Implement tracking number of unique users pushing MRs for CI config

When a user pushes changes including the CI config, we track it
using RedisHLL.
Event name: o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile
Feature flag:
usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile

app/models/merge_request.rb

@@ -1863,6 +1863,12 @@ class MergeRequest < ApplicationRecord
     }
   end
 
+  def includes_ci_config?
+    return false unless diff_stats
+
+    diff_stats.map(&:path).include?(project.ci_config_path_or_default)
+  end
+
   private
 
   def missing_report_error(report_type)

app/services/merge_requests/after_create_service.rb

@@ -4,7 +4,10 @@ module MergeRequests
   class AfterCreateService < MergeRequests::BaseService
     def execute(merge_request)
       event_service.open_mr(merge_request, current_user)
+
       merge_request_activity_counter.track_create_mr_action(user: current_user)
+      merge_request_activity_counter.track_mr_including_ci_config(user: current_user, merge_request: merge_request)
+
       notification_service.new_merge_request(merge_request, current_user)
 
       create_pipeline_for(merge_request, current_user)

app/services/merge_requests/refresh_service.rb

@@ -44,6 +44,7 @@ module MergeRequests
         notify_about_push(mr)
         mark_mr_as_draft_from_commits(mr)
         execute_mr_web_hooks(mr)
+        merge_request_activity_counter.track_mr_including_ci_config(user: mr.author, merge_request: mr)
       end
 
       true

config/feature_flags/development/usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile.yml

+---
+name: usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/54707
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/322166
+milestone: '13.10'
+type: development
+group: group::pipeline authoring
+default_enabled: false

config/metrics/counts_28d/20210301144228_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_monthly.yml

+---
+key_path: redis_hll_counters.pipeline_authoring.o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_monthly
+description: Monthly unique user count having merge requests which contains the CI config file
+product_section: ops
+product_stage: verify
+product_group: group::pipeline authoring
+product_category: pipeline_authoring
+value_type: number
+status: implemented
+milestone: "13.10"
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/54707
+time_frame: 28d
+data_source: redis_hll
+distribution:
+- ce
+- ee
+tier:
+- free
+- premium
+- ultimate

config/metrics/counts_7d/20210301144209_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_weekly.yml

+---
+key_path: redis_hll_counters.pipeline_authoring.o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_weekly
+description: Weekly unique user count having merge requests which contains the CI config file
+product_section: ops
+product_stage: verify
+product_group: group::pipeline authoring
+product_category: pipeline_authoring
+value_type: number
+status: implemented
+milestone: "13.10"
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/54707
+time_frame: 7d
+data_source: redis_hll
+distribution:
+- ce
+- ee
+tier:
+- free
+- premium
+- ultimate

doc/development/usage_ping/dictionary.md

@@ -10796,6 +10796,30 @@ Status: `data_available`
 
 Tiers: 
 
+### `redis_hll_counters.pipeline_authoring.o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_monthly`
+
+Monthly unique user count having merge requests which contains the CI config file
+
+[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/metrics/counts_28d/20210301144228_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_monthly.yml)
+
+Group: `group::pipeline authoring`
+
+Status: `implemented`
+
+Tiers: `free`, `premium`, `ultimate`
+
+### `redis_hll_counters.pipeline_authoring.o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_weekly`
+
+Weekly unique user count having merge requests which contains the CI config file
+
+[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/metrics/counts_7d/20210301144209_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile_weekly.yml)
+
+Group: `group::pipeline authoring`
+
+Status: `implemented`
+
+Tiers: `free`, `premium`, `ultimate`
+
 ### `redis_hll_counters.quickactions.i_quickactions_approve_monthly`
 
 Missing description

lib/gitlab/usage_data_counters/known_events/common.yml

@@ -440,3 +440,8 @@
   redis_slot: pipeline_authoring
   aggregation: weekly
   feature_flag: usage_data_unique_users_committing_ciconfigfile
+- name: o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile
+  category: pipeline_authoring
+  redis_slot: pipeline_authoring
+  aggregation: weekly
+  feature_flag: usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile

lib/gitlab/usage_data_counters/merge_request_activity_unique_counter.rb

@@ -41,6 +41,7 @@ module Gitlab
       MR_TIME_SPENT_CHANGED_ACTION = 'i_code_review_user_time_spent_changed'
       MR_ASSIGNEES_CHANGED_ACTION = 'i_code_review_user_assignees_changed'
       MR_REVIEWERS_CHANGED_ACTION = 'i_code_review_user_reviewers_changed'
+      MR_INCLUDING_CI_CONFIG_ACTION = 'o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile'
 
       class << self
         def track_mr_diffs_action(merge_request:)
@@ -183,6 +184,13 @@ module Gitlab
           track_unique_action_by_user(MR_REVIEWERS_CHANGED_ACTION, user)
         end
 
