Rails::Assets::Manifest

Load all assets in your Rails application from a manifest.json, e.g. generated by webpack-assets-manifest.

This gem does not make any assumption on which tool to use to make your assets not how to configure or invoke it. It only requires a manifest JSON. The manifest must either be a simple string map or must map to objects having a 'src' attribute. Sub-resource integrity is supported too:

{
  "application.css": {
    "src": "2b16adf6f756625a0194.css",
    "integrity": "sha384-/oreyvcV6U6htGZD0fDWR8/Txezke8KhD0QNgHb660hSaW7M+ZzxxuB4Vo+PuAC9"
  },
  "application.js": {
    "src": "2b16adf6f756625a0194.js",
    "integrity": "sha384-iJ55fQQApbQGxWEWSbWStBabi+yNGxZSQy/010+1Dhxl+rymyhGF4NtjUkOsYv7B"
  }
}

This gem does not add new helper methods but extends the existing helpers. SRI is automatically added if available and within a secure context. A crossorigin="anonymous" attribute is automatically added if non is present.

html
  head
    = stylesheet_link_tag 'application', media: 'all'
    = javascript_include_tag 'application'

<link rel="stylesheet" media="all" href="2b16adf6f756625a0194.css" integrity="sha384-/oreyvcV6U6htGZD0fDWR8/Txezke8KhD0QNgHb660hSaW7M+ZzxxuB4Vo+PuAC9" crossorigin="anonymous">
<script src="2b16adf6f756625a0194.js" integrity="sha384-iJ55fQQApbQGxWEWSbWStBabi+yNGxZSQy/010+1Dhxl+rymyhGF4NtjUkOsYv7B" crossorigin="anonymous"></script>

Installation

Add this line to your application's Gemfile:

gem 'rails-assets-manifest'

Usage

The manifest path can be configured e.g. in an environments/*.rb file:

  config.assets_manifest.path = "public/.asset-manifest.json"

If config.cache_classes is set to true the manifest file be loaded once on boot. Assets included with integrity: true will raise an error if the integrity option is missing in the manifest.

Webpack Assets Manifest Example

The following snippet provides an example configuration for thewebpack-assets-manifest plugin to generating a compatible assets manifest file.

new WebpackAssetsManifest({
  integrity: true,
  integrityHashes: ["sha384"],
  writeToDisk: true,
  entrypoints: false,
  entrypointsUseAssets: true,
  publicPath,
  // Ignore a source maps and compressed files.
  customize(e) {
    if (e.key.endsWith(".map") || e.key.endsWith(".gz")) {
      return false;
    }

    return e;
  },
})

Specifying writeToDisk: true allows running the webpack-dev-server as proxy to the Rails application, and still generate correct assets links in Rails code. rails-assets-manifest defaults to using public/assets/assets-manifest.json as the manifest path.

TODO

Override/Join with asset_host URL?

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit specs for your feature so that I do not break it later
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.