Integrates Eyeglass and the broccoli build system.
JavaScript CSS
Latest commit f9fbe27 Dec 14, 2016 @chriseppstein chriseppstein release 2.4.1


broccoli-eyeglass is a broccoli plugin that compiles .scss and .sass files with libsass and uses eyeglass for project and sass module support.


npm install --save-dev broccoli-eyeglass


In your Brocfile.js:

var compileSass = require('broccoli-eyeglass');

var outputDirectory = "dist";
var options = {
  cssDir: "assets/css",
  fullException: false
var outputTree = new compileSass(inputTrees, options);
  • inputTrees: An array of trees that act as the include paths for libsass. If you have a single tree, pass [tree]. All sass files in these trees that are not prefixed with an underscore (a.k.a. a partial), will be compiled into a single output directory. Use the node-sass includePaths option to make other directories available for import without compiling them to css. Note that eyeglass will make sure that all your eyeglass-compatible sass modules can be imported.

  • options: Except for the options that are specific to this plugin. All the rest are passed through eyeglass and then to node-sass.

Note: that the following node-sass options are managed by this plugin and must not be provided: file, data, outFile


The following options are specific to this plugin:

  • assets - Optional. A string or array of strings indicating the subdirectories where assets for the project can be found. This calls eyeglass.assets.addSource for each directory specified. If the options passed for these are not sufficient, use the configureEyeglass callback to call addSource with the options you need.
  • assetsHttpPrefix - The subdirectory that assets are in relative to the httpRoot when generating urls to them.
  • configureEyeglass - Optional. A callback function that is passed the eyeglass instance for a file so that it can be manipulated before compiling the Sass file. The arguments passed are:

    • eyeglass - The eyeglass instance.
    • sass - the node-sass instance.
    • details - the compilation details object which provides information about what is being compiled. See below for more information about the compilation details.
  • cssDir - Required. The directory where CSS files should be written relative to the build output directory.
  • discover - When true, will discover sass files to compile that are found in the sass directory. Defaults to true unless sourceFiles are specified.
  • sassDir - The directory to look for scss files to compile. Defaults to tree root.
  • fullException - When set to true, instead of generating a build error, the css output file will be written such that it displays a compilation failure in the browser. This is useful during development but should not be used for production builds. (Not yet implemented)
  • renderSync - Force sass rendering to use node-sass's synchronous rendering. Defaults to false.
  • relativeAssets - Whether to render relative links to assets. Defaults to false.
  • sourceFiles - Array of file names or glob patterns (relative to the sass directory) that should be compiled. Note that file names must include the file extension (unlike @import in Sass). E.g.: ['application.scss']
  • persistentCache - String. Set to the name of your application so that your cache is isolated from other broccoli-eyeglass based builds. When falsy, persistent caching is disabled.
  • maxListeners - Integer. Set to the maximum number of listeners your use of eyeglass compiler needs. Defaults to 10. Note: do not set yourself as eyeglass has its own listeners it uses internally.
  • optionsGenerator - Function that accepts four arguments:

    • sassFile - The sass file being compiled.
    • cssFile - The place where broccoli-eyeglass plans to write the cssFile relative to the build output directory.
    • options - The compilation options that will be passed to eyeglass and then to node-sass. This is a copy of plugin's options and so it can be modified or augmented.
    • compilationCallback - This callback accepts a css filename and options to use for compilation. This callback can be invoked 0 or more times. Each time it is invoked, the sass file will be compiled to the provided css file name (relative to the output directory) and the options provided.
  • verbose - When true, console logging will occur for each css file that is built along with timing information.

    In this way a sass file can be skipped or permuted during your build process by passing different options. Examples where this is useful include A/B testing or localization specific output. Note: if you invoke the callback more than once, you should change the output filename to avoid overwriting previous invocations' output.

Compilation Details

The compilation details object provides context about what is being compiled so that eyeglass and eyeglass integration code can make intelligent decisions about how to handle it.

