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Diffstat (limited to 'guides/source/asset_pipeline.md')
| -rw-r--r-- | guides/source/asset_pipeline.md | 172 |
1 files changed, 79 insertions, 93 deletions
diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md index 93acebf000..e6d5aed135 100644 --- a/guides/source/asset_pipeline.md +++ b/guides/source/asset_pipeline.md @@ -35,7 +35,7 @@ rails new appname --skip-sprockets ``` Rails automatically adds the `sass-rails`, `coffee-rails` and `uglifier` -gems to your Gemfile, which are used by Sprockets for asset compression: +gems to your `Gemfile`, which are used by Sprockets for asset compression: ```ruby gem 'sass-rails' @@ -44,8 +44,8 @@ gem 'coffee-rails' ``` Using the `--skip-sprockets` option will prevent Rails from adding -them to your Gemfile, so if you later want to enable -the asset pipeline you will have to add those gems to your Gemfile. Also, +them to your `Gemfile`, so if you later want to enable +the asset pipeline you will have to add those gems to your `Gemfile`. Also, creating an application with the `--skip-sprockets` option will generate a slightly different `config/application.rb` file, with a require statement for the sprockets railtie that is commented-out. You will have to remove @@ -65,7 +65,7 @@ config.assets.js_compressor = :uglifier ``` NOTE: The `sass-rails` gem is automatically used for CSS compression if included -in the Gemfile and no `config.assets.css_compressor` option is set. +in the `Gemfile` and no `config.assets.css_compressor` option is set. ### Main Features @@ -78,9 +78,9 @@ requests can mean faster loading for your application. Sprockets concatenates all JavaScript files into one master `.js` file and all CSS files into one master `.css` file. As you'll learn later in this guide, you can customize this strategy to group files any way you like. In production, -Rails inserts an MD5 fingerprint into each filename so that the file is cached -by the web browser. You can invalidate the cache by altering this fingerprint, -which happens automatically whenever you change the file contents. +Rails inserts an SHA256 fingerprint into each filename so that the file is +cached by the web browser. You can invalidate the cache by altering this +fingerprint, which happens automatically whenever you change the file contents. The second feature of the asset pipeline is asset minification or compression. For CSS files, this is done by removing whitespace and comments. For JavaScript, @@ -106,7 +106,7 @@ or in web browsers) to keep their own copy of the content. When the content is updated, the fingerprint will change. This will cause the remote clients to request a new copy of the content. This is generally known as _cache busting_. -The technique sprockets uses for fingerprinting is to insert a hash of the +The technique Sprockets uses for fingerprinting is to insert a hash of the content into the name, usually at the end. For example a CSS file `global.css` ``` @@ -154,7 +154,7 @@ environments. You can enable or disable it in your configuration through the More reading: -* [Optimize caching](http://code.google.com/speed/page-speed/docs/caching.html) +* [Optimize caching](https://developers.google.com/speed/docs/insights/LeverageBrowserCaching) * [Revving Filenames: don't use querystring](http://www.stevesouders.com/blog/2008/08/23/revving-filenames-dont-use-querystring/) @@ -181,7 +181,7 @@ When you generate a scaffold or a controller, Rails also generates a JavaScript file (or CoffeeScript file if the `coffee-rails` gem is in the `Gemfile`) and a Cascading Style Sheet file (or SCSS file if `sass-rails` is in the `Gemfile`) for that controller. Additionally, when generating a scaffold, Rails generates -the file scaffolds.css (or scaffolds.scss if `sass-rails` is in the +the file `scaffolds.css` (or `scaffolds.scss` if `sass-rails` is in the `Gemfile`.) For example, if you generate a `ProjectsController`, Rails will also add a new @@ -202,12 +202,12 @@ will result in your assets being included more than once. WARNING: When using asset precompilation, you will need to ensure that your controller assets will be precompiled when loading them on a per page basis. By -default .coffee and .scss files will not be precompiled on their own. See +default `.coffee` and `.scss` files will not be precompiled on their own. See [Precompiling Assets](#precompiling-assets) for more information on how precompiling works. NOTE: You must have an ExecJS supported runtime in order to use CoffeeScript. -If you are using Mac OS X or Windows, you have a JavaScript runtime installed in +If you are using macOS or Windows, you have a JavaScript runtime installed in your operating system. Check [ExecJS](https://github.com/rails/execjs#readme) documentation to know all supported JavaScript runtimes. You can also disable generation of controller specific asset files by adding the @@ -283,10 +283,10 @@ You can view the search path by inspecting `Rails.application.config.assets.paths` in the Rails console. Besides the standard `assets/*` paths, additional (fully qualified) paths can be -added to the pipeline in `config/application.rb`. For example: +added to the pipeline in `config/initializers/assets.rb`. For example: ```ruby -config.assets.paths << Rails.root.join("lib", "videoplayer", "flash") +Rails.application.config.assets.paths << Rails.root.join("lib", "videoplayer", "flash") ``` Paths are traversed in the order they occur in the search path. By default, @@ -335,7 +335,7 @@ an asset has been updated and if so loads it into the page: <%= javascript_include_tag "application", "data-turbolinks-track" => "reload" %> ``` -In regular views you can access images in the `public/assets/images` directory +In regular views you can access images in the `app/assets/images` directory like this: ```erb @@ -346,9 +346,9 @@ Provided that the pipeline is enabled within your application (and not disabled in the current environment context), this file is served by Sprockets. If a file exists at `public/assets/rails.png` it is served by the web server. -Alternatively, a request for a file with an MD5 hash such as -`public/assets/rails-af27b6a414e6da00003503148be9b409.png` is treated the same -way. How these hashes are generated is covered in the [In +Alternatively, a request for a file with an SHA256 hash such as +`public/assets/rails-f90d8a84c707a8dc923fca1ca1895ae8ed0a09237f6992015fef1e11be77c023.png` +is treated the same way. How these hashes are generated is covered in the [In Production](#in-production) section later on in this guide. Sprockets will also look through the paths specified in `config.assets.paths`, @@ -383,7 +383,7 @@ it would make sense to have an image in one of the asset load paths, such as already available in `public/assets` as a fingerprinted file, then that path is referenced. -If you want to use a [data URI](http://en.wikipedia.org/wiki/Data_URI_scheme) - +If you want to use a [data URI](https://en.wikipedia.org/wiki/Data_URI_scheme) - a method of embedding the image data directly into the CSS file - you can use the `asset_data_uri` helper. @@ -435,11 +435,11 @@ Sprockets uses manifest files to determine which assets to include and serve. These manifest files contain _directives_ - instructions that tell Sprockets which files to require in order to build a single CSS or JavaScript file. With these directives, Sprockets loads the files specified, processes them if -necessary, concatenates them into one single file and then compresses them (if -`Rails.application.config.assets.compress` is true). By serving one file rather -than many, the load time of pages can be greatly reduced because the browser -makes fewer requests. Compression also reduces file size, enabling the -browser to download them faster. +necessary, concatenates them into one single file and then compresses them +(based on value of `Rails.application.config.assets.js_compressor`). By serving +one file rather than many, the load time of pages can be greatly reduced because +the browser makes fewer requests. Compression also reduces file size, enabling +the browser to download them faster. For example, a new Rails application includes a default @@ -447,15 +447,15 @@ For example, a new Rails application includes a default ```js // ... -//= require jquery -//= require jquery_ujs +//= require rails-ujs +//= require turbolinks //= require_tree . ``` In JavaScript files, Sprockets directives begin with `//=`. In the above case, the file is using the `require` and the `require_tree` directives. The `require` directive is used to tell Sprockets the files you wish to require. Here, you are -requiring the files `jquery.js` and `jquery_ujs.js` that are available somewhere +requiring the files `rails-ujs.js` and `turbolinks.js` that are available somewhere in the search path for Sprockets. You need not supply the extensions explicitly. Sprockets assumes you are requiring a `.js` file when done from within a `.js` file. @@ -485,7 +485,7 @@ which contains these lines: Rails creates both `app/assets/javascripts/application.js` and `app/assets/stylesheets/application.css` regardless of whether the ---skip-sprockets option is used when creating a new rails application. This is +--skip-sprockets option is used when creating a new Rails application. This is so you can easily add asset pipelining later if you like. The directives that work in JavaScript files also work in stylesheets @@ -572,19 +572,18 @@ would generate this HTML: The `body` param is required by Sprockets. -### Runtime Error Checking +### Raise an Error When an Asset is Not Found -By default the asset pipeline will check for potential errors in development mode during -runtime. To disable this behavior you can set: +If you are using sprockets-rails >= 3.2.0 you can configure what happens +when an asset lookup is performed and nothing is found. If you turn off "asset fallback" +then an error will be raised when an asset cannot be found. ```ruby -config.assets.raise_runtime_errors = false +config.assets.unknown_asset_fallback = false ``` -When this option is true, the asset pipeline will check if all the assets loaded -in your application are included in the `config.assets.precompile` list. -If `config.assets.digest` is also true, the asset pipeline will require that -all requests for assets include digests. +If "asset fallback" is enabled then when an asset cannot be found the path will be +output instead and no error raised. The asset fallback behavior is enabled by default. ### Turning Digests Off @@ -641,7 +640,7 @@ In the production environment Sprockets uses the fingerprinting scheme outlined above. By default Rails assumes assets have been precompiled and will be served as static assets by your web server. -During the precompilation phase an MD5 is generated from the contents of the +During the precompilation phase an SHA256 is generated from the contents of the compiled files, and inserted into the filenames as they are written to disk. These fingerprinted names are used by the Rails helpers in place of the manifest name. @@ -724,28 +723,30 @@ If you have other manifests or individual stylesheets and JavaScript files to include, you can add them to the `precompile` array in `config/initializers/assets.rb`: ```ruby -Rails.application.config.assets.precompile += ['admin.js', 'admin.css', 'swfObject.js'] +Rails.application.config.assets.precompile += %w( admin.js admin.css ) ``` -NOTE. Always specify an expected compiled filename that ends with .js or .css, +NOTE. Always specify an expected compiled filename that ends with `.js` or `.css`, even if you want to add Sass or CoffeeScript files to the precompile array. -The task also generates a `manifest-md5hash.json` that contains a list with -all your assets and their respective fingerprints. This is used by the Rails -helper methods to avoid handing the mapping requests back to Sprockets. A -typical manifest file looks like: +The task also generates a `.sprockets-manifest-md5hash.json` (where `md5hash` is +an MD5 hash) that contains a list with all your assets and their respective +fingerprints. This is used by the Rails helper methods to avoid handing the +mapping requests back to Sprockets. A typical manifest file looks like: ```ruby -{"files":{"application-723d1be6cc741a3aabb1cec24276d681.js":{"logical_path":"application.js","mtime":"2013-07-26T22:55:03-07:00","size":302506, -"digest":"723d1be6cc741a3aabb1cec24276d681"},"application-12b3c7dd74d2e9df37e7cbb1efa76a6d.css":{"logical_path":"application.css","mtime":"2013-07-26T22:54:54-07:00","size":1560, -"digest":"12b3c7dd74d2e9df37e7cbb1efa76a6d"},"application-1c5752789588ac18d7e1a50b1f0fd4c2.css":{"logical_path":"application.css","mtime":"2013-07-26T22:56:17-07:00","size":1591, -"digest":"1c5752789588ac18d7e1a50b1f0fd4c2"},"favicon-a9c641bf2b81f0476e876f7c5e375969.ico":{"logical_path":"favicon.ico","mtime":"2013-07-26T23:00:10-07:00","size":1406, -"digest":"a9c641bf2b81f0476e876f7c5e375969"},"my_image-231a680f23887d9dd70710ea5efd3c62.png":{"logical_path":"my_image.png","mtime":"2013-07-26T23:00:27-07