Add static assets support

.rubocop.yml

@@ -0,0 +1,124 @@
+AllCops:
+  TargetRubyVersion: 2.2
+  # RuboCop has a bunch of cops enabled by default. This setting tells RuboCop
+  # to ignore them, so only the ones explicitly set in this file are enabled.
+  DisabledByDefault: true
+  Exclude:
+    - 'lib/install/templates/**'
+    - 'vendor/**/*'
+    - 'node_modules/**/*'
+
+# Prefer &&/|| over and/or.
+Style/AndOr:
+  Enabled: true
+
+# Do not use braces for hash literals when they are the last argument of a
+# method call.
+Style/BracesAroundHashParameters:
+  Enabled: true
+
+# Align `when` with `case`.
+Style/CaseIndentation:
+  Enabled: true
+
+# Align comments with method definitions.
+Style/CommentIndentation:
+  Enabled: true
+
+# No extra empty lines.
+Style/EmptyLines:
+  Enabled: true
+
+# In a regular class definition, no empty lines around the body.
+Style/EmptyLinesAroundClassBody:
+  Enabled: true
+
+# In a regular method definition, no empty lines around the body.
+Style/EmptyLinesAroundMethodBody:
+  Enabled: true
+
+# In a regular module definition, no empty lines around the body.
+Style/EmptyLinesAroundModuleBody:
+  Enabled: true
+
+# Use Ruby >= 1.9 syntax for hashes. Prefer { a: :b } over { :a => :b }.
+Style/HashSyntax:
+  Enabled: true
+
+# Method definitions after `private` or `protected` isolated calls need one
+# extra level of indentation.
+Style/IndentationConsistency:
+  Enabled: true
+  EnforcedStyle: rails
+
+# Two spaces, no tabs (for indentation).
+Style/IndentationWidth:
+  Enabled: true
+
+Style/SpaceAfterColon:
+  Enabled: true
+
+Style/SpaceAfterComma:
+  Enabled: true
+
+Style/SpaceAroundEqualsInParameterDefault:
+  Enabled: true
+
+Style/SpaceAroundKeyword:
+  Enabled: true
+
+Style/SpaceAroundOperators:
+  Enabled: true
+
+Style/SpaceBeforeFirstArg:
+    Enabled: true
+
+# Defining a method with parameters needs parentheses.
+Style/MethodDefParentheses:
+  Enabled: true
+
+# Use `foo {}` not `foo{}`.
+Style/SpaceBeforeBlockBraces:
+  Enabled: true
+
+# Use `foo { bar }` not `foo {bar}`.
+Style/SpaceInsideBlockBraces:
+  Enabled: true
+
+# Use `{ a: 1 }` not `{a:1}`.
+Style/SpaceInsideHashLiteralBraces:
+  Enabled: true
+
+Style/SpaceInsideParens:
+  Enabled: true
+
+# Check quotes usage according to lint rule below.
+Style/StringLiterals:
+  Enabled: true
+  EnforcedStyle: double_quotes
+
+# Detect hard tabs, no hard tabs.
+Style/Tab:
+  Enabled: true
+
+# Blank lines should not have any spaces.
+Style/TrailingBlankLines:
+  Enabled: true
+
+# No trailing whitespace.
+Style/TrailingWhitespace:
+  Enabled: true
+
+# Use quotes for string literals when they are enough.
+Style/UnneededPercentQ:
+  Enabled: true
+
+# Align `end` with the matching keyword or starting expression except for
+# assignments, where it should be aligned with the LHS.
+Lint/EndAlignment:
+  Enabled: true
+  EnforcedStyleAlignWith: variable
+
+# Use my_method(my_arg) not my_method( my_arg ) or my_method my_arg.
+Lint/RequireParentheses:
+  Enabled: true

.travis.yml

@@ -13,10 +13,12 @@ cache:
   yarn: true
 
 install:
+  - gem install rubocop
   - nvm install node
   - node -v
   - npm i -g yarn
   - yarn
 
 script:
   - yarn lint
+  - rubocop

Gemfile

@@ -1,3 +1,3 @@
-source 'https://rubygems.org'
+source "https://rubygems.org"
 
 gemspec

README.md

@@ -15,14 +15,16 @@ Webpacker is currently compatible with Rails 4.2+, but there's no guarantee it w
 in the future.
 
