Merge branch 'sh-fix-sidekiq-admin-cng' into 'master'

Disable Sendfile interface for serving Sidekiq Web assets

See merge request gitlab-org/gitlab!70113

config/initializers/static_files.rb

@@ -2,6 +2,10 @@
 
 app = Rails.application
 
+# Disable Sendfile for Sidekiq Web assets since Workhorse won't
+# always have access to these files.
+app.config.middleware.insert_before(Rack::Sendfile, Gitlab::Middleware::SidekiqWebStatic)
+
 if app.config.public_file_server.enabled
   # The `ActionDispatch::Static` middleware intercepts requests for static files
   # by checking if they exist in the `/public` directory.

lib/gitlab/middleware/sidekiq_web_static.rb

+# frozen_string_literal: true
+
+# This module removes the X-Sendfile-Type header for /admin/sidekiq
+# assets since Workhorse isn't always guaranteed to have the assets
+# present on disk, such as when using Cloud Native GitLab
+# containers. These assets are also small and served infrequently so it
+# should be fine to do this.
+module Gitlab
+  module Middleware
+    class SidekiqWebStatic
+      SIDEKIQ_REGEX = %r{\A/admin/sidekiq/}.freeze
+
+      def initialize(app)
+        @app = app
+      end
+
+      def call(env)
+        env.delete('HTTP_X_SENDFILE_TYPE') if env['PATH_INFO'] =~ SIDEKIQ_REGEX
+
+        @app.call(env)
+      end
+    end
+  end
+end

spec/lib/gitlab/middleware/sidekiq_web_static_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Middleware::SidekiqWebStatic do
+  let(:app) { double(:app) }
+  let(:middleware) { described_class.new(app) }
+  let(:env) { {} }
+
+  describe '#call' do
+    before do
+      env['HTTP_X_SENDFILE_TYPE'] = 'X-Sendfile'
+      env['PATH_INFO'] = path
+    end
+
+    context 'with an /admin/sidekiq route' do
+      let(:path) { '/admin/sidekiq/javascripts/application.js'}
+
+      it 'deletes the HTTP_X_SENDFILE_TYPE header' do
+        expect(app).to receive(:call)
+
+        middleware.call(env)
+
+        expect(env['HTTP_X_SENDFILE_TYPE']).to be_nil
+      end
+    end
+
+    context 'with some static asset route' do
+      let(:path) { '/assets/test.png' }
+
+      it 'keeps the HTTP_X_SENDFILE_TYPE header' do
+        expect(app).to receive(:call)
+
+        middleware.call(env)
+
+        expect(env['HTTP_X_SENDFILE_TYPE']).to eq('X-Sendfile')
+      end
+    end
+  end
+end