include path parameters in params hash for ruby environment (#249)

* include path parameters in params hash for ruby environment

* Improve code organization and documentation for ruby environment.

* Document Ruby examples

environments/ruby/README.md

@@ -2,9 +2,19 @@
 
 This is the Ruby environment for Fission.
 
-It's a Docker image containing a Ruby 2.4.1 runtime, along with a
-dynamic loader.  A few common dependencies are included in the
-Gemfile.
+It's a Docker image containing a Ruby 2.4.1 runtime. The image uses
+Rack with WEBrick to host the internal web server.
+
+The environment works via convention where you create a Ruby method
+called `handler` with a single optional argument, a `Fission::Context`
+object.
+
+The `Fission::Context` object gives access to the Rack env, and a
+request object. Please see `fission/context.rb` for the public api.
+
+The `Fission::Request` object is a subclass of `Rack::Request` and
+provides access to parameters and headers. See `fission/request.rb`
+for the public api.
 
 ## Customizing this image
 
@@ -39,3 +49,7 @@ Or, if you already have an environment, you can update its image:
 
 After this, fission functions that have the env parameter set to the
 same environment name as this command will use this environment.
+
+## Creating functions to use this image
+
+See the [examples README](examples/ruby/README.md).

environments/ruby/fission/context.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require_relative 'request'
+
+module Fission
+  class Context
+    attr_reader :env
+
+    def initialize(env)
+      @env = env
+    end
+
+    def request
+      @request ||= Request.new(env)
+    end
+  end
+end

environments/ruby/fission/handler.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require_relative 'context'
+
+module Fission
+  module Handler
+    def self.call(env)
+      response = if method(:handler).arity > 0
+        handler(Context.new(env))
+      else
+        handler
+      end
+
+      response.is_a?(Array) ? response : Rack::Response.new([response]).finish
+    rescue
+      Rack::Response.new(['500 Internal Server Error'], 500, {}).finish
+    end
+  end
+end

environments/ruby/fission/request.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Fission
+  HEADER_PREFIX = 'HTTP_'
+  PARAM_HEADER_PREFIX = 'HTTP_X_FISSION_PARAMS_'
+  PARAMETERS_KEY = 'fission.request.parameters'
+
+  class Request < Rack::Request
+    def headers
+      Hash[
+        *env.select { |k,v| k.start_with?(HEADER_PREFIX) }
+             .map { |k,v| [k.sub(/\A#{HEADER_PREFIX}/, '').split('_').map(&:capitalize).join('-'), v] }
+             .sort
+             .flatten
+      ]
+    end
+
+    def params
+      env[PARAMETERS_KEY] ||= super.merge(path_parameters)
+    end
+
+    def path_parameters
+      Hash[
+        *env.select { |k,v| k.start_with?(PARAM_HEADER_PREFIX) }
+             .map { |k,v| [k.sub(/\A#{PARAM_HEADER_PREFIX}/, '').downcase, v] }
+             .sort
+             .flatten
+      ]
+    end
+  end
+end

environments/ruby/fission/specializer.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+module Fission
+  CODE_PATH = '/userfunc/user'
+
+  module Specializer
+    def self.call(env)
+      load CODE_PATH
+      Rack::Response.new([], 201).finish
+    rescue
+      Rack::Response.new(['500 Internal Server Error'], 500, {}).finish
+    end
+  end
+end

environments/ruby/server.rb

@@ -1,55 +1,9 @@
 # frozen_string_literal: true
+
 require 'rack'
 
-CODEPATH = '/userfunc/user'
-
-module Fission
-  class Request < Rack::Request
-    def headers
-      Hash[
-        *env.select { |k,v| k.start_with?('HTTP_') }
-             .map { |k,v| [k.sub(/\AHTTP_/, '').split('_').map(&:capitalize).join('-'), v] }
-             .sort
-             .flatten
-      ]
-    end
-  end
-
-  class Context
-    attr_reader :env
-
-    def initialize(env)
-      @env = env
-    end
-
-    def request
-      @request ||= Request.new(env)
-    end
-  end
-
-  module Specializer
-    def self.call(env)
-      load CODEPATH
-      Rack::Response.new([], 201).finish
-    rescue
-      Rack::Response.new(['500 Internal Server Error'], 500, {}).finish
-    end
-  end
-
-  module Handler
-    def self.call(env)
-      response = if method(:handler).arity > 0
-        handler(Context.new(env))
-      else
-        handler
-      end
-
-      response.is_a?(Array) ? response : Rack::Response.new([response]).finish
-    rescue
-      Rack::Response.new(['500 Internal Server Error'], 500, {}).finish
-    end
-  end
-end
+require_relative 'fission/specializer'
+require_relative 'fission/handler'
 
 app = Rack::Builder.new do
   use Rack::CommonLogger, $stderr