saruman.biz'') to all files and folders in ''/~~var~~/~~lib~~/mediawiki'', except the directory ''images'' and the files ''AdminSettings.php'' (if it even exists) and ''LocalSettings.php''. Such a thing can be done simplest with a little script like this:		As you can see from the [[MediaWiki directory structure]], the code that is actually served in the webserver is in two separate trees: by default the webserver ''thinks'' the full tree is in ''/var/lib/mediawiki'', but a large part of what you find in that spot is actually symlinked to files and directories in ''/usr/share/mediawiki''. Actually, the tree ''/usr/share/mediawiki'' can be thought of as a source code library, and ''/var/lib/mediawiki'' as the instance that we're actually serving. Since an instance needs both source code and some files of its own, we find that ''/var/lib/mediawiki'' contains both links to that source code, as well as actual files and directories.

			Now we can create links to the code base for each wikifarm instance for themselves. You need to create symlinks in your chosen wiki directory (e.g. ''/opt/mediawikifarm/saruman.biz'') to all files and folders in ''/usr/share/mediawiki'', except the directory ''images'' and the files ''AdminSettings.php'' (if it even exists) and ''LocalSettings.php''. Such a thing can be done simplest with a little script like this:
	<source lang="bash">		<source lang="bash">
	WSRC='/~~var~~/~~lib~~/mediawiki'		WSRC='/usr/share/mediawiki'
	WDEST='/opt/mediawikifarm/saruman.biz'		WDEST='/opt/mediawikifarm/saruman.biz'
	cd $WSRC		cd $WSRC
Line 94:		Line 96:

	===Move the Wiki website===		===Move the Wiki website===
	~~As you can see from the [[MediaWiki directory structure]]~~, the ~~code~~ that ~~is actually~~ served in the ~~webserver is in two separate trees: by default~~ the ~~webserver~~ ''~~thinks~~'' the ~~full tree is in~~ ''/~~var~~/~~lib~~/~~mediawiki~~''~~, but a large part~~ of ~~what you find in that spot is actually symlinked~~ to ~~files and~~ directories ~~in ''~~/~~usr~~/~~share~~/~~mediawiki''~~. ~~Actually, the tree ''~~/~~usr~~/~~share~~/~~mediawiki'' can be thought of as a source code library, and ''~~/~~var~~/~~lib~~/~~mediawiki'~~' as the ~~instance~~ that we'~~re actually serving. Since an instance needs both source code and some files of its own, we find that~~ ''~~/var/lib/mediawiki~~'' ~~contains both links to~~ that ~~source code~~, ~~as well as actual files and directories~~.		So what we now need to do, is to tell the webserver that the full tree can be served from the codebase we prepared. To this end, we need to change the apache2 configuration file ''apache.conf'' of the Wiki, that we've previously copied over to the Mediawiki configuration directory ''/etc/mediawiki/SaruWiki'' and that's included in the Virtual Host file of the saruman.biz website. This file needs to point to the new shared code location; it will look something like this:
			Alias /wiki /opt/mediawikifarm/saruman.biz

			<Directory /opt/mediawikifarm/saruman.biz/>
			Options +FollowSymLinks
			AllowOverride All
			order allow,deny
			allow from all
			</Directory>

			# some directories must be protected
			<Directory /opt/mediawikifarm/saruman.biz/config>
			Options -FollowSymLinks
			AllowOverride None
			</Directory>
			<Directory /opt/mediawikifarm/saruman.biz/upload>
			Options -FollowSymLinks
			AllowOverride None
			</Directory>
			Note that we haven't created the upload directory (but we can if we ever need it). Also note that we haven't created the ''config'' directory; that is because we don't need that in this wikifarm instance, because this particular instance has already been configured.

