1 Ikiwiki's plugin interface allows all kinds of useful [[plugins]] to be
2 written to extend ikiwiki in many ways. Despite the length of this page,
3 it's not really hard. This page is a complete reference to everything a
4 plugin might want to do. There is also a quick [[tutorial]].
10 Most ikiwiki [[plugins]] are written in perl, like ikiwiki. This gives the
11 plugin full access to ikiwiki's internals, and is the most efficient.
12 However, plugins can actually be written in any language that supports XML
13 RPC. These are called [[external]] plugins.
15 A plugin written in perl is a perl module, in the `IkiWiki::Plugin`
16 namespace. The name of the plugin is typically in lowercase, such as
17 `IkiWiki::Plugin::inline`. Ikiwiki includes a `IkiWiki::Plugin::skeleton`
18 that can be fleshed out to make a useful plugin.
19 `IkiWiki::Plugin::pagecount` is another simple example. All perl plugins
20 should `use IkiWiki` to import the ikiwiki plugin interface. It's a good
21 idea to include the version number of the plugin interface that your plugin
22 expects: `use IkiWiki 2.00`.
24 An external plugin is an executable program. It can be written in any
25 language. Its interface to ikiwiki is via XML RPC, which it reads from
26 ikiwiki on its standard input, and writes to ikiwiki on its standard
27 output. For more details on writing external plugins, see [[external]].
29 Despite these two types of plugins having such different interfaces,
30 they're the same as far as how they hook into ikiwiki. This document will
31 explain how to write both sorts of plugins, albeit with an emphasis on perl
36 One thing to keep in mind when writing a plugin is that ikiwiki is a wiki
37 *compiler*. So plugins influence pages when they are built, not when they
38 are loaded. A plugin that inserts the current time into a page, for
39 example, will insert the build time. Also, as a compiler, ikiwiki avoids
40 rebuilding pages unless they have changed, so a plugin that prints some
41 random or changing thing on a page will generate a static page that won't
42 change until ikiwiki rebuilds the page for some other reason, like the page
45 ## Registering plugins
47 Plugins should, when imported, call `hook()` to hook into ikiwiki's
48 processing. The function uses named parameters, and use varies depending on
49 the type of hook being registered -- see below. Note that a plugin can call
50 the function more than once to register multiple hooks. All calls to
51 `hook()` should be passed a "type" parameter, which gives the type of
52 hook, a "id" paramter, which should be a unique string for this plugin, and
53 a "call" parameter, which tells what function to call for the hook.
55 An optional "last" parameter, if set to a true value, makes the hook run
56 after all other hooks of its type. Useful if the hook depends on some other
61 In roughly the order they are called.
65 hook(type => "getopt", id => "foo", call => \&getopt);
67 This allows for plugins to perform their own processing of command-line
68 options and so add options to the ikiwiki command line. It's called during
69 command line processing, with @ARGV full of any options that ikiwiki was
70 not able to process on its own. The function should process any options it
71 can, removing them from @ARGV, and probably recording the configuration
72 settings in %config. It should take care not to abort if it sees
73 an option it cannot process, and should just skip over those options and
78 hook(type => "checkconfig", id => "foo", call => \&checkconfig);
80 This is useful if the plugin needs to check for or modify ikiwiki's
81 configuration. It's called early in the startup process. The
82 function is passed no values. It's ok for the function to call
83 `error()` if something isn't configured right.
87 hook(type => "needsbuild", id => "foo", call => \&needsbuild);
89 This allows a plugin the manipulate the list of files that need to be
90 built when the wiki is refreshed. The function is passed a reference to an
91 array of pages that will be rebuilt, and can modify the array, either
92 adding or removing files from it.
96 hook(type => "filter", id => "foo", call => \&filter);
98 Runs on the raw source of a page, before anything else touches it, and can
99 make arbitrary changes. The function is passed named parameters "page",
100 "destpage", and "content". It should return the filtered content.
104 Adding a [[PreProcessorDirective]] is probably the most common use of a
107 hook(type => "preprocess", id => "foo", call => \&preprocess);
109 Replace "foo" with the command name that will be used inside brackets for
110 the preprocessor directive.