 You can either make use of Webpacker during setup of a new application with `--webpack`
-or you can add the gem and run `bin/rails webpacker:install` in an existing application.
+or you can add the gem and run `./bin/rails webpacker:install` in an existing application.
 
 As the rubygems version isn't promised to be kept up to date until the release of Rails 5.1, you may want to include the gem directly from GitHub:
 
 ```ruby
 gem 'webpacker', github: 'rails/webpacker'
 ```
 
+You can also see a list of available commands by running `./bin/rails webpacker`
+
 ## Binstubs
 
 Webpacker ships with three binstubs: `./bin/webpack`, `./bin/webpack-watcher` and `./bin/webpack-dev-server`.
@@ -40,9 +42,7 @@ If you'd rather not have to run the two processes separately by hand, you can us
 
 Alternatively, you can run `./bin/webpack-dev-server`. This will launch a
 [Webpack Dev Server](https://webpack.github.io/docs/webpack-dev-server.html) listening on http://localhost:8080/
-serving your pack files. It will recompile your files as you make changes. You also need to set
-`config.x.webpacker[:dev_server_host]` in your `config/environments/development.rb` to tell Webpacker to load
-your packs from the Webpack Dev Server. This setup allows you to leverage advanced Webpack features, such
+serving your pack files. This setup allows you to leverage advanced Webpack features, such
 as [Hot Module Replacement](https://webpack.github.io/docs/hot-module-replacement-with-webpack.html).
 
 
@@ -59,11 +59,6 @@ as Webpack calls it).
 
 Let's say you're building a calendar. Your structure could look like this:
 