	~~So what~~ we now need to ~~do, is to tell the webserver that the full tree~~ can ~~be served from elsewhere, and in that spot "elsewhere" create symlinks to~~ the ~~right spots~~. ~~Let~~'~~s begin with~~ the ~~latter.~~		Furthermore, we now need to make sure Apache2 can find the (working) ''LocalSettings.php'' from the new wiki location ''/opt/mediawikifarm/saruman.biz'', '''AND''' we need to change a setting within ''LocalSettings.php'' to reflect the new wiki location. For the first bit, we make the correct link(s):
			cd /opt/mediawikifarm/saruman.biz
	~~Let's assume we wish to move our default Wiki instance to~~ ''/~~data~~/~~wikifarm~~/~~SaruWiki''~~. ~~Other instances could then run under~~ ''~~/data/wikifarm/<instancename>~~''~~. We now first create the links to the~~ ''~~/usr/share/mediawiki~~'' ~~files as~~ we ~~see them in the~~ ''~~/var/lib/mediawiki~~'' ~~instance~~:		ln -s /etc/mediawiki/SaruWiki/AdminSettings.php
	cd /~~data~~/~~wikifarm~~/~~SaruWiki~~		ln -s /etc/mediawiki/SaruWiki/LocalSettings.php
	for i in /usr/share/mediawiki/*.~~php; do~~		(even if you don't have the ''AdminSettings.php'' file yet, you can still make that link).
	~~> ln -s $i~~		For the second bit, we edit
	~~> done~~		# We define this to allow the configuration file to be explicitly
	~~unlink AdminSettings.php~~		# located in /etc/mediawiki.
	~~unlink LocalSettings.php~~		# Change this if you are setting up multisite wikis on your server.
	ln -s /~~usr/share~~/mediawiki/*.phtml		define('MW_INSTALL_PATH','/opt/mediawikifarm/saruman.biz');
	~~ln -s~~ /~~usr/share/mediawiki/install-utils~~.~~inc~~		This should be enough! Restart Apache2 and test the result
	ln -s /~~usr/share~~/mediawiki/~~includes~~		invoke-rc.d apache2 restart
	~~ln -s~~ /~~usr/share/mediawiki/languages~~
	~~ln -s /usr/share/mediawiki/maintenance~~
	~~ln -s /usr/share/mediawiki/skins~~
	~~Next, we create the directories that contain the instance-specific files, i.e. the files that belong to this one member of the Wiki farm. This includes~~ the ''~~images~~'' ~~directory~~, ~~where users of this wiki instance~~ can ~~upload their images~~.
	~~mkdir images~~
	~~chown www-data:www-data images~~
	~~mkdir config~~
	~~chown www-data:www-data config~~
	~~cp -P~~ /~~var~~/~~lib~~/mediawiki/config/* .

	==Adding MediaWiki instances to your farm==		==Adding more MediaWiki instances to your farm==

Saruman!: /* Move the Wiki configuration within /etc */ note about codebase

2009-03-04T11:34:32Z

Move the Wiki configuration within /etc: note about codebase

← Older revision		Revision as of 13:34, 4 March 2009
Line 91:		Line 91:
	unlink AdminSettings.php		unlink AdminSettings.php
	ln -s /etc/mediawiki/SaruWiki/AdminSettings.php		ln -s /etc/mediawiki/SaruWiki/AdminSettings.php
	If you now restart Apache2, your Wiki will still work - but the two primary configuration files have moved over to a dedicated spot.		If you now restart Apache2, your Wiki will still work - but the two primary configuration files have moved over to a dedicated spot. Also note that you're not yet using the new codebase - that comes later.

