Add Scalability/FileUploads cop

This cop prevents you from using file in API, it points you to the
development documentation about workhorse file acceleration.

9 files changed, 135 insertions, 4 deletions

diff --git a/.rubocop.yml b/.rubocop.yml
index f24cbb6ce92..73743ebf9a2 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -275,3 +275,8 @@ RSpec/BeSuccessMatcher:
     - 'ee/spec/support/shared_examples/controllers/**/*'
     - 'spec/support/controllers/**/*'
     - 'ee/spec/support/controllers/**/*'
+Scalability/FileUploads:
+  Enabled: true
+  Include:
+    - 'lib/api/**/*.rb'
+    - 'ee/lib/api/**/*.rb'
diff --git a/lib/api/helpers/projects_helpers.rb b/lib/api/helpers/projects_helpers.rb
index 51b7cf05c8f..c1e7af33235 100644
--- a/lib/api/helpers/projects_helpers.rb
+++ b/lib/api/helpers/projects_helpers.rb
@@ -38,7 +38,8 @@ module API
         optional :only_allow_merge_if_pipeline_succeeds, type: Boolean, desc: 'Only allow to merge if builds succeed'
         optional :only_allow_merge_if_all_discussions_are_resolved, type: Boolean, desc: 'Only allow to merge if all discussions are resolved'
         optional :tag_list, type: Array[String], desc: 'The list of tags for a project'
-        optional :avatar, type: File, desc: 'Avatar image for project'
+        # TODO: remove rubocop disable - https://gitlab.com/gitlab-org/gitlab-ee/issues/14960
+        optional :avatar, type: File, desc: 'Avatar image for project' # rubocop:disable Scalability/FileUploads
         optional :printing_merge_request_link_enabled, type: Boolean, desc: 'Show link to create/view merge request when pushing from the command line'
         optional :merge_method, type: String, values: %w(ff rebase_merge merge), desc: 'The merge method used when merging merge requests'
         optional :initialize_with_readme, type: Boolean, desc: "Initialize a project with a README.md"
diff --git a/lib/api/pages_domains.rb b/lib/api/pages_domains.rb
index 4227a106a95..40b133e8959 100644
--- a/lib/api/pages_domains.rb
+++ b/lib/api/pages_domains.rb
@@ -90,8 +90,11 @@ module API
       end
       params do
         requires :domain, type: String, desc: 'The domain'
+        # rubocop:disable Scalability/FileUploads
+        # TODO: remove rubocop disable - https://gitlab.com/gitlab-org/gitlab-ee/issues/14960
         optional :certificate, allow_blank: false, types: [File, String], desc: 'The certificate', as: :user_provided_certificate
         optional :key, allow_blank: false, types: [File, String], desc: 'The key', as: :user_provided_key
+        # rubocop:enable Scalability/FileUploads
         all_or_none_of :user_provided_certificate, :user_provided_key
       end
       post ":id/pages/domains" do
@@ -111,8 +114,11 @@ module API
       desc 'Updates a pages domain'
       params do
         requires :domain, type: String, desc: 'The domain'
+        # rubocop:disable Scalability/FileUploads
+        # TODO: remove rubocop disable - https://gitlab.com/gitlab-org/gitlab-ee/issues/14960
         optional :certificate, allow_blank: false, types: [File, String], desc: 'The certificate', as: :user_provided_certificate
         optional :key, allow_blank: false, types: [File, String], desc: 'The key', as: :user_provided_key
+        # rubocop:enable Scalability/FileUploads
       end
       put ":id/pages/domains/:domain", requirements: PAGES_DOMAINS_ENDPOINT_REQUIREMENTS do
         authorize! :update_pages, user_project
diff --git a/lib/api/project_import.rb b/lib/api/project_import.rb
index bb1b037c08f..9b5e0727184 100644
--- a/lib/api/project_import.rb
+++ b/lib/api/project_import.rb
@@ -27,7 +27,8 @@ module API
     resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
       params do
         requires :path, type: String, desc: 'The new project path and name'
-        requires :file, type: File, desc: 'The project export file to be imported'
+        # TODO: remove rubocop disable - https://gitlab.com/gitlab-org/gitlab-ee/issues/14960
+        requires :file, type: File, desc: 'The project export file to be imported' # rubocop:disable Scalability/FileUploads
         optional :namespace, type: String, desc: "The ID or name of the namespace that the project will be imported into. Defaults to the current user's namespace."
         optional :overwrite, type: Boolean, default: false, desc: 'If there is a project in the same namespace and with the same name overwrite it'
         optional :override_params,
diff --git a/lib/api/projects.rb b/lib/api/projects.rb
index 3073c14b341..63bfa8db61c 100644
--- a/lib/api/projects.rb
+++ b/lib/api/projects.rb
@@ -478,7 +478,8 @@ module API
 
