Class: Butler::Static

Inherits:
Object
  • Object
show all
Defined in:
lib/butler/static.rb

Overview

Butler::Static

is a Static Web Server based on ActionDispatch::Static. It is intended to be used with Rails in an environment where serving static assets through a specialized web server such as nginx is technically not an option.

Butler::Static extends ActionDispatch::Static’s func- tionality to allow a the developer to set custom rules for the HTTP headers that the files sent should carry.

The author’s intent was to allow Rails to serve static assets with custom HTTP Headers. This allows for example serving webfonts or icon fonts carrying the appropriate HTTP headers via a Content Delivery Network (CDN) such as Amazon’s Cloudfront. Files requested by the CDN will need to carry the headers the file should be sent with to the visitor’s browser already when being sent from the web server.

ActionDispatch::Static, Rack::Static et al. don’t allow (yet) to add custom HTTP headers to files because the underlying Rack::File implementation only allows for setting a static ‘Cache-Control’ header.

Code adapted from Rails’ ActionDispatch::Static.

If no matching file can be found in the precompiled assets the request will bubble up to the Rails stack to decide how to handle it

Usage with Rails:

# config/environment/production.rb
config.middleware.delete ActionDispatch::Static
config.middleware.insert_before Rack::Cache, Butler::Static

# Provide the header rules like so
config.assets.header_rules = {
  rule         => { header_field => content },
  another_rule => { header_field => content }
}

# These rules are shipped along
# 1) Global
:global => Matches every file

# 2) Folders
'/folder' => Matches all files in a certain folder
'/folder/subfolder' => ...
  Note: Provide the folder as a string,
        with or without the starting slash

# 3) File Extensions
['css', 'js'] => Will match all files ending in .css or .js
%w(css js) => ...
  Note: Provide the file extensions in an array,
        use any ruby syntax you like to set that array up

# 4) Regular Expressions / Regexp
%r{\.(?:css|js)\z} => will match all files ending in .css or .js
/\.(?:eot|ttf|otf|woff|svg)\z/ => will match all files ending
   in the most common web font formats

# 5) Shortcuts
There is currently only one shortcut defined.
:fonts => will match all files ending in eot, ttf, otf, woff, svg
   using the Regexp stated above

Note: The rules will be applied in the order the are listed,
      thus more special rules further down below can override
      general global HTTP header settings

Instance Method Summary collapse

Constructor Details

#initialize(app, path, options = {}) ⇒ Static

Returns a new instance of Static.



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# File 'lib/butler/static.rb', line 79

def initialize(app, path, options={})
  @app = app # Rails app
  config = {}
  # Rules for setting HTTP Headers on files
  config[:header_rules] = options[:header_rules] if options[:header_rules]
  @file_handler = Butler::Handler.new(path, config)
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/butler/static.rb', line 87

def call(env)
  case env['REQUEST_METHOD']
  when 'GET', 'HEAD'
    path = env['PATH_INFO'].chomp('/')
    if match = @file_handler.match?(path)
      env['PATH_INFO'] = match
      return @file_handler.call(env)
    end
  end

  @app.call(env)
end