1 files changed, 29 insertions, 0 deletions
diff --git a/lib/initializer_connections.rb b/lib/initializer_connections.rb
new file mode 100644
index 00000000000..c8a6bb6c511
--- /dev/null
+++ b/lib/initializer_connections.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module InitializerConnections
+  # Prevents any database connections within the block
+  # by using an empty connection handler
+  # rubocop:disable Database/MultipleDatabases
+  def self.with_disabled_database_connections
+    return yield if Gitlab::Utils.to_boolean(ENV['SKIP_RAISE_ON_INITIALIZE_CONNECTIONS'])
+
+    original_handler = ActiveRecord::Base.connection_handler
+
+    dummy_handler = ActiveRecord::ConnectionAdapters::ConnectionHandler.new
+    ActiveRecord::Base.connection_handler = dummy_handler
+
+    yield
+
+    if dummy_handler&.connection_pool_names&.present?
+      raise "Unxpected connection_pools (#{dummy_handler.connection_pool_names}) ! Call `connects_to` before this block"
+    end
+  rescue ActiveRecord::ConnectionNotEstablished
+    message = "Database connection should not be called during initializers. Read more at https://docs.gitlab.com/ee/development/rails_initializers.html#database-connections-in-initializers"
+
+    raise message
+  ensure
+    ActiveRecord::Base.connection_handler = original_handler
+    dummy_handler&.clear_all_connections!
+  end
+  # rubocop:enable Database/MultipleDatabases
+end