Add latest changes from gitlab-org/gitlab@master

1 files changed, 67 insertions, 0 deletions

diff --git a/lib/gitlab/experiment/rollout/feature.rb b/lib/gitlab/experiment/rollout/feature.rb
new file mode 100644
index 00000000000..5a14e3c272e
--- /dev/null
+++ b/lib/gitlab/experiment/rollout/feature.rb
@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+module Gitlab
+  class Experiment
+    module Rollout
+      class Feature < Percent
+        # For this rollout strategy to consider an experiment as enabled, we
+        # must:
+        #
+        # - have a feature flag yaml file that declares it.
+        # - be in an environment that permits it.
+        # - not have rolled out the feature flag at all (no percent of actors,
+        #   no inclusions, etc.)
+        def enabled?
+          return false if ::Feature::Definition.get(feature_flag_name).nil?
+          return false unless Gitlab.dev_env_or_com?
+
+          ::Feature.get(feature_flag_name).state != :off # rubocop:disable Gitlab/AvoidFeatureGet
+        end
+
+        # For assignment we first check to see if our feature flag is enabled
+        # for "self". This is done by calling `#flipper_id` (used behind the
+        # scenes by `Feature`). By default this is our `experiment.id` (or more
+        # specifically, the context key, which is an anonymous SHA generated
+        # using the details of an experiment.
+        #
+        # If the `Feature.enabled?` check is false, we return nil implicitly,
+        # which will assign the control. Otherwise we call super, which will
+        # assign a variant evenly, or based on our provided distribution rules.
+        def execute_assigment
+          super if ::Feature.enabled?(feature_flag_name, self, type: :experiment, default_enabled: :yaml)
+        end
+
+        # NOTE: There's a typo in the name of this method that we'll fix up.
+        alias_method :execute_assignment, :execute_assigment
+
+        # This is what's provided to the `Feature.enabled?` call that will be
+        # used to determine experiment inclusion. An experiment may provide an
+        # override for this method to make the experiment work on user, group,
+        # or projects.
+        #
+        # For example, when running an experiment on a project, you could make
+        # the experiment assignable by project (using chatops) by implementing
+        # a `flipper_id` method in the experiment:
+        #
+        # def flipper_id
+        #   context.project.flipper_id
+        # end
+        #
+        # Or even cleaner, simply delegate it:
+        #
+        # delegate :flipper_id, to: -> { context.project }
+        def flipper_id
+          return experiment.flipper_id if experiment.respond_to?(:flipper_id)
+
+          "Experiment;#{id}"
+        end
+
+        private
+
+        def feature_flag_name
+          experiment.name.tr('/', '_')
+        end
+      end
+    end
+  end
+end