Switch use of Rack::Request to ActionDispatch::Request

As mentioned in
https://gitlab.com/gitlab-org/gitlab-ee/issues/9035#note_129093444,
Rails 5 switched ActionDispatch::Request so that it no longer inherits
Rack::Request directly. A middleware that uses Rack::Request to
read the environment may see stale request parameters if
another middleware modifies the environment via ActionDispatch::Request.
To be safe, we should be using ActionDispatch::Request everywhere.

lib/api/helpers.rb

@@ -512,7 +512,7 @@ module API
     # `request`. We workaround this by defining methods that returns the right
     # values.
     def define_params_for_grape_middleware
-      self.define_singleton_method(:request) { Rack::Request.new(env) }
+      self.define_singleton_method(:request) { ActionDispatch::Request.new(env) }
       self.define_singleton_method(:params) { request.params.symbolize_keys }
     end

lib/gitlab/etag_caching/middleware.rb

@@ -8,7 +8,7 @@ module Gitlab
       end
       def call(env)
-        request = Rack::Request.new(env)
+        request = ActionDispatch::Request.new(env)
         route = Gitlab::EtagCaching::Router.match(request.path_info)
         return @app.call(env) unless route

lib/gitlab/middleware/basic_health_check.rb

@@ -24,7 +24,7 @@ module Gitlab
       def call(env)
         return @app.call(env) unless env['PATH_INFO'] == HEALTH_PATH
-        request = Rack::Request.new(env)
+        request = ActionDispatch::Request.new(env)
         return OK_RESPONSE if client_ip_whitelisted?(request)

lib/gitlab/middleware/read_only/controller.rb

@@ -60,7 +60,7 @@ module Gitlab
         end
         def request
-          @env['rack.request'] ||= Rack::Request.new(@env)
+          @env['actionpack.request'] ||= ActionDispatch::Request.new(@env)
         end
         def last_visited_url

lib/gitlab/request_context.rb

@@ -13,7 +13,7 @@ module Gitlab
     end
     def call(env)
-      req = Rack::Request.new(env)
+      req = ActionDispatch::Request.new(env)
       Gitlab::SafeRequestStore[:client_ip] = req.ip

spec/lib/gitlab/auth/user_auth_finders_spec.rb

@@ -9,7 +9,7 @@ describe Gitlab::Auth::UserAuthFinders do
       'rack.input' => ''
     }
   end
-  let(:request) { Rack::Request.new(env) }
+  let(:request) { ActionDispatch::Request.new(env) }
   def set_param(key, value)
     request.update_param(key, value)

spec/lib/gitlab/request_context_spec.rb

@@ -15,7 +15,7 @@ describe Gitlab::RequestContext do
         let(:ip) { '192.168.1.11' }
         before do
-          allow_any_instance_of(Rack::Request).to receive(:ip).and_return(ip)
+          allow_any_instance_of(ActionDispatch::Request).to receive(:ip).and_return(ip)
           described_class.new(app).call(env)
         end

spec/lib/omni_auth/strategies/jwt_spec.rb

@@ -25,6 +25,8 @@ describe OmniAuth::Strategies::Jwt do
       subject.options[:secret] = secret
       subject.options[:algorithm] = algorithm
+      # We use Rack::Request instead of ActionDispatch::Request because
+      # Rack::Test::Methods enables testing of this module.
       expect_next_instance_of(Rack::Request) do |rack_request|
         expect(rack_request).to receive(:params).and_return('jwt' => payload)
       end

spec/requests/git_http_spec.rb

@@ -387,7 +387,7 @@ describe 'Git HTTP requests' do
               it "responds with status 401" do
                 expect(Rack::Attack::Allow2Ban).to receive(:filter).and_return(true)
-                allow_any_instance_of(Rack::Request).to receive(:ip).and_return('1.2.3.4')
+                allow_any_instance_of(ActionDispatch::Request).to receive(:ip).and_return('1.2.3.4')
                 clone_get(path, env)
@@ -548,7 +548,7 @@ describe 'Git HTTP requests' do
                   maxretry = options[:maxretry] - 1
                   ip = '1.2.3.4'
-                  allow_any_instance_of(Rack::Request).to receive(:ip).and_return(ip)
+                  allow_any_instance_of(ActionDispatch::Request).to receive(:ip).and_return(ip)
                   Rack::Attack::Allow2Ban.reset(ip, options)
                   maxretry.times.each do