112 Each time the directive is processed, the referenced function (`preprocess`
113 in the example above) is called, and is passed named parameters. A "page"
114 parameter gives the name of the page that embedded the preprocessor
115 directive, while a "destpage" parameter gives the name of the page the
116 content is going to (different for inlined pages), and a "preview"
117 parameter is set to a true value if the page is being previewed. All
118 parameters included in the directive are included as named parameters as
119 well. Whatever the function returns goes onto the page in place of the
122 An optional "scan" parameter, if set to a true value, makes the hook be
123 called during the preliminary scan that ikiwiki makes of updated pages,
124 before begining to render pages. This parameter should be set to true if
125 the hook modifies data in `%links`. Note that doing so will make the hook
126 be run twice per page build, so avoid doing it for expensive hooks.
128 Note that if the [[htmlscrubber]] is enabled, html in
129 [[PreProcessorDirective]] output is sanitised, which may limit what your
130 plugin can do. Also, the rest of the page content is not in html format at
131 preprocessor time. Text output by a preprocessor directive will be
132 linkified and passed through markdown (or whatever engine is used to htmlize
133 the page) along with the rest of the page.
137 hook(type => "htmlize", id => "ext", call => \&htmlize);
139 Runs on the raw source of a page and turns it into html. The id parameter
140 specifies the filename extension that a file must have to be htmlized using
141 this plugin. This is how you can add support for new and exciting markup
142 languages to ikiwiki.
144 The function is passed named parameters: "page" and "content" and should
145 return the htmlized content.
149 hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
151 [[Templates|wikitemplate]] are filled out for many different things in
152 ikiwiki, like generating a page, or part of a blog page, or an rss feed, or
153 a cgi. This hook allows modifying the variables available on those
154 templates. The function is passed named parameters. The "page" and
155 "destpage" parameters are the same as for a preprocess hook. The "template"
156 parameter is a [[cpan HTML::Template]] object that is the template that
157 will be used to generate the page. The function can manipulate that
160 The most common thing to do is probably to call `$template->param()` to add
161 a new custom parameter to the template.
165 hook(type => "templatefile", id => "foo", call => \&templatefile);
167 This hook allows plugins to change the [[template|wikitemplate]] that is
168 used for a page in the wiki. The hook is passed a "page" parameter, and
169 should return the name of the template file to use, or undef if it doesn't
170 want to change the default ("page.tmpl"). Template files are looked for in
171 /usr/share/ikiwiki/templates by default.
175 hook(type => "sanitize", id => "foo", call => \&sanitize);
177 Use this to implement html sanitization or anything else that needs to
178 modify the body of a page after it has been fully converted to html.
180 The function is passed named parameters: "page" and "content", and
181 should return the sanitized content.
185 hook(type => "format", id => "foo", call => \&format);
187 The difference between format and sanitize is that sanitize only acts on
188 the page body, while format can modify the entire html page including the
189 header and footer inserted by ikiwiki, the html document type, etc.
191 The function is passed named parameters: "page" and "content", and
192 should return the formatted content.
196 hook(type => "delete", id => "foo", call => \&delete);
198 Each time a page or pages is removed from the wiki, the referenced function
199 is called, and passed the names of the source files that were removed.
203 hook(type => "change", id => "foo", call => \&render);
205 Each time ikiwiki renders a change or addition (but not deletion) to the
206 wiki, the referenced function is called, and passed the names of the
207 source files that were rendered.
211 hook(type => "cgi", id => "foo", call => \&cgi);
213 Use this to hook into ikiwiki's cgi script. Each registered cgi hook is
214 called in turn, and passed a CGI object. The hook should examine the
215 parameters, and if it will handle this CGI request, output a page (including the http headers) and
216 terminate the program.
220 hook(type => "auth", id => "foo", call => \&auth);
222 This hook can be used to implement a different authentication method than
223 the standard web form. When a user needs to be authenticated, each registered
224 auth hook is called in turn, and passed a CGI object and a session object.
226 If the hook is able to authenticate the user, it should set the session
227 object's "name" parameter to the authenticated user's name. Note that
228 if the name is set to the name of a user who is not registered,
229 a basic registration of the user will be automatically performed.
