doc/plugins.md
Etherpad allows you to extend its functionality with plugins. A plugin registers hooks (functions) for certain events (thus certain features) in Etherpad to execute its own functionality based on these events.
Publicly available plugins can be found in the npm registry (see
https://npmjs.org). Etherpad's naming convention for plugins is to prefix your
plugins with ep_. So, e.g. it's ep_flubberworms. Thus you can install
plugins from npm, using pnpm run plugins install ep_flubberworms in Etherpad's root directory.
Also see wiki article for more info.
You can also browse to http://yourEtherpadInstan.ce/admin/plugins, which will
list all installed plugins and those available on npm. It even provides
functionality to search through all available plugins.
Ideally a plugin has the following folder structure:
ep_<plugin>/
├ .github/
│ └ workflows/
│ └ npmpublish.yml ◄─ GitHub workflow to auto-publish on push
├ static/
│ ├ css/ ◄─ static .css files
│ ├ images/ ◄─ static image files
│ ├ js/
│ │ └ index.js ◄─ static client-side code
│ └ tests/
│ ├ backend/
│ │ └ specs/ ◄─ backend (server) tests
│ └ frontend/
│ └ specs/ ◄─ frontend (client) tests
├ templates/ ◄─ EJS templates (.html, .js, .css, etc.)
├ locales/
│ ├ en.json ◄─ English (US) strings
│ └ qqq.json ◄─ optional hints for translators
├ .github/workflows/ ◄─ CI workflows (backend / frontend tests, npm publish)
├ LICENSE
├ README.md
├ ep.json ◄─ Etherpad plugin definition
├ index.js ◄─ server-side code
├ package.json
└ package-lock.json
If your plugin includes client-side hooks, put them in static/js/. If you're
adding in CSS or image files, you should put those files in static/css/ and
static/image/, respectively, and templates go into templates/. Translations
go into locales/. Tests go in static/tests/backend/specs/ and
static/tests/frontend/specs/.
A Standard directory structure like this makes it easier to navigate through
your code. That said, do note, that this is not actually required to make your
plugin run. If you want to make use of our i18n system, you need to put your
translations into locales/, though, in order to have them integrated. (See
"Localization" for more info on how to localize your plugin.)
Your plugin definition goes into ep.json. In this file you register your hook
functions, indicate the parts of your plugin and the order of execution. (A
documentation of all available events to hook into can be found in chapter
hooks.)
{
"parts": [
{
"name": "nameThisPartHoweverYouWant",
"hooks": {
"authenticate": "ep_<plugin>/<file>:functionName1",
"expressCreateServer": "ep_<plugin>/<file>:functionName2"
},
"client_hooks": {
"acePopulateDOMLine": "ep_<plugin>/<file>:functionName3"
}
}
]
}
A hook function registration maps a hook name to a hook function specification.
The hook function specification looks like ep_example/file.js:functionName. It
consists of two parts separated by a colon: a module name to require() and the
name of a function exported by the named module. See
module.exports
for how to export a function.
For the module name you can omit the .js suffix, and if the file is index.js
you can use just the directory name. You can also omit the module name entirely,
in which case it defaults to the plugin name (e.g., ep_example).
You can also omit the function name. If you do, Etherpad will look for an
exported function whose name matches the name of the hook (e.g.,
authenticate).
If either the module name or the function name is omitted (or both), the colon
may also be omitted unless the provided module name contains a colon. (So if the
module name is C:\foo.js then the hook function specification with the
function name omitted would be "C:\\foo.js:".)
Examples: Suppose the plugin name is ep_example. All of the following are
equivalent, and will cause the authorize hook to call the exports.authorize
function in index.js from the ep_example plugin:
"authorize": "ep_example/index.js:authorize""authorize": "ep_example/index.js:""authorize": "ep_example/index.js""authorize": "ep_example/index:authorize""authorize": "ep_example/index:""authorize": "ep_example/index""authorize": "ep_example:authorize""authorize": "ep_example:""authorize": "ep_example""authorize": ":authorize""authorize": ":""authorize": ""There are server hooks, which will be executed on the server (e.g.
expressCreateServer), and there are client hooks, which are executed on the
client (e.g. acePopulateDomLine). Be sure to not make assumptions about the
environment your code is running in, e.g. don't try to access process, if you
know your code will be run on the client, and likewise, don't try to access
window on the server...
When you install a client-side plugin (e.g. one that implements at least one
client-side hook), the plugin name is added to the class attribute of the div
#editorcontainerbox in the main window. This gives you the opportunity of
tuning the appearance of the main UI in your plugin.
For example, this is the markup with no plugins installed:
<div id="editorcontainerbox" class="">
and this is the contents after installing someplugin:
<div id="editorcontainerbox" class="ep_someplugin">
This feature was introduced in Etherpad 1.8.