-```erb
-<%# app/views/layout/application.html.erb %>
-<%= javascript_pack_tag 'calendar' %>
-```
-
 ```js
 // app/javascript/packs/calendar.js
 require('calendar')
@@ -72,19 +67,108 @@ require('calendar')
 ```
 app/javascript/calendar/index.js // gets loaded by require('calendar')
 app/javascript/calendar/components/grid.jsx
+app/javascript/calendar/styles/grid.sass
 app/javascript/calendar/models/month.js
 ```
 
-But it could also look a million other ways. The only convention that Webpacker enforces is the
-one where entry points are automatically configured by the files in `app/javascript/packs`.
+```erb
+<%# app/views/layout/application.html.erb %>
+<%= javascript_pack_tag 'calendar' %>
+<%= stylesheet_pack_tag 'calendar' %>
+```
+
+But it could also look a million other ways.
+
+## Advanced Configuration
+
+By default, webpacker offers simple conventions for where the webpack configs, javascript app files and compiled webpack bundles will go in your rails app,
+but all these options are configurable from `config/webpack/paths.yml` file.
+
+```yml
+# config/webpack/paths.yml
+source: app/javascript
+entry: packs
+output: public
+config: config/webpack
+node_modules: node_modules
+```
+
+*Note:* Behind the scenes, webpacker will use same `entry` directory name inside `output`
+directory to emit bundles. For ex, `public/packs`
+
+Similary, you can also control and configure `webpack-dev-server` settings from
+`config/webpack/development.server.yml` file
+
+```yml
+# config/webpack/development.server.yml
+enabled: true
+host: localhost
+port: 8080
+```
+
+By default, `webpack-dev-server` uses `output` option specified in
+`paths.yml` as `contentBase`.
+
+**Note:** Don't forget to disable `webpack-dev-server` incase you are using
+`./bin/webpack-watcher` to serve assets in development mode otherwise
+you will get 404 for assets because the helper tag will use webpack-dev-server url
+to serve assets instead of public directory.
+
+## Linking to static assets
+
+Static assets like images, fonts and stylesheets support is enabled out-of-box so, you can link them into your javascript app code and have them compiled automatically.
+
+```js
+// React component example
+// app/javascripts/packs/hello_react.jsx
+import React from 'react'
+import ReactDOM from 'react-dom'
+import helloIcon from '../hello_react/images/icon.png'
+import './hello-react.sass'
+
+const Hello = props => (
+  <div className="hello-react">
+    <img src={helloIcon} alt="hello-icon" />
+    <p>Hello {props.name}!</p>
+  </div>
+)
+```
+
+under the hood webpack uses [extract-text-webpack-plugin](https://github.com/webpack-contrib/extract-text-webpack-plugin) plugin to extract all the referenced styles and compile it into a separate `[pack_name].css` bundle so that within your view you can use the `stylesheet_pack_tag` helper,
 
+```erb
+<%= stylesheet_pack_tag 'hello_react' %>
+```
+
+## Getting asset path
+
+Webpacker provides `asset_pack_path` helper to get the path of any given asset that's been compiled by webpack.
+
+**For ex,** if you want to create a `<link rel="prefetch">` or `<img />`
+for an asset used in your pack code you can reference them like this in your view,
+
+```erb
+<%= asset_pack_path 'hello_react.css' %>
+<% # => "/packs/hello_react.css" %>
+<img src="<%= asset_pack_path 'calendar.png' %>" />
+<% # => <img src="/packs/calendar.png" /> %>
+```
 
 ## Deployment
 
-To compile all the packs during deployment, you can use the `rails webpacker:compile` command. This
-will invoke the production configuration, which includes digesting. The `javascript_pack_tag` helper
-method will automatically insert the correct digest when run in production mode. Just like the asset
-pipeline does it.
+Webpacker hooks up a new `webpacker:compile` task to `assets:precompile`, which gets run whenever you run `assets:precompile`. The `javascript_pack_tag` and `stylesheet_pack_tag` helper method will automatically insert the correct HTML tag for compiled pack. Just like the asset pipeline does it. By default the output will look like this in different environments,
+
+```html
+  <!-- In development mode with webpack-dev-server -->
+  <script src="http://localhost:8080/calendar.js"></script>
+  <link rel="stylesheet" media="screen" href="http://localhost:8080/calendar.css">
+  <!-- In development mode -->
+  <script src="/packs/calendar.js"></script>
+  <link rel="stylesheet" media="screen" href="/packs/calendar.css">
+  <!-- In production mode -->
+  <script src="/packs/calendar-0bd141f6d9360cf4a7f5.js"></script>
+  <link rel="stylesheet" media="screen" href="/packs/calendar-dc02976b5f94b507e3b6.css">
+```
 
 ## Linking to sprockets assets
 
@@ -102,25 +186,42 @@ This is enabled by the `rails-erb-loader` loader rule in `config/webpack/shared.
 
 ## Ready for React
 
-To use Webpacker with React, just create a new app with `rails new myapp --webpack=react` (or run `rails webpacker:install:react` on a Rails 5.1 app already setup with webpack), and all the relevant dependencies
+To use Webpacker with React, just create a new app with `rails new myapp --webpack=react` (or run `rails webpacker:install:react` on a Rails app already setup with webpacker), and all the relevant dependencies
 will be added via yarn and changes to the configuration files made. Now you can create JSX files and
