The Rails asset pipeline makes a number of assumptions about what's best for deploying JavaScript, including asset digest fingerprints and long-lived cache headers - mostly to increase "cacheability". Rails also assumes a single parent directory, /public/assets, to make it easier to look up the file path for a given asset.

We want Sprockets to compile service worker JavaScript from ES6/7, CoffeeScript, ERB, etc. but must remove the caching and scoping mechanisms offered by Rails asset pipeline defaults. This is where serviceworker-rails comes in.

Check out the blog post for more background.