Run feature specs through Workhorse

In development and production, Workhorse is an essential part of how
GitLab operates. However, it is currently excluded from tests. This
makes it hard to approach features that rely on workhorse - like file
uploads - in a test-driven manner.

Introducing workhorse into the test suite for feature specs seems to
have minimal speed impact, and should help significantly with this.

config/gitlab.yml.example

@@ -1226,6 +1226,8 @@ test:
   gitaly:
     client_path: tmp/tests/gitaly
     token: secret
+  workhorse:
+    secret_file: tmp/tests/gitlab_workhorse_secret
   backup:
     path: tmp/tests/backups
   pseudonymizer:

spec/support/capybara.rb

@@ -23,6 +23,18 @@ JS_CONSOLE_FILTER = Regexp.union([
 
 CAPYBARA_WINDOW_SIZE = [1366, 768].freeze
 
+# Run Workhorse on the given host and port, proxying to Puma on a UNIX socket,
+# for a closer-to-production experience
+Capybara.register_server :puma_via_workhorse do |app, port, host, **options|
+  file = Tempfile.new
+  socket_path = file.path
+  file.close! # We just want the filename
+
+  TestEnv.with_workhorse(TestEnv.workhorse_dir, host, port, socket_path) do
+    Capybara.servers[:puma].call(app, nil, socket_path, **options)
+  end
+end
+
 Capybara.register_driver :chrome do |app|
   capabilities = Selenium::WebDriver::Remote::Capabilities.chrome(
     # This enables access to logs with `page.driver.manage.get_log(:browser)`
@@ -60,7 +72,7 @@ Capybara.register_driver :chrome do |app|
   )
 end
 
-Capybara.server = :puma
+Capybara.server = :puma_via_workhorse
 Capybara.javascript_driver = :chrome
 Capybara.default_max_wait_time = timeout
 Capybara.ignore_hidden_elements = true

spec/support/helpers/test_env.rb

@@ -104,6 +104,9 @@ module TestEnv
 
     setup_gitaly
 
+    # Feature specs are run through Workhorse
+    setup_workhorse
+
     # Create repository for FactoryBot.create(:project)
     setup_factory_repo
 
@@ -218,6 +221,52 @@ module TestEnv
     ENV.fetch('GITALY_REPO_URL', nil)
   end
 
+  def setup_workhorse
+    install_workhorse_args = [workhorse_dir, workhorse_url].compact.join(',')
+
+    component_timed_setup(
+      'GitLab Workhorse',
+      install_dir: workhorse_dir,
+      version: Gitlab::Workhorse.version,
+      task: "gitlab:workhorse:install[#{install_workhorse_args}]"
+    )
+  end
+
+  def workhorse_dir
+    @workhorse_path ||= File.join('tmp', 'tests', 'gitlab-workhorse')
+  end
+
+  def with_workhorse(workhorse_dir, host, port, upstream, &blk)
+    host = "[#{host}]" if host.include?(':')
+    listen_addr = [host, port].join(':')
+
+    workhorse_pid = spawn(
+      File.join(workhorse_dir, 'gitlab-workhorse'),
+      '-authSocket', upstream,
+      '-documentRoot', Rails.root.join('public').to_s,
+      '-listenAddr', listen_addr,
+      '-secretPath', Gitlab::Workhorse.secret_path.to_s,
+      # TODO: Needed for workhorse + redis features.
+      # https://gitlab.com/gitlab-org/gitlab/-/issues/209245
+      #
+      # '-config', '',
+      '-logFile', 'log/workhorse-test.log',
+      '-logFormat', 'structured',
+      '-developmentMode' # to serve assets and rich error messages
+    )
+
+    begin
+      yield
+    ensure
+      Process.kill('TERM', workhorse_pid)
+      Process.wait(workhorse_pid)
+    end
+  end
+
+  def workhorse_url
+    ENV.fetch('GITLAB_WORKHORSE_URL', nil)
+  end
+
   def setup_factory_repo
     setup_repo(factory_repo_path, factory_repo_path_bare, factory_repo_name,
                BRANCH_SHA)
@@ -347,6 +396,8 @@ module TestEnv
       gitlab-test_bare
       gitlab-test-fork
       gitlab-test-fork_bare
+      gitlab-workhorse
+      gitlab_workhorse_secret
     ]
   end