title: Webpack plugin for rails assets compatible manifest
body: <p>I'm trying to fully replace the rails asset pipeline with a webpack based pipeline. I've got the dev setup with the <code>webpack-dev-server</code> and hot reloading etc all working beautifully. Now what I'm trying to achieve is a compilation step for production that would mimic how rails compiles assets (digesting / generating a compatible manifest.json file) such that I can still use helpers like <code>javascript_include_tag</code> etc. This is where I'm stuck.</p>
  
  <p>I've read lots of tutorials on using webpack with rails, but they all end up writing their own view helpers to load the assets. I'm trying to avoid this because I don't want extra overhead or for devs to need to understand a different pipeline. I also want config like <code>asset_host=</code> to work out of the box for using a CDN etc.</p>
  
  <p>Ultimately, what I want is something similar to <a href="https://www.npmjs.com/package/gulp-rev-rails-manifest" rel="nofollow">gulp-rev-rails-manifest</a> that generates a rails-asset-pipeline compatible manifest file on compilation, but I haven't found a plugin (yet) that exists for Webpack. So...</p>
  
  <ol>
  <li>is it possible to run a webpack build through a gulp stream <em>using webpack only</em> (ie not using gulp-webpack) so I can use the above gulp plugin. The reason I don't want to use gulp-webpack is that it takes over your entries / output etc and I find that whole setup confusing since this all already exists in <code>webpack.config</code></li>
  </ol>
  
  <p>Or </p>
  
  <ol start="2">
  <li>Does anyone have any decent resources on writing plugins for Webpack. It seems a bit of a black box to me and the official site has a menu section for "How to write a plugin" but it's not actually a link to anything.</li>
  </ol>
  
  <p>Or</p>
  
  <ol start="3">
  <li>Is there actually a plugin that will do exactly this and I don't know how to search properly on the interwebs.</li>
  </ol>
  
  <p>Any help is greatly appreciated :)</p>