1 files changed, 126 insertions, 0 deletions
diff --git a/lib/gitlab/etag_caching/router/rails.rb b/lib/gitlab/etag_caching/router/rails.rb
new file mode 100644
index 00000000000..d80c003fe53
--- /dev/null
+++ b/lib/gitlab/etag_caching/router/rails.rb
@@ -0,0 +1,126 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module EtagCaching
+    module Router
+      class Rails
+        extend EtagCaching::Router::Helpers
+
+        # We enable an ETag for every request matching the regex.
+        # To match a regex the path needs to match the following:
+        #   - Don't contain a reserved word (expect for the words used in the
+        #     regex itself)
+        #   - Ending in `noteable/issue/<id>/notes` for the `issue_notes` route
+        #   - Ending in `issues/id`/realtime_changes` for the `issue_title` route
+        USED_IN_ROUTES = %w[noteable issue notes issues realtime_changes
+                            commit pipelines merge_requests builds
+                            new environments].freeze
+        RESERVED_WORDS = Gitlab::PathRegex::ILLEGAL_PROJECT_PATH_WORDS - USED_IN_ROUTES
+        RESERVED_WORDS_REGEX = Regexp.union(*RESERVED_WORDS.map(&Regexp.method(:escape)))
+        RESERVED_WORDS_PREFIX = %Q(^(?!.*\/(#{RESERVED_WORDS_REGEX})\/).*)
+
+        ROUTES = [
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/noteable/issue/\d+/notes\z),
+            'issue_notes',
+            ::Projects::NotesController,
+            :index
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/noteable/merge_request/\d+/notes\z),
+            'merge_request_notes',
+            ::Projects::NotesController,
+            :index
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/issues/\d+/realtime_changes\z),
+            'issue_title',
+            ::Projects::IssuesController,
+            :realtime_changes
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/commit/\S+/pipelines\.json\z),
+            'commit_pipelines',
+            ::Projects::CommitController,
+            :pipelines
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/merge_requests/new\.json\z),
+            'new_merge_request_pipelines',
+            ::Projects::MergeRequests::CreationsController,
+            :new
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/merge_requests/\d+/pipelines\.json\z),
+            'merge_request_pipelines',
+            ::Projects::MergeRequestsController,
+            :pipelines
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/pipelines\.json\z),
+            'project_pipelines',
+            ::Projects::PipelinesController,
+            :index
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/pipelines/\d+\.json\z),
+            'project_pipeline',
+            ::Projects::PipelinesController,
+            :show
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/builds/\d+\.json\z),
+            'project_build',
+            ::Projects::BuildsController,
+            :show
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/clusters/\d+/environments\z),
+            'cluster_environments',
+            ::Groups::ClustersController,
+            :environments
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/-/environments\.json\z),
+            'environments',
+            ::Projects::EnvironmentsController,
+            :index
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/import/github/realtime_changes\.json\z),
+            'realtime_changes_import_github',
+            ::Import::GithubController,
+            :realtime_changes
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/import/gitea/realtime_changes\.json\z),
+            'realtime_changes_import_gitea',
+            ::Import::GiteaController,
+            :realtime_changes
+          ],
+          [
+            %r(#{RESERVED_WORDS_PREFIX}/merge_requests/\d+/cached_widget\.json\z),
+            'merge_request_widget',
+            ::Projects::MergeRequests::ContentController,
+            :cached_widget
+          ]
+        ].map(&method(:build_rails_route)).freeze
+
+        # Overridden in EE to add more routes
+        def self.all_routes
+          ROUTES
+        end
+
+        def self.match(request)
+          all_routes.find { |route| route.match(request.path_info) }
+        end
+
+        def self.cache_key(request)
+          request.path
+        end
+      end
+    end
+  end
+end
+
+Gitlab::EtagCaching::Router::Rails.prepend_mod_with('Gitlab::EtagCaching::Router::Rails')