ep_webpack

Etherpad plugin to bundle files using webpack, thus improving the performance of file loading on client-side.

Why should you use this plugin?

Sometimes the browser takes FOREVER to load Etherpad editor, especially on instances with a lot of plugins, and with each plugin using a lot of files. On an instance with 30+ plugins and 400+ files to load, it can take up to a minute for the pad to be ready to be edited.

By installing this plugin you can speed up this process a lot:

• time to load without ep_webpack: 48s (411 requests);
• time to load with ep_webpack bundling only JS files: 21s (177 requests);
• time to load with ep_webpack bundling JS + CSS files: 14s (57 requests);

Features:

• Speeds up Etherpad loading on browser by 70%;
• Bundle all plugins by default, but allow plugins to be ignored by webpack
• Bundled files are automatically updated on local environment
• Minimize files on non-dev environments;
• Allow bundle of CSS files;
• Allow styling plugins using SASS;
• Provide default webpack configuration, but allow them to be customized;
• Use webpack v.4;

Development mode

This plugin has a watch mode, so you don't need to restart Etherpad every time you change something on the plugin files. To use it, just go the the folder where ep_webpack is installed, and run the watch command with the target webpack.config.*.js file for your settings:

cd path/to/etherpad-lite/node_modules/ep_webpack && npm run watch -- --config './webpack.config-withMinifyAndCss.js'

If Docker is your thing, you can add this to your docker-compose.yml:

  webpack:
    # ideally, use the same image used by Etherpad containers
    image: node:8.9.0
    environment:
      NODE_ENV: "development"
    command: bash -c "cd /etherpad-lite/node_modules/ep_webpack && npm run watch -- --config './webpack.config-withMinifyAndCss.js'"
    volumes:
      - path/to/etherpad-lite/:/etherpad-lite/

How does this plugin work?

Here's a short explanation of what ep_webpack does to bundle all plugins and serve a single file to the client:

1. on the first server-side hook after plugins are loaded (loadSettings), we get the original list of plugins & their hooks on plugins.parts (defined on ep_etherpad-lite/static/js/pluginfw/plugins);
2. for each file containing a client-side hook, we import it on a single file (ep_webpack/static/js/index.js). This allows us to use a single entry point for all dependencies;
3. then, we generate the bundle using webpack. A new file is created: ep_webpack/static/dist/js/index;
4. after that, for each client-side hook, we override the path for its definition with the generated file, making Etherpad call a single JS file for all the plugins it loads on the client.

If CSS files should be bundled, some extra steps are executed on the flow mentioned above:

1. we try to execute all aceEditorCSS hooks in order to get the list of CSS files, and we import them together with the JS single entry point (ep_webpack/static/js/index.js);
2. when we run webpack, another file is created: ep_webpack/static/dist/css/all.css;
3. finally, all aceEditorCSS hooks are removed from the plugins, and the only hook of that type will point to the bundled CSS file.

Available customizations

Ignore a plugin

Sometimes an installed plugin is not ready to be used with webpack, so it is possible to ignore it when building the bundle: just include the part(s) of the plugin on your settings.json (notice that you need to exclude the parts, not the plugins):

  "ep_webpack": {
    /* Ignores parts (not plugins) not ready to be bundled */
    "ignoredParts": ["autocomp", "comments_page"]
  }

Bundle CSS files too

Warning: this is an advanced customization and might not work with all the plugins

If you also want to bundle CSS files, you need to turn this feature on on the settings.json:

  "ep_webpack": {
    /* Bundle CSS files too */
    "bundleCSS": true
  }

If you enable this feature and start to see error messages on the server console, take a look on the Troubleshooting session.

Use your own set of webpack configs

ep_webpack comes with a set of default configs to bundle the files, but you can override them by defining a JS object that will be used when bundling files:

  "ep_webpack": {
    /*
     * Path to the custom webpack config file. Must be an absolute path,
     * or relative to etherpad-lite/node_modules/ep_webpack/.
     */
    "customWebpackConfigFile": "path/to/your/webpack.config.js"
  }

Troubleshooting

The most common type of error is when trying to bundle CSS files. If you see an error message like Could not load the list of CSS files from aceEditorCSS hook, so its files won't be bundled., you'll need to make some changes in order to be able to bundle the CSS files:

• Extract the hook into a separated file: [TL;DR:] the most effective way is to change the plugin code in order to extract the aceEditorCSS hook into a separated JS file. See this pull request as an example.

  [Long story:] Usually the error when executing the CSS hook happens because the JS file where it is defined needs to be run on the browser context, which is not where it is run when we're bundling the files. For example, the JS file might require jQuery:

  var $ = require('ep_etherpad-lite/static/js/rjquery').$;

  This will certainly raise an error, as jQuery needs window to be defined, and it is not defined on the server side.

  By putting the aceEditorCSS hook in a separated JS file, you'll be able to require it both on client and on server sides without any issue, as this hooks only needs to return an array of strings.

• Add the problematic plugin to the list of ignored parts: if you can't submit a pull request to extract aceEditorCSS into a separated file, you can exclude the plugin from the list of bundled parts, so at least the other plugins will be able to be bundled;

• Disable CSS bundling: finally, you can disable the CSS bundling entirely, which will allow you to keep bundling at least the JS files;

Next improvements

Want to help? Here's a list of future improvements this plugins might have:

• [ ] Re-create bundles when plugins installed/uninstalled via /admin route;
• [ ] Bundle vendor files (jQuery, underscore, etc) into a separated chunk, in order to improve cache usage. From webpack docs:

  It's also good practice to extract third-party libraries, such as lodash or react, to a separate vendor chunk as they are less likely to change than our local source code. This step will allow clients to request even less from the server to stay up to date.

• [ ] Include Etherpad core files to the bundle (this looks like a hard feature to implement);