Configuration

Propshaft is configured in your Rails application via config.assets. These options are typically set in config/application.rb or environment-specific files like config/environments/development.rb.

Here are the available configuration options:

config.assets.paths

  • Description: An array of directories where Propshaft will look for assets. By default, Rails automatically adds app/assets, lib/assets, and vendor/assets from both the application and any gems/engines.
  • Type: Array of String or Pathname
  • Default: [] (populated by initializers)

config.assets.excluded_paths

  • Description: An array of directories to exclude from the load path. This is useful if a directory in config.assets.paths contains source files you don't want to be served directly, such as Sass partials.
  • Type: Array of String or Pathname
  • Default: []
  • Example: config.assets.excluded_paths << Rails.root.join("app/assets/stylesheets")

config.assets.version

  • Description: A string that is incorporated into the digest hash for all assets. Changing this value will cause all assets to be re-digested, effectively busting all caches.
  • Type: String
  • Default: "1"

config.assets.prefix

  • Description: The URL path where assets will be served from.
  • Type: String
  • Default: "/assets"

config.assets.output_path

  • Description: The file system path where precompiled assets will be written.
  • Type: Pathname
  • Default: Rails.root.join("public", config.assets.prefix) (e.g., public/assets)

config.assets.manifest_path

  • Description: The full path to the asset manifest file.
  • Type: Pathname
  • Default: config.assets.output_path.join(".manifest.json")

config.assets.compilers

  • Description: An array of compiler definitions. Each definition is a two-element array containing the MIME type and the compiler class.
  • Type: Array of [String, Class]
  • Default: 
    [
  [ "text/css",        Propshaft::Compiler::CssAssetUrls ],
  [ "text/css",        Propshaft::Compiler::SourceMappingUrls ],
  [ "text/javascript", Propshaft::Compiler::JsAssetUrls ],
  [ "text/javascript", Propshaft::Compiler::SourceMappingUrls ],
]

config.assets.integrity_hash_algorithm

  • Description: The cryptographic hash algorithm to use for Subresource Integrity (SRI). Set to nil or false to disable.
  • Type: String ("sha256", "sha384", "sha512") or nil
  • Default: nil

config.assets.quiet

  • Description: Suppress logger output for asset requests in development.
  • Type: Boolean
  • Default: false

config.assets.server

  • Description: A boolean indicating whether to mount the Propshaft development server middleware.
  • Type: Boolean
  • Default: Rails.env.development? || Rails.env.test?

Performance Tuning

For applications with a large number of assets, you can improve development-mode performance by using an evented file watcher. First, add the listen gem to your Gemfile:

group :development do
  gem "listen"
end

Then, configure Propshaft to use it in config/environments/development.rb:

config.file_watcher = ActiveSupport::EventedFileUpdateChecker