	===Move the Wiki website===		===Move the Wiki website===

Saruman!: shared codebase linking added

2009-03-04T11:02:33Z

shared codebase linking added

@@ Line 57: / Line 57: @@
 ==Linking to the shared code base==
-Now we can create links to the code base for each wikifarm instance.
+Now we can create links to the code base for each wikifarm instance. You need to create symlinks in your chosen wiki directory (e.g. ''/opt/mediawikifarm/saruman.biz'') to all files and folders in ''/var/lib/mediawiki'', except the directory ''images'' and the files ''AdminSettings.php'' (if it even exists) and ''LocalSettings.php''. Such a thing can be done simplest with a little script like this:
 ==Recreating (moving over) your first MediaWiki instance==

Saruman!: laid in the wikifarm procedure

2009-03-04T08:49:34Z

laid in the wikifarm procedure

← Older revision		Revision as of 10:49, 4 March 2009
Line 8:		Line 8:
	* Multiple wikis, running on '''a shared code base, and on a shared database'''. This could be a good solution for multiple wikis for a single website, because a user can register on one wiki, and automatically have the same account in the other database as well.		* Multiple wikis, running on '''a shared code base, and on a shared database'''. This could be a good solution for multiple wikis for a single website, because a user can register on one wiki, and automatically have the same account in the other database as well.
	We're not going to go into the first type, since the shared codebase is more maintainable. Instead, we're going to show how you can share the Mediawiki code base under Debian, so that a Debian update to the Mediawiki package is automatically applied to all instances of your wikifarm. And we'll see that from there, the choice between separate databases or shared databases is quite trivial.		We're not going to go into the first type, since the shared codebase is more maintainable. Instead, we're going to show how you can share the Mediawiki code base under Debian, so that a Debian update to the Mediawiki package is automatically applied to all instances of your wikifarm. And we'll see that from there, the choice between separate databases or shared databases is quite trivial.
			===Wikifarming under Debian===
			As with most Linux-based software packages, the MediaWiki package ''mediawiki'' that Debian offers is modified to suit the Debian policies and needs. This means that it has moved all configuration files to reside under ''/etc/mediawiki'', but also that it offers a somewhat better way to include extensions. The downside of these modifications is that creating a wikifarm under Debian is somewhat more complicated than when you're using vanilla MediaWiki sources - mostly because there isn't much documentation on the Internet about it. In the following we'll be documenting one possible way to create a wikifarm. Note that our method is particularly well-suited to "small" wikifarms (a handful of wikis on a single server), and not exactly fit for "big" wikifarms (thousands of wikis on one or more servers).

			==General procedure to creat a wikifarm wiki instance==
			Setting up a wiki under Debian is quite easy - as you might have seen from this wiki's description under entry [[Basic MediaWiki Installation]]. This is because the Debian customization includes specific changes to some MediaWiki files, and to the default configuration files. Thus, the usual methods of creating a wiki instance next to the default one run into an additional obstacle: the forementioned Debian customizations. The way around it is this:
			* We suppose you've already installed your first wiki. It'll probably be just as described in the [[Basic MediaWiki Installation]].
			* Make sure you adapt this first wiki to support virtual hosts, as described in the section on [[Place_MediaWiki_inside_a_Virtual_Host\|placing MediaWiki inside a Virtual Host]].
			* If your first wiki is running OK, follow the instructions in the next set of sections to move the wiki from its default place to the wikifarm. As a result, your first wiki should still run OK, but the place where Debian expects your wiki to live is now "empty" again
			* Set up your second wiki as if it were the first one, and move it over to the wiki farm.
			* et cetera.
			Because of the manual work involved, this system is not very well suited to "big" wikifarms; for those instances you'd be better off with one of the scripts that creates the wikifarm instance, and populates it with a default database and default configuration file. Scripts and instructions can be found on the Internet, like this one [http://www.jirp.nl/2008/04/11/mediawiki-farm-multiple-wiki/ on jirp.nl].<br>
			However, the method is quite doable when you've only got a handful of wikis to create, and remains largely compatible with Debians mechanisms for updating packages.

