1 [[rcs/git]] and other distributed version control systems are all about
2 making it easy to create and maintain copies and branches of a project. And
3 this can be used for all sorts of interesting stuff. Since ikiwiki can use
4 git, let's explore some possibilities for distributed wikis.
10 There are three possible level of decentralisation:
12 0. [[default setup|rcs/git]], no decentralisation
13 1. [[a simple HTML mirror|tips/Git_repository_and_web_server_on_different_hosts/]]
14 2. separate `srcdir`, still requires a central bare repo - uses [[plugins/pinger]]
15 3. completely distinct ikiwiki installs, synchronised with [[plugins/contrib/gitpush]]
17 Here's a graphic overview of those:
19 ### Default setup - one central server
21 [[!img rcs/git/wiki_edit_flow.svg size=400x]]
23 In the default setup, all the resources are stored on the central
24 servers. Users can still clone and edit the git repo by hand and
25 contribute by git, but otherwise all the changes happen on a single
26 web interface. This basic setup is best described in [[rcs/git]].
28 ### Separate webserver and git repository
30 [[!img tips/Git_repository_and_web_server_on_different_hosts/separate-webserver.svg size=400x]]
32 This is the configuration described in
33 [[tips/Git_repository_and_web_server_on_different_hosts]]. The webserver part
34 hosts the HTML files, the ikiwiki [[cgi]] but everything else is on
37 ### Decentralised pinger setup
39 [[!img ping-setup.svg size=400x]]
41 In this configuration, the mirrors all have their own `srcdir`, but
42 still need to push and pull from the same central bare git repo. The
43 [[plugins/pinger]] plugin is used to ping the mirrors from the central
46 Step by step setup instructions for this are detailed below.
48 ### Fully decentralised setup
50 [[!img decentralized_wikis.svg size=400x]]
52 In this configuration, each wiki is fully independent and pushes its
53 changes to other wikis using the [[plugins/contrib/gitpush]] plugin.
57 It follows that setting up a branch of a wiki is just like the fully decentralised mirror above, except
58 we don't want it to push changes back to the origin. The easy way to
59 accomplish this is to clone the origin git repository using a readonly
60 protocol (ie, "git://"). Then you can't push to it.
62 If a page on your branch is modified and other modifications are made to
63 the same page in the origin, a conflict might occur when that change is
64 pulled in. How well will this be dealt with and how to resolve it? I think
65 that the conflict markers will just appear on the page as it's rendered in
66 the wiki, and if you could even resolve the conflict using the web
67 interface. Not 100% sure as I've not gotten into this situation yet.
71 ## Step by step setup instructions
73 The first two ways of setting up ikiwiki are better described in [[setup]] or [[tips/Git_repository_and_web_server_on_different_hosts]]. The remainder of this page describes the latter two more complex distributed setups.
75 Say you have a friend that has already configured a shiny ikiwiki site, and you want to help by creating a mirror. You still need to figure out how to install ikiwiki and everything, hopefully this section will help you with that.
77 ### Installing ikiwiki
79 You need to install the ikiwiki package for the mirror to work. You can use ikiwiki to publish the actual HTML pages elsewhere if you don't plan on letting people edit the wiki, but generally you want the package to be installed on the webserver for editing to work.
81 apt-get install ikiwiki
83 ### Setting up the wiki
85 (!) Optionnally: create a user just for this wiki. Otherwise the wiki will run as your user from here on.
87 We assume your username is `user` and that you will host the wiki under the hostname `mirror.example.com`. The original wiki is at `wiki.example.com`. We also assume that your friend was nice enough to provide a copy of the `.setup` file in the `setup` branch, which is the case for any wiki hosted on [branchable.com](http://branchable.com).
90 # setup srcdir, named source
91 git clone git://wiki.example.com/ source
92 # convenience copy of the setup file
93 git clone -b origin/setup source setup
95 edit ikiwiki.setup # adapt configuration
97 When editing ikiwiki.setup, make sure you change the following entries:
99 cgiurl: http://mirror.example.com/ikiwiki.cgi
100 cgi_wrapper: /var/www/ikiwiki.cgi
101 srcdir: /home/user/source
102 destdir: /var/www/mirror.example.com
103 libdir: /home/user/source/.ikiwiki
104 git_wrapper: /home/user/source/.git/hooks/post-commit
105 git_test_receive_wrapper: /home/user/source/.git/hooks/pre-receive
107 TMPDIR: /home/user/tmp
109 This assumes that your /var/www directory is writable by your user.
111 ### Basic HTML rendering
113 You should already be able to make a plain HTML rendering of the wiki:
115 ikiwiki --setup ikiwiki.setup
117 ### Webserver configuration
119 You will also need a webserver to serve the content in the `destdir`
120 defined above. We assume you will configure a virtual host named `mirror.example.com`. Here are some examples on how to do those, see [[!iki setup]] and [[!iki tips/dot_cgi]] for complete documentation.