       desc 'Upload a file'
       params do
-        requires :file, type: File, desc: 'The file to be uploaded'
+        # TODO: remove rubocop disable - https://gitlab.com/gitlab-org/gitlab-ee/issues/14960
+        requires :file, type: File, desc: 'The file to be uploaded' # rubocop:disable Scalability/FileUploads
       end
       post ":id/uploads" do
         UploadService.new(user_project, params[:file]).execute.to_h
diff --git a/lib/api/users.rb b/lib/api/users.rb
index a4ac5b629b8..99295888c8c 100644
--- a/lib/api/users.rb
+++ b/lib/api/users.rb
@@ -50,7 +50,8 @@ module API
           optional :admin, type: Boolean, desc: 'Flag indicating the user is an administrator'
           optional :can_create_group, type: Boolean, desc: 'Flag indicating the user can create groups'
           optional :external, type: Boolean, desc: 'Flag indicating the user is an external user'
-          optional :avatar, type: File, desc: 'Avatar image for user'
+          # TODO: remove rubocop disable - https://gitlab.com/gitlab-org/gitlab-ee/issues/14960
+          optional :avatar, type: File, desc: 'Avatar image for user' # rubocop:disable Scalability/FileUploads
           optional :private_profile, type: Boolean, default: false, desc: 'Flag indicating the user has a private profile'
           all_or_none_of :extern_uid, :provider
 
diff --git a/rubocop/cop/scalability/file_uploads.rb b/rubocop/cop/scalability/file_uploads.rb
new file mode 100644
index 00000000000..83017217e32
--- /dev/null
+++ b/rubocop/cop/scalability/file_uploads.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Scalability
+      # This cop checks for `File` params in API
+      #
+      # @example
+      #
+      #   # bad
+      #   params do
+      #     requires :file, type: File
+      #   end
+      #
+      #   params do
+      #     optional :file, type: File
+      #   end
+      #
+      #   # good
+      #   params do
+      #     requires :file, type: ::API::Validations::Types::WorkhorseFile
+      #   end
+      #
+      #   params do
+      #     optional :file, type: ::API::Validations::Types::WorkhorseFile
+      #   end
+      #
+      class FileUploads < RuboCop::Cop::Cop
+        MSG = 'Do not upload files without workhorse acceleration. Please refer to https://docs.gitlab.com/ee/development/uploads.html'
+
+        def_node_search :file_type_params?, <<~PATTERN
+          (send nil? {:requires :optional} (sym _) (hash <(pair (sym :type)(const nil? :File)) ...>))
+        PATTERN
+
+        def_node_search :file_types_params?, <<~PATTERN
+          (send nil? {:requires :optional} (sym _) (hash <(pair (sym :types)(array <(const nil? :File) ...>)) ...>))
+        PATTERN
+
+        def be_file_param_usage?(node)
+          file_type_params?(node) || file_types_params?(node)
+        end
+
+        def on_send(node)
+          return unless be_file_param_usage?(node)
+
+          add_offense(find_file_param(node), location: :expression)
+        end
+
+        private
+
+        def find_file_param(node)
+          node.each_descendant.find { |children| file_node_pattern.match(children) }
+        end
+
+        def file_node_pattern
+          @file_node_pattern ||= RuboCop::NodePattern.new("(const nil? :File)")
+        end
+      end
+    end
+  end
+end
diff --git a/rubocop/rubocop.rb b/rubocop/rubocop.rb
index c342df6d6c9..9d97aa86bf6 100644
--- a/rubocop/rubocop.rb
+++ b/rubocop/rubocop.rb
@@ -37,6 +37,7 @@ require_relative 'cop/rspec/factories_in_migration_specs'
 require_relative 'cop/rspec/top_level_describe_path'
 require_relative 'cop/qa/element_with_pattern'
 require_relative 'cop/sidekiq_options_queue'
+require_relative 'cop/scalability/file_uploads'
 require_relative 'cop/destroy_all'
 require_relative 'cop/ruby_interpolation_in_translation'
 require_relative 'code_reuse_helpers'
diff --git a/spec/rubocop/cop/scalability/file_uploads_spec.rb b/spec/rubocop/cop/scalability/file_uploads_spec.rb
new file mode 100644
index 00000000000..2a94fde5ba2
--- /dev/null
+++ b/spec/rubocop/cop/scalability/file_uploads_spec.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require 'rubocop'
+require_relative '../../../support/helpers/expect_offense'
+require_relative '../../../../rubocop/cop/scalability/file_uploads'
+
+describe RuboCop::Cop::Scalability::FileUploads do
+  include CopHelper
+  include ExpectOffense
+
+  subject(:cop) { described_class.new }
+  let(:message) { 'Do not upload files without workhorse acceleration. Please refer to https://docs.gitlab.com/ee/development/uploads.html' }
+
+  context 'with required params' do
+    it 'detects File in types array' do
+      expect_offense(<<~PATTERN.strip_indent)
+      params do
+        requires :certificate, allow_blank: false, types: [String, File]
+                                                                   ^^^^ #{message}
+      end
+      PATTERN
+    end
+
+    it 'detects File as type argument' do
+      expect_offense(<<~PATTERN.strip_indent)
+      params do
+        requires :attachment, type: File
+                                    ^^^^ #{message}
+      end
+      PATTERN
+    end
+  end
+
+  context 'with optional params' do
+    it 'detects File in types array' do
+      expect_offense(<<~PATTERN.strip_indent)
+      params do
+        optional :certificate, allow_blank: false, types: [String, File]
+                                                                   ^^^^ #{message}
+      end
+      PATTERN
+    end
+
+    it 'detects File as type argument' do
+      expect_offense(<<~PATTERN.strip_indent)
+      params do
+        optional :attachment, type: File
+                                    ^^^^ #{message}
+      end
+      PATTERN
+    end
+  end
+end