	==Debian Mediawiki wikifarm structure==		==Debian Mediawiki wikifarm structure==
Line 16:		Line 28:
	* ''/usr/share/mediawiki'' contains the source code. It is not used directly, rather it is linked to from the ''/var/lib/mediawiki'' directory.		* ''/usr/share/mediawiki'' contains the source code. It is not used directly, rather it is linked to from the ''/var/lib/mediawiki'' directory.
	* ''/var/lib/mediawiki'' contains the site, including links to the configuration files in ''/etc/mediawiki''.		* ''/var/lib/mediawiki'' contains the site, including links to the configuration files in ''/etc/mediawiki''.
	Within these branches, we should not delete or move any file or directory, since that will confuse our [[APT\|Debian package manager]] when an update to the ''mediawiki'' package becomes available, so we strive to minimize the changes to this structure.		Within these branches, we should not delete or move any file or directory, since that will confuse our [[APT\|Debian package manager]] when an update to the ''mediawiki'' package becomes available, so we strive to minimize the changes to this structure. Furthermore, the default configuration files explicitly declare the wiki to "live" in ''/var/lib/mediawiki'', so we'll designate the wiki in that location as the "default wiki" as opposed by "wikifarm instances" that live e.g. under ''/var/wikifarm/<instancename>''.
	===Extending the structure for a wikifarm===		===Extending the structure for a wikifarm===
	First we need a label, a name for each wikifarm, so that we can label ~~the wiki instances~~ we're creating. Each name needs to be unique because we're going to create directories based on the labels. Note that this label need ~~NOT~~ be the Wiki name, as you fill it in when [[Basic_MediaWiki_Installation#Configuring_the_Wiki_instance\|configuring the wiki instance]]. In our example, we use the domain name of the website on which the wiki instance is running.		First we need a label <instancename>, which designates the name for each wikifarm instance, so that we can label them as we're creating them. Each name needs to be unique because we're going to create directories based on the labels. Note that this label need not be the Wiki name, as you fill it in when [[Basic_MediaWiki_Installation#Configuring_the_Wiki_instance\|configuring the default wiki instance]], although you could of course use that name. In our example, we use the domain name of the website on which the wiki instance is running. Thus, this wiki named "SaruWiki" is instance "saruman.biz" in our little wikifarm.

	Furthermore, you need a database name for each wiki instance that gets its own database. You could use the label you've chosen, or different ones, or derived ones. Remember to observe the MySQL [http://dev.mysql.com/doc/refman/5.0/en/identifiers.html limits on database names] (no more than 64 characters, no slashes or dots in the name, not ending in a space et cetera).		Furthermore, you need a database name for each wiki instance that gets its own database, and it should be different from the default database name "wikidb" (unless you ''want'' to put your wiki instance into this default database, together with the wiki or wikis that are already in there). You could use the label you've chosen, or different ones, or derived ones. Remember to observe the MySQL [http://dev.mysql.com/doc/refman/5.0/en/identifiers.html limits on database names] (no more than 64 characters, no slashes or dots in the name, not ending in a space et cetera).

	Thus, you could have labels and database names like this:		Thus, you could have labels and database names like this:
Line 27:		Line 39:
	* ann.example.org and wiki-ann		* ann.example.org and wiki-ann
	* bob.example.org and wiki-bob		* bob.example.org and wiki-bob
	* charles.example.org ~~wiki-charles~~		* charles.example.org and wikiCharles
	And remember, they are just labels. You could just as easily use user names, numbers or whatever. For maintainability though, we recommend recognizable labels. On the other hand, there are a number of labels you must avoid, because they will come to conflict with directories that already exist: most notably ''config'', ''extensions'' and ''images''. So before you begin, sit down and write out what your label and database name convention will be. This is trivial if you have just a handful of wikis, but can become very important ~~when~~ you~~'ve got~~ hundreds of instances.		And remember, they are just labels. You could just as easily use user names, numbers or whatever. For maintainability though, we recommend a consistent scheme with recognizable labels. On the other hand, there are a number of labels you must avoid, because they will come to conflict with directories that already exist: most notably ''config'', ''extensions'' and ''images''. So before you begin, sit down and write out what your label and database name convention will be. This is trivial if you have just a handful of wikis, but can become very important should you ever grow to hundreds of instances.

