Add a request wrappers that logs out why a console isn't displayed

lib/web_console.rb

@@ -1,6 +1,7 @@
 require 'binding_of_caller'
 
 require 'active_support/lazy_load_hooks'
+require 'active_support/logger'
 
 require 'web_console/core_ext/exception'
 require 'web_console/engine'
@@ -13,7 +14,11 @@
 require 'web_console/middleware'
 require 'web_console/whitelist'
 require 'web_console/request'
+require 'web_console/whiny_request'
 
 module WebConsole
+  mattr_accessor :logger
+  @@logger = ActiveSupport::Logger.new($stderr)
+
   ActiveSupport.run_load_hooks(:web_console, self)
 end

lib/web_console/middleware.rb

@@ -7,13 +7,16 @@ class Middleware
       binding_change_re: %r{/repl_sessions/(?<id>.+?)/trace\z}
     }
 
+    cattr_accessor :whiny_requests
+    @@whiny_requests = true
+
     def initialize(app, options = {})
       @app     = app
       @options = DEFAULT_OPTIONS.merge(options)
     end
 
     def call(env)
-      request = Request.new(env)
+      request = create_request(env)
       return @app.call(env) unless request.from_whitelited_ip?
 
       if id = id_for_repl_session_update(request)
@@ -43,6 +46,11 @@ def call(env)
 
     private
 
+      def create_request(env)
+        request = Request.new(env)
+        whiny_requests ? WhinyRequest.new(request) : request
+      end
+
       def update_re
         @options[:update_re]
       end

lib/web_console/request.rb

@@ -3,9 +3,10 @@ module WebConsole
   class Request < ActionDispatch::Request
     # While most of the servers will return blank content type if none given,
     # Puma will return text/plain.
-    ACCEPTABLE_CONTENT_TYPE = [Mime::HTML, Mime::TEXT]
+    cattr_accessor :acceptable_content_types
+    @@acceptable_content_types = [Mime::HTML, Mime::TEXT]
 
-    # Configurable whitelisted IPs.
+    # Configurable set of whitelisted networks.
     cattr_accessor :whitelisted_ips
     @@whitelisted_ips = Whitelist.new
 
@@ -19,10 +20,11 @@ def from_whitelited_ip?
 
     # Returns whether the request is from an acceptable content type.
     #
-    # We can render a console for HTML and TEXT. If a client didn't
-    # specified any content type, we'll render it as well.
+    # We can render a console for HTML and TEXT by default. If a client didn't
+    # specified any content type and the server returned it as blank, we'll
+    # render it as well.
     def acceptable_content_type?
-      content_type.blank? || content_type.in?(ACCEPTABLE_CONTENT_TYPE)
+      content_type.blank? || content_type.in?(acceptable_content_types)
     end
   end
 end

lib/web_console/whiny_request.rb

@@ -0,0 +1,38 @@
+module WebConsole
+  # Noisy wrapper around +Request+.
+  #
+  # If any calls to +from_whitelisted_ip?+ and +acceptable_content_type?+
+  # return false, an info log message will be displayed in users' logs.
+  class WhinyRequest < SimpleDelegator
+    def from_whitelited_ip?
+      whine_unless request.from_whitelited_ip? do
+        "Cannot render console from #{request.remote_ip}! " \
+          "Allowed networks: #{request.whitelisted_ips}"
+      end
+    end
+
+    def acceptable_content_type?
+      whine_unless request.acceptable_content_type? do
+        "Cannot render console with content type #{request.content_type}" \
+          "Allowed content types: #{request.acceptable_content_types}"
+      end
+    end
+
+    private
+
+      def whine_unless(condition)
+        unless condition
+          logger.info { yield }
+        end
+        condition
+      end
+
+      def logger
+        env['action_dispatch.logger'] || WebConsole.logger
+      end
+
+      def request
+        __getobj__
+      end
+  end
+end

test/test_helper.rb

@@ -23,6 +23,28 @@ def assert_select(*)
   include SilenceRailsDomTesting
 end
 
+# A copy of Kernel#capture in active_support/core_ext/kernel/reporting.rb as
+# its getting deprecated past 4.2. Its not thread safe, but I don't need it to
+# be in the tests
+def capture(stream)
+  stream = stream.to_s
+  captured_stream = Tempfile.new(stream)
+  stream_io = eval("$#{stream}")
+  origin_stream = stream_io.dup
+  stream_io.reopen(captured_stream)
+
+  yield
+
+  stream_io.rewind
+  return captured_stream.read
+ensure
+  captured_stream.close
+  captured_stream.unlink
+  stream_io.reopen(origin_stream)
+end
+
+alias silence capture
+
 # Load fixtures from the engine
 if ActiveSupport::TestCase.method_defined?(:fixture_path=)
   ActiveSupport::TestCase.fixture_path = File.expand_path("../fixtures", __FILE__)

test/web_console/middleware_test.rb

@@ -58,7 +58,9 @@ def call(env)
     test "doesn't render console from non whitelisted IP" do
       Request.stubs(:whitelisted_ips).returns(IPAddr.new('127.0.0.1'))
 
-      get '/', nil, 'CONTENT_TYPE' => 'text/html', 'REMOTE_ADDR' => '1.1.1.1', 'web-console.binding' => binding
+      silence(:stderr) do
+        get '/', nil, 'CONTENT_TYPE' => 'text/html', 'REMOTE_ADDR' => '1.1.1.1', 'web-console.binding' => binding
+      end
 
       assert_select '#console', 0
     end

test/web_console/whiny_request_test.rb

@@ -0,0 +1,33 @@
+require 'test_helper'
+
+module WebConsole
+  class WhinyRequestTest < ActiveSupport::TestCase
+    test '#from_whitelited_ip? logs out to stderr' do
+      Request.stubs(:whitelisted_ips).returns(IPAddr.new('127.0.0.1'))
+      assert_output_to_stderr do
+        req = request('http://example.com', 'REMOTE_ADDR' => '0.0.0.0')
+        assert_not req.from_whitelited_ip?
+      end
+    end
+
+    test '#acceptable_content_type? logs out to stderr' do
+      Request.stubs(:acceptable_content_types).returns([])
+      assert_output_to_stderr do
+        req = request('http://example.com', 'CONTENT_TYPE' => 'application/json')
+        assert_not req.acceptable_content_type?
+      end
+    end
+
+    private
+
+      def assert_output_to_stderr
+        output = capture(:stderr) { yield }
+        assert_not output.blank?
+      end
+
+      def request(*args)
+        request = Request.new(Rack::MockRequest.env_for(*args))
+        WhinyRequest.new(request)
+      end
+  end
+end