122 Note that this will also configure CGI so that people can edit the wiki. Note that this configuration may involve timeouts if the main site is down, as ikiwiki will attempt to push to the central git repository at every change.
124 #### Apache configuration
127 ServerName mirror.example.com:80
128 DocumentRoot /var/www/mirror.example.com
129 <Directory /var/www/mirror.example.com>
130 Options Indexes MultiViews ExecCGI
135 ScriptAlias /ikiwiki.cgi /var/www/ikiwiki.cgi
136 ErrorDocument 404 "/ikiwiki.cgi"
139 #### Nginx configuration
142 root /var/www/mirror.example.com/;
143 index index.html index.htm;
144 server_name mirror.example.com;
147 try_files $uri $uri/ /index.html;
149 location /ikiwiki.cgi {
150 fastcgi_pass unix:/tmp/fcgi.socket;
151 fastcgi_index ikiwiki.cgi;
152 fastcgi_param SCRIPT_FILENAME /var/www/ikiwiki.cgi;
153 fastcgi_param DOCUMENT_ROOT /var/www/mirror.example.com;
154 include /etc/nginx/fastcgi_params;
158 Start this process as your own user (or the user that has write access
159 to `srcdir`, `destdir`, etc):
161 spawn-fcgi -s /tmp/fcgi.socket -n -- /usr/sbin/fcgiwrap
165 chmod a+w /tmp/fcgi.socket
167 ### Enable the pinger functionality
169 At this point, you need to enable the pinger functionality to make sure that changes on the central server propagate to your mirror.
171 This assumes a central wiki that exposes its git
172 repository and has the [[plugins/pinger]] plugin enabled. Enable the
173 [[plugins/pingee]] plugin in your configuration, and edit the origin wiki,
174 adding a ping directive for your mirror:
176 \[[!ping from="http://thewiki.com/"
177 to="http://mymirror.com/ikiwiki.cgi?do=ping"]]
179 The "from" parameter needs to be the url to the origin wiki. The "to" parameter
180 is the url to ping on your mirror. This can be done basically in any page.
182 Now whenever the main wiki is edited, it will ping your mirror, which will
183 pull the changes from "origin" using git, and update itself. It could, in
184 turn ping another mirror, etc.
186 And if someone edits a page on your mirror, it will "git push origin",
187 committing the changes back to the origin git repository, and updating the
188 origin mirror. Assuming you can push to that git repository. If you can't,
189 and you want a mirror, and not a branch, you should disable web edits on
190 your mirror. (You could also point the cgiurl for your mirror at the origin
191 wiki if you do not want to incur that overhead or do not want to, or can't, run a CGI.)
193 ### Announcing the mirror
195 Once your mirror works, you can also add it to the list of mirrors. You can ask the mirror where you take it from (and why not, all mirrors) to add it to their setup file. As an example, here's the configuration for the first mirror:
198 example: https://wiki.example.com/
200 The [[plugins/mirrorlist]] plugin of course needs to be enabled for this to work.
202 ### Fully decentralized configuration
204 In the above configuration, the master git repository is still on the main site. If that site goes down, there will be delays when editing the wiki mirror. It could also simply fail because it will not be able to push the changes to the master git repo. An alternative is to setup a local bare repository that is synced with the master.
206 At the setup step, you need to create *two* git repositories on the mirror:
209 # setup base repository, named source.git
210 git clone --bare git://wiki.example.com/ source.git
211 # setup srcdir, named source
213 # convenience copy of the setup file
214 git clone -b origin/setup source.git setup
216 edit ikiwiki.setup # adapt configuration
218 The following entries will be different from the above setup file:
220 git_wrapper: /home/user/source.git/hooks/post-commit
221 git_test_receive_wrapper: /home/user/source.git/hooks/pre-receive
223 To do this, the mirror needs to push back to the master, using the [[plugins/contrib/gitpush]] plugin:
226 - git://wiki.example.com/
228 This will ensure that commits done on the mirror will propagate back to the master.
232 Another guide is the [[tips/laptop_wiki_with_git]] guide. To get a
233 better understanding of how ikiwiki works, see [[rcs/git]].
235 [This](http://piny.be/jrayhawk/notes/ikiwiki_creation/) may also be of
236 use if the above doesn't work.