Add tracking to measure the number of unique users committing CI config

Whenever a user's commit merged/pushed into the main branch,
we send a track event to Redis HHL.

app/services/git/branch_hooks_service.rb

@@ -44,11 +44,7 @@ module Git
     def invalidated_file_types
       return super unless default_branch? && !creating_branch?
 
-      paths = limited_commits.each_with_object(Set.new) do |commit, set|
-        commit.raw_deltas.each do |diff|
-          set << diff.new_path
-        end
-      end
+      paths = commit_paths.values.reduce(&:merge) || Set.new
 
       Gitlab::FileDetector.types_in_paths(paths)
     end
@@ -77,6 +73,7 @@ module Git
       enqueue_process_commit_messages
       enqueue_jira_connect_sync_messages
       enqueue_metrics_dashboard_sync
+      track_ci_config_change_event
     end
 
     def branch_remove_hooks
@@ -89,6 +86,18 @@ module Git
       ::Metrics::Dashboard::SyncDashboardsWorker.perform_async(project.id)
     end
 
+    def track_ci_config_change_event
+      return unless Gitlab::CurrentSettings.usage_ping_enabled?
+      return unless ::Feature.enabled?(:usage_data_unique_users_committing_ciconfigfile, project, default_enabled: :yaml)
+      return unless default_branch?
+
+      commits_changing_ci_config.each do |commit|
+        Gitlab::UsageDataCounters::HLLRedisCounter.track_event(
+          'o_pipeline_authoring_unique_users_committing_ciconfigfile', values: commit.author&.id
+        )
+      end
+    end
+
     # Schedules processing of commit messages
     def enqueue_process_commit_messages
       referencing_commits = limited_commits.select(&:matches_cross_reference_regex?)
@@ -190,6 +199,23 @@ module Git
 
       set
     end
+
+    def commits_changing_ci_config
+      commit_paths.select do |commit, paths|
+        next if commit.merge_commit?
+
+        paths.include?(project.ci_config_path_or_default)
+      end.keys
+    end
+
+    def commit_paths
+      strong_memoize(:commit_paths) do
+        limited_commits.map do |commit|
+          paths = Set.new(commit.raw_deltas.map(&:new_path))
+          [commit, paths]
+        end.to_h
+      end
+    end
   end
 end
 

config/feature_flags/development/usage_data_unique_users_committing_ciconfigfile.yml

+---
+name: usage_data_unique_users_committing_ciconfigfile
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52172
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/299403
+milestone: '13.9'
+type: development
+group: group::pipeline authoring
+default_enabled: false

lib/gitlab/usage_data_counters/known_events/common.yml

@@ -603,3 +603,9 @@
   redis_slot: ci_templates
   aggregation: weekly
   feature_flag: usage_data_track_ci_templates_unique_projects
+# Pipeline Authoring
+- name: o_pipeline_authoring_unique_users_committing_ciconfigfile
+  category: pipeline_authoring
+  redis_slot: pipeline_authoring
+  aggregation: weekly
+  feature_flag: usage_data_unique_users_committing_ciconfigfile

spec/lib/gitlab/usage_data_counters/hll_redis_counter_spec.rb

@@ -40,7 +40,8 @@ RSpec.describe Gitlab::UsageDataCounters::HLLRedisCounter, :clean_gitlab_redis_s
         'code_review',
         'terraform',
         'ci_templates',
-        'quickactions'
+        'quickactions',
+        'pipeline_authoring'
       )
     end
   end

spec/lib/gitlab/usage_data_spec.rb

@@ -1324,7 +1324,9 @@ RSpec.describe Gitlab::UsageData, :aggregate_failures do
     subject { described_class.redis_hll_counters }
 
     let(:categories) { ::Gitlab::UsageDataCounters::HLLRedisCounter.categories }
-    let(:ineligible_total_categories) { %w[source_code ci_secrets_management incident_management_alerts snippets terraform] }
+    let(:ineligible_total_categories) do
+      %w[source_code ci_secrets_management incident_management_alerts snippets terraform pipeline_authoring]
+    end
 
     it 'has all known_events' do
       expect(subject).to have_key(:redis_hll_counters)

spec/services/git/branch_hooks_service_spec.rb

@@ -93,12 +93,12 @@ RSpec.describe Git::BranchHooksService do
   describe 'Push Event' do
     let(:event) { Event.pushed_action.first }
 