	Each wikifarm will need its own set of configuration files, so for each new wiki instance we'll create directories under ''/etc/mediawiki'' using the chosen wiki labels:		Each wikifarm will need its own set of configuration files, so for each new wiki instance we'll create directories under ''/etc/mediawiki'' using the chosen wiki labels:

Saruman!: /* Extending the structure for a wikifarm */ added images dir

2009-03-02T17:40:57Z

Extending the structure for a wikifarm: added images dir

← Older revision		Revision as of 19:40, 2 March 2009
Line 36:		Line 36:
	Make each of these directories owned by the Apache2 user (''chmod www-data:www-data saruman.biz'' et cetera).		Make each of these directories owned by the Apache2 user (''chmod www-data:www-data saruman.biz'' et cetera).

	Each wikifarm will need its own code base, so for each new wiki instance we'll create directories under ''/~~var~~/~~lib/mediawiki~~'' using the wiki labels:		Each wikifarm will need its own code base, so for each new wiki instance we'll create directories under ''/opt/mediawikifarm'' using the wiki labels:
	* ''/~~var~~/~~lib/mediawiki~~/saruman.biz''		* ''/opt/mediawikifarm/saruman.biz''
	* ''/~~var/lib~~/~~mediawiki~~/iceditch.nl''		* ''/opt/mediawikifarm/iceditch.nl''
	* et cetera.		* et cetera.
			The choice for ''/opt/mediawikifarm'' is quite arbitrary; one could make a case to use ''/var/www'' or ''/var/lib/mediawikifarm/'' or anything like this, but ''/opt'' is meant for optional software, which under Debian is software that's not in the standard repositories. And since the wikifarm isn't, it makes sense to create the links to the codebase there.

			Each wikifarm may have its own upload directory for images. This directory should not be placed under ''/opt'', but rather in a place where you expect data, e.g. ''/data'' if you have that, or ''/var/www'', or something like this. We have chosen for ''/data/wikifarm/<wikilabel>/images''.

	==Linking to the shared code base==		==Linking to the shared code base==

← Older revision		Revision as of 23:19, 4 March 2009
Line 28:		Line 28:
	* ''/usr/share/mediawiki'' contains the source code. It is not used directly, rather it is linked to from the ''/var/lib/mediawiki'' directory.		* ''/usr/share/mediawiki'' contains the source code. It is not used directly, rather it is linked to from the ''/var/lib/mediawiki'' directory.
	* ''/var/lib/mediawiki'' contains the site, including links to the configuration files in ''/etc/mediawiki''.		* ''/var/lib/mediawiki'' contains the site, including links to the configuration files in ''/etc/mediawiki''.
	Within these branches, we should not delete or move any file or directory, since that will confuse our [[APT\|Debian package manager]] when an update to the ''mediawiki'' package becomes available, so we strive to minimize the changes to this structure. Furthermore, the default configuration files explicitly declare the wiki to "live" in ''/var/lib/mediawiki'', so we'll designate the wiki in that location as the "default wiki" as opposed by "wikifarm instances" that live e.g. under ''/var/wikifarm/<instancename>''.		Within these branches, we should not delete or move any file or directory, since that will confuse our [[APT and aptitude\|Debian package manager]] when an update to the ''mediawiki'' package becomes available, so we strive to minimize the changes to this structure. Furthermore, the default configuration files explicitly declare the wiki to "live" in ''/var/lib/mediawiki'', so we'll designate the wiki in that location as the "default wiki" as opposed by "wikifarm instances" that live e.g. under ''/var/wikifarm/<instancename>''.<br>
			Another important element of the MediaWiki structure is hidden in its use of the MySQL database: during setup, you either need to have a database user account, or a MySQL superuser account (e.g. 'root'@'localhost') so as to be able to create the wiki database and a database user account.