 have them properly compiled automatically.
 
 ## Ready for Angular with TypeScript
 
-To use Webpacker with Angular, just create a new app with `rails new myapp --webpack=angular` (or run `rails webpacker:install:angular` on a Rails 5.1 app already setup with webpack). TypeScript support and the Angular core libraries will be added via yarn and changes to the configuration files made. An example component written in TypeScript is also added to your project in `app/javascript` so that you can experiment Angular right away.
+To use Webpacker with Angular, just create a new app with `rails new myapp --webpack=angular` (or run `rails webpacker:install:angular` on a Rails app already setup with webpacker). TypeScript support and the Angular core libraries will be added via yarn and changes to the configuration files made. An example component written in TypeScript is also added to your project in `app/javascript` so that you can experiment Angular right away.
 
 ## Ready for Vue
 
-To use Webpacker with Vue, just create a new app with `rails new myapp --webpack=vue` (or run `rails webpacker:install:vue` on a Rails 5.1 app already setup with webpack). Vue and its supported libraries will be added via yarn and changes to the configuration files made. An example component is also added to your project in `app/javascript` so that you can experiment Vue right away.
+To use Webpacker with Vue, just create a new app with `rails new myapp --webpack=vue` (or run `rails webpacker:install:vue` on a Rails app already setup with webpacker). Vue and its supported libraries will be added via yarn and changes to the configuration files made. An example component is also added to your project in `app/javascript` so that you can experiment Vue right away.
+
+## Troubleshooting
+
+*  If you get this error `ENOENT: no such file or directory - node-sass` on Heroku
+or elsewhere during `assets:precompile` or `bundle exec rails webpacker:compile`
+then you would need to rebuild node-sass. It's a bit weird error,
+basically, it can't find the `node-sass` binary.
+An easy solution is to create a postinstall hook - `npm rebuild node-sass` in
+`package.json` and that will ensure `node-sass` is rebuild whenever
+you install any new modules.
 
+* If you get this error `Can't find hello_react.js in manifest.json`
+when loading a view in browser it's because Webpack is still compiling packs.
+Webpacker uses a `manifest.json` file to keep track of packs in all environments,
+however since this file is generated after packs are compiled by webpack. So,
+if you load a view in browser whilst webpack is compiling you will get this error.
+Therefore, make sure webpack
+(i.e `.bin/webpack-watcher` or `.bin/webpack-dev-sever`) is running and has
+completed the compilation successfully before loading a view.
 
 ## Wishlist
 
 - Improve process for linking to assets compiled by sprockets - shouldn't need to specify
 ` <% helpers = ActionController::Base.helpers %>` at the beginning of each file
 - Consider chunking setup
-- Consider on-demand compiling with digests when digesting=true
 
 ## License
 Webpacker is released under the [MIT License](https://opensource.org/licenses/MIT).

lib/install/bin/webpack-dev-server.tt

@@ -1,27 +1,33 @@
 <%= shebang %>
-require 'shellwords'
+$stdout.sync = true
 
-ENV['RAILS_ENV'] ||= 'development'
-RAILS_ENV   = ENV['RAILS_ENV']
+require "shellwords"
+require "yaml"
 
-ENV['NODE_ENV'] ||= RAILS_ENV
-NODE_ENV    = ENV['NODE_ENV']
+ENV["RAILS_ENV"] ||= "development"
+RAILS_ENV = ENV["RAILS_ENV"]
 
-APP_PATH = File.expand_path('../', __dir__)
-ESCAPED_APP_PATH = APP_PATH.shellescape
+ENV["NODE_ENV"] ||= RAILS_ENV
+NODE_ENV = ENV["NODE_ENV"]
 
-SET_NODE_PATH  = "NODE_PATH=#{ESCAPED_APP_PATH}/node_modules"
-WEBPACKER_BIN  = "./node_modules/.bin/webpack-dev-server"
-WEBPACK_CONFIG = "#{ESCAPED_APP_PATH}/config/webpack/#{NODE_ENV}.js"
+APP_PATH    = File.expand_path("../", __dir__)
+CONFIG_PATH = File.join(APP_PATH, "config/webpack/paths.yml")
 
-# Warn the user if the configuration is not set
-RAILS_ENV_CONFIG = File.join("config", "environments", "#{RAILS_ENV}.rb")
+begin
+  paths = YAML.load(File.read(CONFIG_PATH))
 
-# Look into the environment file for a non-commented variable declaration
-unless File.foreach(File.join(APP_PATH, RAILS_ENV_CONFIG)).detect { |line| line.match(/^\s*[^#]*config\.x\.webpacker\[\:dev_server_host\].*=/) }
-  puts "Warning: if you want to use webpack-dev-server, you need to tell Webpacker to serve asset packs from it. Please set config.x.webpacker[:dev_server_host] in #{RAILS_ENV_CONFIG}.\n\n"
+  NODE_MODULES_PATH   = File.join(APP_PATH.shellescape, paths["node_modules"])
+  WEBPACK_CONFIG_PATH = File.join(APP_PATH.shellescape, paths["config"])
+
+  WEBPACK_BIN       = "#{NODE_MODULES_PATH}/.bin/webpack-dev-server"
+  DEV_SERVER_CONFIG = "#{WEBPACK_CONFIG_PATH}/development.server.js"
+rescue Errno::ENOENT, NoMethodError
+  puts "Configuration not found in config/webpacker/paths.yml."
+  puts "Please run bundle exec rails webpacker:install to install webpacker"
+  exit!
 end
 
 Dir.chdir(APP_PATH) do
-  exec "#{SET_NODE_PATH} #{WEBPACKER_BIN} --config #{WEBPACK_CONFIG} --content-base #{ESCAPED_APP_PATH}/public/packs #{ARGV.join(" ")}"
+  exec "NODE_PATH=#{NODE_MODULES_PATH} #{WEBPACK_BIN} --progress --color " \
+    "--config #{DEV_SERVER_CONFIG}"
 end