  • srcPath: The directory to which the sassFilename is relative.
  • sassFilename: The path of the sass file being compiled (relative to srcPath).
  • fullSassFilename: The absolute path of the Sass file.
  • destDir: The directory where compiled css files are being written.
  • cssFilename: The CSS filename relative to the destDir.
  • fullCssFilename: The absolute path of the CSS file. (note: the file is not there yet, obviously)
  • options: The sassOptions as returned by the options generator (if provided).


Set the an environment variable DEBUG="broccoli-eyeglass:*" to get lots of debugging output that can help diagnose build issues -- especially issues with build caching and cache invalidation. You can also specifically use the following debug traits:

  • DEBUG="broccoli-eyeglass:persistent-cache" - Detailed logging for the cross-build persistent cache.
  • DEBUG="broccoli-eyeglass:hot-cache" - Detailed logging for the hot-cache that is used for rebuilds in the same broccoli process.

Eyeglass-specific debugging can by enabled by setting DEBUG="eyeglass:*"

You can debug with both of those set as well: DEBUG="broccoli-eyeglass,eyeglass:*"

For more details, see the documentation on debug.


This broccoli plugin uses two different caching layers to avoid unecessary builds of sass files.

Rebuild Caching

When the same broccoli-eyeglass instance is ran more than once, the rebuild is avoided by checking mtimes of dependencies to see if they have changed since the last build.

This is a very fast and highly accurate caching system that avoids rebuilds while running a single build instance (for things like ember serve) because mtime checks are pretty fast and only dependencies are stat'ed.

Unfortunately, this caching system only helps for rebuilds within the same instance as all the cache state is held in memory -- a first build is required every time.

Persistent Caching

Persistent Caching is more slightly expensive because it is content based (as opposed to mtimes) and because it has to check more things (npm modules might have been upgraded, etc), but it allows broccoli-eyeglass to skip the first build when nothing has changed, which is often the case between successive rebuilds.

Because it's more expensive, in some cases it may actually be slower than just building your stylesheets depending on the size/complexity of your Sass files. You should test with and without and verify a speedup before enabling this.

To enable persistent caching set the persistentCache option as described above.

Forcing Invalidation

The easiest way to force invalidate the rebuild cache is to just save the main sass file that needs to be rebuilt (see also: the unix touch command). There's not currently a way to disable the rebuild cache, we could add one, but we'd rather understand why it's not working first and try to address that.

To force an initial build and skip the persistent cache set the environment variable BROCCOLI_EYEGLASS=forceInvalidateCache.

General Cache Invalidation

The caches will only be invalidated correctly if this broccoli plugin knows what files are depended on and output. Sass files and eyeglass assets are already tracked. But other files migh be involved in your build, if that is the case,"dependency", absolutePath) must be called during the build. Similarly, if there are other files output during compilation, then you must call"additional-output", absolutePath).

Caching while developing eyeglass modules

When developing against an eyeglass module, it's common for the files in the module to change without a corresponding version change. If an eyeglass module is in development returning inDevelopment: true as an option from the eyeglass exports file will cause broccoli-eyeglass to more carefully check for invalidations in that module instead of just relying on semver.

Debugging the cache

As above, set DEBUG="broccoli-eyeglass" to see debug output that may help you report a bug or diagnose why caching isn't working like you thnk it should.


Do you like examples? You’re in luck!

  1. Read through a number of example project set-ups in

  2. Run those examples yourself by cding into an example underneath the examples folder.

Here’s a preview:

Example 1: The Simplest Possible Project

Consider the trivial project:

├── Brocfile.js
├── package.json
└── src
     ├── bar.scss
     ├── foo.scss
     └── _config.scss

With this Brocfile.js:

var BroccoliEyeglass = require('broccoli-eyeglass');

var options = {
  cssDir: 'css' /* This is the only required option */

var outputTree = new BroccoliEyeglass(['src'], options);

module.exports = outputTree;

You can build the project with the command

broccoli build dist

(after an npm install, of course).

With the default options, Broccoli-Eyeglass will discover all the Sass files that don’t start with an underscore, and compile them.

The result should be exactly this:

├── Brocfile.js
├── package.json
├── src
│    ├── bar.scss
│    ├── foo.scss
│    └── _config.scss
└── dist
    └── css
        ├── bar.css
        └── foo.css

More Examples

Go ahead and take a look at!