Add Rollbar.js integration

Users can now use the gem to configure the Rollbar JS notifier using the
same initializer.

The gem will inject the Rollbar JS snippet and the configuration to the
returned response.

In order to configure the Rollbar.js using the gem, users can follo the
next:

js_config = {
        accessToken: ""POST_CLIENT_ITEM_ACCESS_TOKEN",
        captureUncaught: true,
        payload: {
          environment: "production"
        }
}

Rollbar.configure do |config|
  # common gem configuration
  config.js_enabled = true
  config.js_options = js_config
end

The options passed to `#js_options=` are the same than the used for the
Rollbar JS notifier.

Author: Jon de Andres

.gitignore

@@ -20,3 +20,4 @@ test/version_tmp
 tmp
 *.swp
 .idea/
+gemfiles/vendor

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "rollbar.js"]
+	path = rollbar.js
+	url = https://github.com/rollbar/rollbar.js.git

Rakefile

@@ -11,9 +11,11 @@ desc 'Run specs'
 task :default do
   ENV['LOCAL'] = '1'
   Rake::Task[:spec].invoke
-  
+
   Rake::Task[:spec].reenable
-  
+
   ENV['LOCAL'] = '0'
   Rake::Task[:spec].invoke
-end
+end
+
+Dir.glob('lib/tasks/*.rake').each { |r| load r }

data/rollbar.snippet.js

@@ -11,6 +11,7 @@
 
 require 'rollbar/version'
 require 'rollbar/json'
+require 'rollbar/js'
 require 'rollbar/configuration'
 require 'rollbar/encoding'
 require 'rollbar/logger_proxy'
@@ -781,6 +782,8 @@ def safely?
     end
 
     def require_hooks
+      ::Rollbar::Js.prepare if configuration.js_enabled
+
       return if configuration.disable_monkey_patch
       wrap_delayed_worker
 

lib/rollbar.rb

@@ -32,6 +32,8 @@ class Configuration
     attr_accessor :report_dj_data
     attr_accessor :request_timeout
     attr_accessor :root
+    attr_accessor :js_options
+    attr_accessor :js_enabled
     attr_accessor :safely
     attr_accessor :scrub_fields
     attr_accessor :scrub_user
@@ -84,6 +86,8 @@ def initialize
       @populate_empty_backtraces = false
       @report_dj_data = true
       @request_timeout = 3
+      @js_enabled = true
+      @js_options = {}
       @scrub_fields = [:passwd, :password, :password_confirmation, :secret,
                        :confirm_password, :password_confirmation, :secret_token,
                        :api_key, :access_token ]

lib/rollbar/configuration.rb

@@ -0,0 +1,32 @@
+require "rollbar/js/version"
+
+module Rollbar
+  module Js
+    extend self
+
+    attr_reader :framework
+    attr_reader :framework_loader
+
+    def prepare
+      @framework ||= detect_framework
+      @framework_loader ||= load_framework_class.new
+
+      @framework_loader.prepare
+    end
+
+    private
+
+    def detect_framework
+      case
+      when defined?(::Rails::VERSION)
+        :rails
+      end
+    end
+
+    def load_framework_class
+      require "rollbar/js/frameworks/#{framework}"
+
+      Rollbar::Js::Frameworks.const_get(framework.to_s.capitalize)
+    end
+  end
+end

lib/rollbar/js.rb

@@ -0,0 +1,6 @@
+module Rollbar
+  module Js
+    module Frameworks
+    end
+  end
+end

lib/rollbar/js/frameworks.rb

@@ -0,0 +1,29 @@
+module Rollbar
+  module Js
+    module Frameworks
+      class Rails
+        attr_accessor :prepared
+
+        alias prepared? prepared
+
+        def prepare
+          return if prepared?
+
+          require 'rollbar/js/middleware'
+
+          config = {
+            :options => Rollbar.configuration.js_options,
+            :enabled => Rollbar.configuration.js_enabled
+          }
+          rails_config.middleware.use(::Rollbar::Js::Middleware, config)
+
+          self.prepared = true
+        end
+
+        def rails_config
+          ::Rails.configuration
+        end
+      end
+    end
+  end
+end

lib/rollbar/js/frameworks/rails.rb

@@ -0,0 +1,134 @@
+require 'rack'
+require 'rack/response'
+
+
+module Rollbar
+  module Js
+    class Middleware
+      attr_reader :app
+      attr_reader :config
+
+      JS_IS_INJECTED_KEY = 'rollbar.js_is_injected'
+      SNIPPET = File.read(File.expand_path('../../../../data/rollbar.snippet.js', __FILE__))
+
+      def initialize(app, config)
+        @app = app
+        @config = config
+      end
+
+      def call(env)
+        result = app.call(env)
+
+        status = result[0]
+        headers = result[1]
+        response = result[2]
+
+        return result unless should_add_js?(env, status, headers)
+
+        if response_string = add_js(response)
+          env[JS_IS_INJECTED_KEY] = true
+          response = ::Rack::Response.new(response_string, result[0], result[1])
+
+          response.finish
+        else
+          result
+        end
+      end
+
+      private
+
+      def enabled?
+        !!config[:enabled]
+      end
+
+      def should_add_js?(env, status, headers)
+        enabled? &&
+          status == 200 &&
+          !env[JS_IS_INJECTED_KEY] &&
+          html?(headers) &&
+          !attachment?(headers) &&
+          !streaming?(env)
+      end
+
+      def html?(headers)
+        headers['Content-Type'] && headers['Content-Type'].include?('text/html')
+      end
+
+      def attachment?(headers)
+        headers['Content-Disposition'].to_s.include?('attachment')
+      end
+
+      def streaming?(env)
+        return false unless defined?(ActionController::Live)
+
+        env['action_controller.instance'].class.included_modules.include?(ActionController::Live)
+      end
+
+      def add_js(response)
+        body = join_body(response)
+        close_old_response(response)
+
+        return nil unless body
+
+        head_close = find_end_of_head_open(body)
+        return nil unless head_close
+
+        if head_close
+          body = body[0..head_close] <<
+                 config_js_tag <<
+                 snippet_js_tag <<
+                 body[head_close..-1]
+        end
+
+        body
+      rescue => e
+        Rollbar.log_error("[Rollbar] Rollbar.js could not be added because #{e} exception")
+        nil
+      end
+
+      def find_end_of_head_open(body)
+        head_open = body.index('<head')
+        body.index('>', head_open) + 1 if head_open
+      end
+
+      def join_body(response)
+        source = nil
+        response.each { |fragment| source ? (source << fragment.to_s) : (source = fragment.to_s)}
+        source
+      end
+
+      def close_old_response(response)
+        response.close if response.respond_to?(:close)
+      end
+
+      def calculate_content_length(source)
+        if source.respond_to?(:bytesize)
+          source.bytesize
+        else
+          source.length
+        end
+      end
+
+      def config_js_tag
+        script_tag("var _rollbarConfig = #{config[:options].to_json};")
+      end
+
+      def snippet_js_tag
+        script_tag(js_snippet)
+      end
+
+      def js_snippet
+        @js_snippet ||= SNIPPET
+      end
+
+      def script_tag(content)
+        html_safe_if_needed("\n<script type=\"text/javascript\">#{content}</script>")
+      end
+
+      def html_safe_if_needed(string)
+        string = string.html_safe if string.respond_to?(:html_safe)
+        string
+      end
+    end
+  end
+end