Rake::Pipeline is a system for packaging assets for deployment to the web. It uses Rake under the hood for dependency management and updating output files based on input changes.
The easiest way to use Rake::Pipeline is via an Assetfile file in the root of your project.
A sample Assetfile looks like this:
Each input block defines a collection of files, and a pipeline that transforms those files. Within each pipeline, you can specify a series of filters to describe the transformations you'd like to apply to the files.
Upgrading from Previous Versions
The Assetfile syntax has changed in version 0.6.0. In previous versions, each Assetfile defined a single pipeline, and input statements would add input files to that pipeline. After version 0.6.0, multiple pipelines can be defined in an Assetfile. The input method now takes a block, and this block defines a pipeline. This means that any match blocks or filters must be defined inside an input block, and no longer at the top level. For example, this:
# Prior to 0.6.0 output "public" input "assets" match "**/*.js" do concat end
would now be written as:
# After 0.6.0 output "public" input "assets" do match "**/*.js" do concat end end
A filter is a simple class that inherits from. A filter must implement a single method, called generate_output, which takes two parameters: a list of input files and the output file.
Both the input and output files areobjects. The most important methods on a are:
: the path of the file, relative to its input root
: read the contents of the file
: write a String to the file
For example, a simple concatenation filter would look like:
class ConcatFilter < Rake::Pipeline::Filter def generate_output(inputs, output) inputs.each do |input| output.write input.read end end end
If you had a series of input files like:
and you specified the ConcatFilter in your Assetfile like:
filter ConcatFilter, "application.js"
The filter would receive a single call to generate_output with an Array ofs representing each of the three files, and a representing application.js.
If your filter is operating on binary data, like images, rather than textual data, like source code, you can specify that in your filter:
class ConcatFilter < Rake::Pipeline::Filter processes_binary_files def generate_output(inputs, output) inputs.each do |input| output.write input.read end end end
This will stop `Rake::Pipeline` from trying to interpret the input files as `UTF-8`, which obviously will not work on binary data.
Rake::Pipeline comes with a built-in filter, github.com/wycats/rake-pipeline-web-filters).. Its implementation is the same as the ConcatFilter above. Other filters that are useful for web development like a CoffeeScriptFilter and SassFilter are available in [rake-pipeline-web-filters](
To start up the preview server, run rakep server. This will start up a server that automatically recompiles files for you on the fly and serves up the files you need.
This should allow you to have a single index.html file pointing at the same files in both development and production.
To compile all assets before deployment, simply run:
$ rakep build
If a filter does not specify that it processes binary files, Rake::Pipeline will open all inputs and outputs as UTF-8.
This means that if you have files encoded in other encodings, like Latin-1, Rake::Pipeline will raise an exception. In this situation, you need to open the offending file in your text editor and re-save it as UTF-8.
Public Release Requirement
Before publicly releasing this code, we need to properly support encodings other than UTF-8. That means using the default_external instead of hardcoding to UTF-8 and providing a mechanism for specifying the encoding of a file using a magic comment.