-    before do
-      service.execute
-    end
+    subject(:execute_service) { service.execute }
 
     context "with an existing branch" do
       it 'generates a push event with one commit' do
+        execute_service
+
         expect(event).to be_an_instance_of(PushEvent)
         expect(event.project).to eq(project)
         expect(event).to be_pushed_action
@@ -109,12 +109,87 @@ RSpec.describe Git::BranchHooksService do
         expect(event.push_event_payload.ref).to eq('master')
         expect(event.push_event_payload.commit_count).to eq(1)
       end
+
+      context 'with changing CI config' do
+        before do
+          allow_next_instance_of(Gitlab::Git::Diff) do |diff|
+            allow(diff).to receive(:new_path).and_return('.gitlab-ci.yml')
+          end
+
+          allow(Gitlab::UsageDataCounters::HLLRedisCounter).to receive(:track_event)
+        end
+
+        let!(:commit_author) { create(:user, email: sample_commit.author_email) }
+
+        let(:tracking_params) do
+          ['o_pipeline_authoring_unique_users_committing_ciconfigfile', values: commit_author.id]
+        end
+
+        it 'tracks the event' do
+          execute_service
+
+          expect(Gitlab::UsageDataCounters::HLLRedisCounter)
+            .to have_received(:track_event).with(*tracking_params)
+        end
+
+        context 'when the FF usage_data_unique_users_committing_ciconfigfile is disabled' do
+          before do
+            stub_feature_flags(usage_data_unique_users_committing_ciconfigfile: false)
+          end
+
+          it 'does not track the event' do
+            execute_service
+
+            expect(Gitlab::UsageDataCounters::HLLRedisCounter)
+              .not_to have_received(:track_event).with(*tracking_params)
+          end
+        end
+
+        context 'when usage ping is disabled' do
+          before do
+            stub_application_setting(usage_ping_enabled: false)
+          end
+
+          it 'does not track the event' do
+            execute_service
+
+            expect(Gitlab::UsageDataCounters::HLLRedisCounter)
+              .not_to have_received(:track_event).with(*tracking_params)
+          end
+        end
+
+        context 'when the branch is not the main branch' do
+          let(:branch) { 'feature' }
+
+          it 'does not track the event' do
+            execute_service
+
+            expect(Gitlab::UsageDataCounters::HLLRedisCounter)
+              .not_to have_received(:track_event).with(*tracking_params)
+          end
+        end
+
+        context 'when the CI config is a different path' do
+          before do
+            project.ci_config_path = 'config/ci.yml'
+          end
+
+          it 'does not track the event' do
+            execute_service
+
+            expect(Gitlab::UsageDataCounters::HLLRedisCounter)
+              .not_to have_received(:track_event).with(*tracking_params)
+          end
+        end
+      end
     end
 
     context "with a new branch" do
       let(:oldrev) { Gitlab::Git::BLANK_SHA }
 
       it 'generates a push event with more than one commit' do
+        execute_service
+
         expect(event).to be_an_instance_of(PushEvent)
         expect(event.project).to eq(project)
         expect(event).to be_pushed_action
@@ -131,6 +206,8 @@ RSpec.describe Git::BranchHooksService do
       let(:newrev) { Gitlab::Git::BLANK_SHA }
 
       it 'generates a push event with no commits' do
+        execute_service
+
         expect(event).to be_an_instance_of(PushEvent)
         expect(event.project).to eq(project)
         expect(event).to be_pushed_action