233 hook(type => "sessioncgi", id => "foo", call => \&sessioncgi);
235 Unlike the cgi hook, which is run as soon as possible, the sessioncgi hook
236 is only run once a session object is available. It is passed both a CGI
237 object and a session object. To check if the user is in fact signed in, you
238 can check if the session object has a "name" parameter set.
242 hook(type => "canedit", id => "foo", call => \&pagelocked);
244 This hook can be used to implement arbitrary access methods to control when
245 a page can be edited using the web interface (commits from revision control
246 bypass it). When a page is edited, each registered canedit hook is called
247 in turn, and passed the page name, a CGI object, and a session object.
249 If edit can proceed, the hook should return "". If the edit is not allowed
250 by this hook, the hook should return an error message for the user to see.
251 If the hook has no opinion about whether the edit can proceed, return
252 `undef`, and the next plugin will be asked to decide.
256 hook(type => "formbuilder_setup", id => "foo", call => \&formbuilder_setup);
257 hook(type => "formbuilder", id => "foo", call => \&formbuilder);
259 These hooks allow tapping into the parts of ikiwiki that use [[cpan
260 CGI::FormBuilder]] to generate web forms. These hooks are passed named
261 parameters: `cgi`, `session`, `form`, and `buttons`. These are, respectively,
262 the `CGI` object, the user's `CGI::Session`, a `CGI::FormBuilder`, and a
263 reference to an array of names of buttons to go on the form.
265 Each time a form is set up, the `formbuilder_setup` hook is called.
266 Typically the `formbuilder_setup` hook will check the form's title, and if
267 it's a form that it needs to modify, will call various methods to
268 add/remove/change fields, tweak the validation code for the fields, etc. It
269 will not validate or display the form.
271 Form validation and display can be overridden by the formbuilder hook.
272 By default, ikiwiki will do a basic validation and display of the form,
273 but if this hook is registered, it will stop that and let the hook take
278 hook(type => "savestate", id => "foo", call => \&savestate);
280 This hook is called wheneven ikiwiki normally saves its state, just before
281 the state is saved. The function can save other state, modify values before
286 To import the ikiwiki plugin interface:
290 This will import several variables and functions into your plugin's
291 namespace. These variables and functions are the ones most plugins need,
292 and a special effort will be made to avoid changing them in incompatible
293 ways, and to document any changes that have to be made in the future.
295 Note that IkiWiki also provides other variables and functions that are not
296 exported by default. No guarantee is made about these in the future, so if
297 it's not exported, the wise choice is to not use it.
301 A plugin can access the wiki's configuration via the `%config`
302 hash. The best way to understand the contents of the hash is to look at
303 [[ikiwiki.setup]], which sets the hash content to configure the wiki.
307 If your plugin needs to access data about other pages in the wiki. It can
308 use the following hashes, using a page name as the key:
310 * `%links` lists the names of each page that a page links to, in an array
312 * `%destsources` contains the name of the source file used to create each
314 * `%pagesources` contains the name of the source file for each page.
316 Also, the %IkiWiki::version variable contains the version number for the
319 ### Library functions
323 Hook into ikiwiki's processing. See the discussion of hooks above.
325 Note that in addition to the named parameters described above, a parameter
326 named `no_override` is supported, If it's set to a true value, then this hook
327 will not override any existing hook with the same id. This is useful if
328 the id can be controled by the user.
332 Logs a debugging message. These are supressed unless verbose mode is turned
337 Aborts with an error message. If the second parameter is passed, it is a
338 function that is called after the error message is printed, to do any final
341 Note that while any plugin can use this for a fatal error, plugins should
342 try to avoid dying on bad input, as that will halt the entire wiki build
343 and make the wiki unusable. So for example, if a [[PreProcessorDirective]]
344 is passed bad parameters, it's better to return an error message, which can
345 appear on the wiki page, rather than calling error().
349 Creates and returns a [[cpan HTML::Template]] object. The first parameter
350 is the name of the file in the template directory. The optional remaining
351 parameters are passed to `HTML::Template->new`.
355 Passed a page name, returns the base name that will be used for a the html
356 page created from it. (Ie, it appends ".html".)