:00","size":6646, -"digest":"231a680f23887d9dd70710ea5efd3c62"}},"assets":{"application.js": -"application-723d1be6cc741a3aabb1cec24276d681.js","application.css": -"application-1c5752789588ac18d7e1a50b1f0fd4c2.css", -"favicon.ico":"favicona9c641bf2b81f0476e876f7c5e375969.ico","my_image.png": -"my_image-231a680f23887d9dd70710ea5efd3c62.png"}} +{"files":{"application-aee4be71f1288037ae78b997df388332edfd246471b533dcedaa8f9fe156442b.js":{"logical_path":"application.js","mtime":"2016-12-23T20:12:03-05:00","size":412383, +"digest":"aee4be71f1288037ae78b997df388332edfd246471b533dcedaa8f9fe156442b","integrity":"sha256-ruS+cfEogDeueLmX3ziDMu39JGRxtTPc7aqPn+FWRCs="}, +"application-86a292b5070793c37e2c0e5f39f73bb387644eaeada7f96e6fc040a028b16c18.css":{"logical_path":"application.css","mtime":"2016-12-23T19:12:20-05:00","size":2994, +"digest":"86a292b5070793c37e2c0e5f39f73bb387644eaeada7f96e6fc040a028b16c18","integrity":"sha256-hqKStQcHk8N+LA5fOfc7s4dkTq6tp/lub8BAoCixbBg="}, +"favicon-8d2387b8d4d32cecd93fa3900df0e9ff89d01aacd84f50e780c17c9f6b3d0eda.ico":{"logical_path":"favicon.ico","mtime":"2016-12-23T20:11:00-05:00","size":8629, +"digest":"8d2387b8d4d32cecd93fa3900df0e9ff89d01aacd84f50e780c17c9f6b3d0eda","integrity":"sha256-jSOHuNTTLOzZP6OQDfDp/4nQGqzYT1DngMF8n2s9Dto="}, +"my_image-f4028156fd7eca03584d5f2fc0470df1e0dbc7369eaae638b2ff033f988ec493.png":{"logical_path":"my_image.png","mtime":"2016-12-23T20:10:54-05:00","size":23414, +"digest":"f4028156fd7eca03584d5f2fc0470df1e0dbc7369eaae638b2ff033f988ec493","integrity":"sha256-9AKBVv1+ygNYTV8vwEcN8eDbxzaequY4sv8DP5iOxJM="}}, +"assets":{"application.js":"application-aee4be71f1288037ae78b997df388332edfd246471b533dcedaa8f9fe156442b.js", +"application.css":"application-86a292b5070793c37e2c0e5f39f73bb387644eaeada7f96e6fc040a028b16c18.css", +"favicon.ico":"favicon-8d2387b8d4d32cecd93fa3900df0e9ff89d01aacd84f50e780c17c9f6b3d0eda.ico", +"my_image.png":"my_image-f4028156fd7eca03584d5f2fc0470df1e0dbc7369eaae638b2ff033f988ec493.png"}} ``` The default location for the manifest is the root of the location specified in @@ -837,7 +838,7 @@ config.assets.compile = true On the first request the assets are compiled and cached as outlined in development above, and the manifest names used in the helpers are altered to -include the MD5 hash. +include the SHA256 hash. Sprockets also sets the `Cache-Control` HTTP header to `max-age=31536000`. This signals all caches between your server and the client browser that this content @@ -849,18 +850,18 @@ This mode uses more memory, performs more poorly than the default and is not recommended. If you are deploying a production application to a system without any -pre-existing JavaScript runtimes, you may want to add one to your Gemfile: +pre-existing JavaScript runtimes, you may want to add one to your `Gemfile`: ```ruby group :production do - gem 'therubyracer' + gem 'mini_racer' end ``` ### CDNs CDN stands for [Content Delivery -Network](http://en.wikipedia.org/wiki/Content_delivery_network), they are +Network](https://en.wikipedia.org/wiki/Content_delivery_network), they are primarily designed to cache assets all over the world so that when a browser requests the asset, a cached copy will be geographically close to that browser. If you are serving assets directly from your Rails server in production, the @@ -908,7 +909,7 @@ domain, you do not need to specify a protocol or "scheme" such as `http://` or that is generated will match how the webpage is accessed by default. You can also set this value through an [environment -variable](http://en.wikipedia.org/wiki/Environment_variable) to make running a +variable](https://en.wikipedia.org/wiki/Environment_variable) to make running a staging copy of your site easier: ``` @@ -1024,7 +1025,7 @@ to tell our CDN (and browser) that the asset is "public", that means any cache can store the request. Also we commonly want to set `max-age` which is how long the cache will store the object before invalidating the cache. The `max-age` value is set to seconds with a maximum possible value of `31536000` which is one -year. You can do this in your rails application by setting +year. You can do this in your Rails application by setting ``` config.public_file_server.headers = { @@ -1068,7 +1069,7 @@ Customizing the Pipeline ### CSS Compression One of the options for compressing CSS is YUI. The [YUI CSS -compressor](http://yui.github.io/yuicompressor/css.html) provides +compressor](https://yui.github.io/yuicompressor/css.html) provides minification. The following line enables YUI compression, and requires the `yui-compressor` @@ -1089,7 +1090,7 @@ Possible options for JavaScript compression are `:closure`, `:uglifier` and `:yui`. These require the use of the `closure-compiler`, `uglifier` or `yui-compressor` gems, respectively. -The default Gemfile includes [uglifier](https://github.com/lautis/uglifier). +The default `Gemfile` includes [uglifier](https://github.com/lautis/uglifier). This gem wraps [UglifyJS](https://github.com/mishoo/UglifyJS) (written for NodeJS) in Ruby. It compresses your code by removing white space and comments, shortening local variable names, and performing other micro-optimizations such @@ -1102,21 +1103,16 @@ config.assets.js_compressor = :uglifier ``` NOTE: You will need an [ExecJS](https://github.com/rails/execjs#readme) -supported runtime in order to use `uglifier`. If you are using Mac OS X or +supported runtime in order to use `uglifier`. If you are using macOS or Windows you have a JavaScript runtime installed in your operating system. -NOTE: The `config.assets.compress` initialization option is no longer used in -Rails to enable either CSS or JavaScript compression. Setting it will have no -effect on the application. Instead, setting `config.assets.css_compressor` and -`config.assets.js_compressor` will control compression of CSS and JavaScript -assets. ### Serving GZipped version of assets -By default, gzipped version of compiled assets will be generated, along -with the non-gzipped version of assets. Gzipped assets help reduce the transmission of -data over the wire. You can configure this by setting the `gzip` flag. +By default, gzipped version of compiled assets will be generated, along with +the non-gzipped version of assets. Gzipped assets help reduce the transmission +of data over the wire. You can configure this by setting the `gzip` flag. ```ruby config.assets.gzip = false # disable gzipped assets generation @@ -1219,35 +1215,25 @@ Sprockets. Making Your Library or Gem a Pre-Processor ------------------------------------------ -As Sprockets uses [Tilt](https://github.com/rtomayko/tilt) as a generic -interface to different templating engines, your gem should just implement the -Tilt template protocol. Normally, you would subclass `Tilt::Template` and -reimplement the `prepare` method, which initializes your template, and the -`evaluate` method, which returns the processed source. The original source is -stored in `data`. Have a look at -[`Tilt::Template`](https://github.com/rtomayko/tilt/blob/master/lib/tilt/template.rb) -sources to learn more. +Sprockets uses Processors, Transformers, Compressors, and Exporters to extend +Sprockets functionality. Have a look at +[Extending Sprockets](https://github.com/rails/sprockets/blob/master/guides/extending_sprockets.md) +to learn more. Here we registered a preprocessor to add a comment to the end +of text/css (`.css`) files. ```ruby -module BangBang - class Template < ::Tilt::Template - def prepare - # Do any initialization here - end - - # Adds a "!" to original template. - def evaluate(scope, locals, &block) - "#{data}!" - end +module AddComment + def self.call(input) + { data: input[:data] + "/* Hello From my sprockets extension */" } end end ``` -Now that you have a `Template` class, it's time to associate it with an -extension for template files: +Now that you have a module that modifies the input data, it's time to register +it as a preprocessor for your mime type. ```ruby -Sprockets.register_engine '.bang', BangBang::Template +Sprockets.register_preprocessor 'text/css', AddComment ``` Upgrading from Old Versions of Rails @@ -1291,12 +1277,12 @@ config.assets.js_compressor = :uglifier # Don't fallback to assets pipeline if a precompiled asset is missed config.assets.compile = false -# Generate digests for assets URLs. This is planned for deprecation. +# Generate digests for assets URLs. config.assets.digest = true # Precompile additional assets (application.js, application.css, and all # non-JS/CSS are already added) -# config.assets.precompile += %w( search.js ) +# config.assets.precompile += %w( admin.js admin.css ) ``` Rails 4 and above no longer set default config values for Sprockets in `test.rb`, so |