As your plugins become more and more complex, you will find yourself in the need
to manage dependencies between plugins. E.g. you want the hooks of a certain
plugin to be executed before (or after) yours. You can also manage these
dependencies in your plugin definition file ep.json:
{
"parts": [
{
"name": "onepart",
"pre": [],
"post": ["ep_onemoreplugin/partone"]
"hooks": {
"storeBar": "ep_monospace/plugin:storeBar",
"getFoo": "ep_monospace/plugin:getFoo",
}
},
{
"name": "otherpart",
"pre": ["ep_my_example/somepart", "ep_otherplugin/main"],
"post": [],
"hooks": {
"someEvent": "ep_my_example/otherpart:someEvent",
"another": "ep_my_example/otherpart:another"
}
}
]
}
Usually a plugin will add only one functionality at a time, so it will probably
only use one part definition to register its hooks. However, sometimes you
have to put different (unrelated) functionalities into one plugin. For this you
will want use parts, so other plugins can depend on them.
The "pre" and "post" definitions, affect the order in which parts of a
plugin are executed. This ensures that plugins and their hooks are executed in
the correct order.
"pre" lists parts that must be executed before the defining part. "post"
lists parts that must be executed after the defining part.
You can, on a basic level, think of this as double-ended dependency listing. If
you have a dependency on another plugin, you can make sure it loads before yours
by putting it in "pre". If you are setting up things that might need to be
used by a plugin later, you can ensure proper order by putting it in "post".
Note that it would be far more sane to use "pre" in almost any case, but if
you want to change config variables for another plugin, or maybe modify its
environment, "post" could definitely be useful.
Also, note that dependencies should also be listed in your package.json, so
they can be npm install'd automagically when your plugin gets installed.
Your plugin must also contain a package definition file, called package.json, in the project root - this file contains various metadata relevant to your plugin, such as the name and version number, author, project hompage, contributors, a short description, etc. If you publish your plugin on npm, these metadata are used for package search etc., but it's necessary for Etherpad plugins, even if you don't publish your plugin.
{
"name": "ep_PLUGINNAME",
"version": "0.0.1",
"description": "DESCRIPTION",
"author": "USERNAME (REAL NAME) <[email protected]>",
"contributors": [],
"dependencies": {"MODULE": "0.3.20"},
"engines": {"node": ">=22.0.0"}
}
If your plugin adds or modifies the front end HTML (e.g. adding buttons or
changing their functions), you should put the necessary HTML code for such
operations in templates/, in files of type ".ejs", since Etherpad uses EJS for
HTML templating. See the following link for more information about EJS:
https://github.com/visionmedia/ejs.
Plugins can ride the existing padoptions COLLABROOM rail to store
pad-wide settings — broadcast to every connected client, persisted with the
pad, and honored by enforceSettings — instead of inventing their own
message type and storage. The model matches how enablePadWideSettings
works for native toggles like sticky chat or line numbers.
let padOptionsPluginPassthrough = false;
try {
// The require throws on Etherpad versions that predate this capability;
// plugins should degrade gracefully (typically falling back to a per-user
// cookie toggle) when the flag is missing.
padOptionsPluginPassthrough =
require('ep_etherpad-lite/node/utils/PluginCapabilities')
.padOptionsPluginPassthrough === true;
} catch (_e) { /* older core */ }
The flag means the core has the passthrough patch available. Whether it is actually enabled at runtime is a separate per-instance setting — see below.
The passthrough is gated by settings.enablePluginPadOptions, default
false. Operators must opt in via settings.json:
{
"enablePluginPadOptions": true
}
When enabled, the server reflects the value to every client via
clientVars.enablePluginPadOptions so plugins can detect both capable
(static) and active (per-pad request) at the same point.
Plugins must use keys matching /^ep_[a-z0-9_]+$/. The recommended pattern
is ep_<plugin_name> (e.g. ep_table_of_contents); compose multiple
pad-wide settings under one key as a plain object:
pad.changePadOption('ep_my_plugin', {enabled: true, depth: 3});
The server passes through any matching key on the existing padoptions
message, persists it with the pad, and broadcasts it to every connected
client. pad.padOptions.ep_my_plugin reflects the latest value on every
client.
Server-side Pad.normalizePadSettings() enforces three rules on every
plugin-namespaced key:
JSON.stringify (no functions, symbols,
BigInt, or circular references).ep_* values per pad must fit within 256 KB.Values that fail any of these rules are dropped with a console.warn; the
rest of the settings round-trip cleanly. The caps prevent a misbehaving
plugin from bloating the persisted pad payload or the COLLABROOM
broadcast.
Etherpad allows you to easily create front-end tests for plugins.
%your_plugin%/static/tests/frontend/specs%etherpad_root_folder%/frontend/tests/specs.)