+        def track_mr_including_ci_config(user:, merge_request:)
+          return unless Feature.enabled?(:usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile, user, default_enabled: :yaml)
+          return unless merge_request.includes_ci_config?
+
+          track_unique_action_by_user(MR_INCLUDING_CI_CONFIG_ACTION, user)
+        end
+
         private
 
         def track_unique_action_by_merge_request(action, merge_request)

spec/lib/gitlab/usage_data_counters/merge_request_activity_unique_counter_spec.rb

@@ -21,6 +21,14 @@ RSpec.describe Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter, :cl
     end
   end
 
+  shared_examples_for 'not tracked merge request unique event' do
+    specify do
+      expect(Gitlab::UsageDataCounters::HLLRedisCounter).not_to receive(:track_event)
+
+      subject
+    end
+  end
+
   describe '.track_mr_diffs_action' do
     subject { described_class.track_mr_diffs_action(merge_request: merge_request) }
 
@@ -332,4 +340,34 @@ RSpec.describe Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter, :cl
       let(:action) { described_class::MR_REVIEWERS_CHANGED_ACTION }
     end
   end
+
+  describe '.track_mr_including_ci_config' do
+    subject { described_class.track_mr_including_ci_config(user: user, merge_request: merge_request) }
+
+    context 'when merge request includes a ci config change' do
+      before do
+        allow(merge_request).to receive(:diff_stats).and_return([double(path: 'abc.txt'), double(path: '.gitlab-ci.yml')])
+      end
+
+      it_behaves_like 'a tracked merge request unique event' do
+        let(:action) { described_class::MR_INCLUDING_CI_CONFIG_ACTION }
+      end
+
+      context 'when FF usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile is disabled' do
+        before do
+          stub_feature_flags(usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile: false)
+        end
+
+        it_behaves_like 'not tracked merge request unique event'
+      end
+    end
+
+    context 'when merge request does not include any ci config change' do
+      before do
+        allow(merge_request).to receive(:diff_stats).and_return([double(path: 'abc.txt'), double(path: 'abc.xyz')])
+      end
+
+      it_behaves_like 'not tracked merge request unique event'
+    end
+  end
 end

spec/lib/gitlab/usage_data_spec.rb

@@ -1353,7 +1353,7 @@ RSpec.describe Gitlab::UsageData, :aggregate_failures do
 
     let(:categories) { ::Gitlab::UsageDataCounters::HLLRedisCounter.categories }
     let(:ineligible_total_categories) do
-      %w[source_code ci_secrets_management incident_management_alerts snippets terraform pipeline_authoring]
+      %w[source_code ci_secrets_management incident_management_alerts snippets terraform]
     end
 
     it 'has all known_events' do

spec/models/merge_request_spec.rb

@@ -4856,4 +4856,33 @@ RSpec.describe MergeRequest, factory_default: :keep do
       end
     end
   end
+
+  describe '#includes_ci_config?' do
+    let(:merge_request) { build(:merge_request) }
+    let(:project) { merge_request.project }
+
+    subject(:result) { merge_request.includes_ci_config? }
+
+    before do
+      allow(merge_request).to receive(:diff_stats).and_return(diff_stats)
+    end
+
+    context 'when diff_stats is nil' do
+      let(:diff_stats) {}
+
+      it { is_expected.to eq(false) }
+    end
+
+    context 'when diff_stats does not include the ci config path of the project' do
+      let(:diff_stats) { [double(path: 'abc.txt')] }
+
+      it { is_expected.to eq(false) }
+    end
+
+    context 'when diff_stats includes the ci config path of the project' do
+      let(:diff_stats) { [double(path: '.gitlab-ci.yml')] }
+
+      it { is_expected.to eq(true) }
+    end
+  end
 end

spec/services/merge_requests/after_create_service_spec.rb

@@ -32,6 +32,10 @@ RSpec.describe MergeRequests::AfterCreateService do
         .to receive(:track_create_mr_action)
         .with(user: merge_request.author)
 
+      expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
+        .to receive(:track_mr_including_ci_config)
+        .with(user: merge_request.author, merge_request: merge_request)
+
       execute_service
     end
 

spec/services/merge_requests/refresh_service_spec.rb

@@ -170,6 +170,18 @@ RSpec.describe MergeRequests::RefreshService do
             .not_to change { @merge_request.reload.merge_request_diff }
         end
       end
+
+      it 'calls the merge request activity counter' do
+        expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
+          .to receive(:track_mr_including_ci_config)
+          .with(user: @merge_request.author, merge_request: @merge_request)
+
+        expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
+          .to receive(:track_mr_including_ci_config)
+          .with(user: @another_merge_request.author, merge_request: @another_merge_request)
+
+        refresh_service.execute(@oldrev, @newrev, 'refs/heads/master')
+      end
     end
 
     context 'when pipeline exists for the source branch' do