	===Extending the structure for a wikifarm===		===Extending the structure for a wikifarm===
	First we need a label <instancename>, which designates the name for each wikifarm instance, so that we can label them as we're creating them. Each name needs to be unique because we're going to create directories based on the labels. Note that this label need not be the Wiki name, as you fill it in when [[Basic_MediaWiki_Installation#Configuring_the_Wiki_instance\|configuring the default wiki instance]], although you could of course use that name. In our example, we use the domain name of the website on which the wiki instance is running. Thus, this wiki named "SaruWiki" is instance "saruman.biz" in our little wikifarm.		First we need a label <instancename>, which designates the name for each wikifarm instance, so that we can label them as we're creating them. Each name needs to be unique because we're going to create directories based on the labels. Note that this label need not be the Wiki name, as you fill it in when [[Basic_MediaWiki_Installation#Configuring_the_Wiki_instance\|configuring the default wiki instance]], although you could of course use that name. In our example, we use the domain name of the website on which the wiki instance is running. Thus, this wiki named "SaruWiki" is instance "saruman.biz" in our little wikifarm.

	Furthermore, you need a database name for each wiki instance that gets its own database, and it should be different from the default database name "wikidb" (unless you ''want'' to put your wiki instance into this default database, together with the wiki or wikis that are already in there). You could use the label you've chosen, or different ones, or derived ones. Remember to observe the MySQL [http://dev.mysql.com/doc/refman/5.0/en/identifiers.html limits on database names] (no more than 64 characters, no slashes or dots in the name, not ending in a space et cetera).		Furthermore, you need a database name for each wiki instance that gets its own database, and it should be different from the default database name "wikidb" (unless you ''want'' to put your wiki instance into this default database, together with the wiki or wikis that are already in there). You could use the label you've chosen, or different ones, or derived ones. Remember to observe the MySQL [http://dev.mysql.com/doc/refman/5.0/en/identifiers.html limits on database names] (no more than 64 characters, no slashes or dots in the name, not ending in a space et cetera).<br>
			In addition, you need a database user name and password. This should not be the same user name and password that you've used to set up any other wiki database, or you'd have a security risk. In the unfortunate case in which you'd feel compelled to reuse a database user name (e.g. the standard "wikiuser"), be sure to reuse the original password of "wikiuser", or risk losing access to the earlier wikis that use that same user.

	Thus, you could have labels and database ~~names~~ like this:		Thus, you could have labels, database names and database username/passwords like this:
	* saruman.biz and saruman-biz-wiki		* saruman.biz and saruman-biz-wiki and saruwikiuser/Gp5Zmull01
	* iceditch.nl and iceditchNLwiki		* iceditch.nl and iceditchNLwiki and icewikiuser/Br3thReeka1
	* ann.example.org and wiki-ann		* ann.example.org and wiki-ann and ann/Tr4p7qqhl2
	* bob.example.org and wiki-bob		* bob.example.org and wiki-bob and bobwiki/Gnff3Prkks
	* charles.example.org and wikiCharles		* charles.example.org and wikiCharles and charles/Pzmel55Fgzxm
	And remember, they are just labels. You could just as easily use user names, numbers or whatever. For maintainability though, we recommend a consistent scheme with recognizable labels. On the other hand, there are a number of labels you must avoid, because they will come to conflict with directories that already exist: most notably ''config'', ''extensions'' and ''images''. So before you begin, sit down and write out what your label and database name convention will be. This is trivial if you have just a handful of wikis, but can become very important should you ever grow to hundreds of instances.		And remember, they are just labels. You could just as easily use user names, numbers or whatever. For maintainability though, we recommend a consistent scheme with recognizable labels. On the other hand, there are a number of labels you must avoid, because they will come to conflict with directories that already exist: most notably ''config'', ''extensions'' and ''images''. So before you begin, sit down and write out what your label and database name convention will be. This is trivial if you have just a handful of wikis, but can become very important should you ever grow to hundreds of instances.