Add support to override manifest_path as a configuration

lib/propshaft/assembly.rb

@@ -19,8 +19,8 @@ def load_path
   end
 
   def resolver
-    @resolver ||= if manifest_path.exist?
-      Propshaft::Resolver::Static.new manifest_path: manifest_path, prefix: config.prefix
+    @resolver ||= if config.manifest_path.exist?
+      Propshaft::Resolver::Static.new manifest_path: config.manifest_path.manifest_path, prefix: config.prefix
     else
       Propshaft::Resolver::Dynamic.new load_path: load_path, prefix: config.prefix
     end
@@ -32,7 +32,7 @@ def server
 
   def processor
     Propshaft::Processor.new \
-      load_path: load_path, output_path: config.output_path, compilers: compilers
+      load_path: load_path, output_path: config.output_path, compilers: compilers, manifest_path: config.manifest_path.manifest_path
   end
 
   def compilers
@@ -51,9 +51,4 @@ def reveal(path_type = :logical_path)
       asset.send(path_type)
     end
   end
-
-  private
-    def manifest_path
-      config.output_path.join(Propshaft::Processor::MANIFEST_FILENAME)
-    end
 end

lib/propshaft/processor.rb

@@ -1,12 +1,11 @@
 require "propshaft/output_path"
 
 class Propshaft::Processor
-  MANIFEST_FILENAME = ".manifest.json"
+  attr_reader :load_path, :output_path, :compilers, :manifest_path
 
-  attr_reader :load_path, :output_path, :compilers
-
-  def initialize(load_path:, output_path:, compilers:)
+  def initialize(load_path:, output_path:, compilers:, manifest_path:)
     @load_path, @output_path = load_path, output_path
+    @manifest_path = manifest_path
     @compilers = compilers
   end
 
@@ -31,7 +30,8 @@ def ensure_output_path_exists
 
 
     def write_manifest
-      File.open(output_path.join(MANIFEST_FILENAME), "wb+") do |manifest|
+      FileUtils.mkdir_p(File.dirname(manifest_path))
+      File.open(manifest_path, "wb+") do |manifest|
         manifest.write load_path.manifest.to_json
       end
     end

lib/propshaft/railtie.rb

@@ -34,6 +34,7 @@ class Railtie < ::Rails::Railtie
       config.assets.relative_url_root ||= app.config.relative_url_root
       config.assets.output_path ||=
         Pathname.new(File.join(app.config.paths["public"].first, app.config.assets.prefix))
+      config.assets.manifest_path ||= config.assets.output_path.join(".manifest.json")
 
       app.assets = Propshaft::Assembly.new(app.config.assets)