358 #### `add_depends($$)`
360 Makes the specified page depend on the specified [[PageSpec]].
362 #### `pagespec_match($$;@)`
364 Passed a page name, and [[PageSpec]], returns true if the [[PageSpec]]
367 Additional named parameters can be passed, to further limit the match.
368 The most often used is "location", which specifies the location the
369 PageSpec should match against. If not passed, relative PageSpecs will match
370 relative to the top of the wiki.
374 Given a page and the text of a link on the page, determine which
375 existing page that link best points to. Prefers pages under a
376 subdirectory with the same name as the source page, failing that
377 goes down the directory tree to the base looking for matching
378 pages, as described in [[SubPage/LinkingRules]].
380 #### `htmllink($$$;@)`
382 Many plugins need to generate html links and add them to a page. This is
383 done by using the `htmllink` function. The usual way to call
386 htmllink($page, $page, $link)
388 Why is `$page` repeated? Because if a page is inlined inside another, and a
389 link is placed on it, the right way to make that link is actually:
391 htmllink($page, $destpage, $link)
393 Here `$destpage` is the inlining page. A `destpage` parameter is passed to
394 some of the hook functions above; the ones that are not passed it are not used
395 during inlining and don't need to worry about this issue.
397 After the three required parameters, named parameters can be used to
398 control some options. These are:
400 * noimageinline - set to true to avoid turning links into inline html images
401 * forcesubpage - set to force a link to a subpage
402 * linktext - set to force the link text to something
403 * anchor - set to make the link include an anchor
404 * rel - set to add a rel attribute to the link.
408 Given a filename, reads and returns the entire file.
410 The optional second parameter, if set to a true value, makes the file be read
413 A failure to read the file will result in it dying with an error.
415 #### `writefile($$$;$$)`
417 Given a filename, a directory to put it in, and the file's content,
420 The optional fourth parameter, if set to a true value, makes the file be
421 written in binary mode.
423 The optional fifth parameter can be used to pass a function reference that
424 will be called to handle writing to the file. The function will be called
425 and passed a file descriptor it should write to, and an error recovery
426 function it should call if the writing fails. (You will not normally need to
429 A failure to write the file will result in it dying with an error.
431 If the destination directory doesn't exist, it will first be created.
433 #### `will_render($$)`
435 Given a page name and a destination file name (not including the base
436 destination directory), register that the page will result in that file
437 being rendered. It's important to call this before writing to any file in
438 the destination directory.
442 Given the name of a source file, returns the type of page it is, if it's
443 a type that ikiwiki knowns how to htmlize. Otherwise, returns undef.
447 Given the name of a source file, returns the name of the wiki page
448 that corresponds to that file.
452 Given the name of a source file in the wiki, searches for the file in
453 the source directory and the underlay directory, and returns the full
454 path to the first file found.
456 #### `displaytime($)`
458 Given a time, formats it for display.
462 This is the standard gettext function, although slightly optimised.
466 Construct a relative url to the first parameter from the page named by the
467 second. The first parameter can be either a page name, or some other
468 destination file, as registered by `will_render`.
470 #### `targetpage($$)`
472 Passed a page and an extension, returns the filename that page will be
477 ikiwiki's support for [[revision_control_systems|rcs]] also uses pluggable
478 perl modules. These are in the `IkiWiki::RCS` namespace, for example
481 Each RCS plugin must support all the `IkiWiki::rcs_*` functions.
482 See IkiWiki::RCS::Stub for the full list of functions. It's ok if
483 `rcs_getctime` does nothing except for throwing an error.
485 See [[RCS_details|rcs/details]] for some more info.
489 It's also possible to write plugins that add new functions to
490 [[PageSpecs|PageSpec]]. Such a plugin should add a function to the
491 IkiWiki::PageSpec package, that is named `match_foo`, where "foo()" is
492 how it will be accessed in a [[PageSpec]]. The function will be passed
493 two parameters: The name of the page being matched, and the thing to match
494 against. It may also be passed additional, named parameters. It should return
495 a IkiWiki::SuccessReason object if the match succeeds, or an
496 IkiWiki::FailReason object if the match fails.