Add `increment_counter` to Usage Ping API

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/233994

**Problem**

There is no API endpoint that can process ordinary Redis counter
events.

**Solution**

Add `increment_counter` endpoint to accept ordinary Redis events.

changelogs/unreleased/233994_extend_usage_ping_api.yml

+---
+title: Add `increment_counter` to Usage Ping API
+merge_request: 47309
+author:
+type: added

config/feature_flags/development/usage_data_static_site_editor_commits.yml

+---
+name: usage_data_static_site_editor_commits
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/47309
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/284082
+milestone: '13.6'
+type: development
+group: group::static_site_editor
+default_enabled: false

config/feature_flags/development/usage_data_static_site_editor_merge_requests.yml

+---
+name: usage_data_static_site_editor_merge_requests
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/47309
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/284083
+milestone: '13.6'
+type: development
+group: group::static_site_editor
+default_enabled: false

lib/api/helpers.rb

@@ -536,6 +536,15 @@ module API
       )
     end
 
+    def increment_counter(event_name)
+      feature_name = "usage_data_#{event_name}"
+      return unless Feature.enabled?(feature_name)
+
+      Gitlab::UsageDataCounters.count(event_name)
+    rescue => error
+      Gitlab::AppLogger.warn("Redis tracking event failed for event: #{event_name}, message: #{error.message}")
+    end
+
     # @param event_name [String] the event name
     # @param values [Array|String] the values counted
     def increment_unique_values(event_name, values)

lib/api/usage_data.rb

@@ -20,6 +20,18 @@ module API
         requires :event, type: String, desc: 'The event name that should be tracked'
       end
 
+      post 'increment_counter' do
+        event_name = params[:event]
+
+        increment_counter(event_name)
+
+        status :ok
+      end
+
+      params do
+        requires :event, type: String, desc: 'The event name that should be tracked'
+      end
+
       post 'increment_unique_users' do
         event_name = params[:event]
 

lib/gitlab/usage_data.rb

@@ -296,20 +296,7 @@ module Gitlab
 
       # @return [Array<#totals>] An array of objects that respond to `#totals`
       def usage_data_counters
-        [
-          Gitlab::UsageDataCounters::WikiPageCounter,
-          Gitlab::UsageDataCounters::WebIdeCounter,
-          Gitlab::UsageDataCounters::NoteCounter,
-          Gitlab::UsageDataCounters::SnippetCounter,
-          Gitlab::UsageDataCounters::SearchCounter,
-          Gitlab::UsageDataCounters::CycleAnalyticsCounter,
-          Gitlab::UsageDataCounters::ProductivityAnalyticsCounter,
-          Gitlab::UsageDataCounters::SourceCodeCounter,
-          Gitlab::UsageDataCounters::MergeRequestCounter,
-          Gitlab::UsageDataCounters::DesignsCounter,
-          Gitlab::UsageDataCounters::KubernetesAgentCounter,
-          Gitlab::UsageDataCounters::StaticSiteEditorCounter
-        ]
+        Gitlab::UsageDataCounters.counters
       end
 
       def components_usage_data

lib/gitlab/usage_data_counters.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module UsageDataCounters
+    COUNTERS = [
+      WikiPageCounter,
+      WebIdeCounter,
+      NoteCounter,
+      SnippetCounter,
+      SearchCounter,
+      CycleAnalyticsCounter,
+      ProductivityAnalyticsCounter,
+      SourceCodeCounter,
+      MergeRequestCounter,
+      DesignsCounter,
+      KubernetesAgentCounter,
+      StaticSiteEditorCounter
+    ].freeze
+
+    UsageDataCounterError = Class.new(StandardError)
+    UnknownEvent = Class.new(UsageDataCounterError)
+
+    class << self
+      def counters
+        self::COUNTERS
+      end
+
+      def count(event_name)
+        counters.each do |counter|
+          event = counter.fetch_supported_event(event_name)
+
+          return counter.count(event) if event
+        end
+
+        raise UnknownEvent, "Cannot find counter for event #{event_name}"
+      end
+    end
+  end
+end

lib/gitlab/usage_data_counters/base_counter.rb

@@ -29,6 +29,12 @@ module Gitlab::UsageDataCounters
         known_events.map { |event| [counter_key(event), -1] }.to_h
       end
 
+      def fetch_supported_event(event_name)
+        return if prefix.present? && !event_name.start_with?(prefix)
+
+        known_events.find { |event| counter_key(event) == event_name.to_sym }
+      end
+
       private
 
       def require_known_event(event)

lib/gitlab/usage_data_counters/search_counter.rb

@@ -4,6 +4,7 @@ module Gitlab
   module UsageDataCounters
     class SearchCounter < BaseCounter
       KNOWN_EVENTS = %w[all_searches navbar_searches].freeze
+      PREFIX = nil
 
       class << self
         def redis_key(event)

rubocop/rubocop-usage-data.yml

@@ -20,6 +20,7 @@ UsageData/LargeTable:
     - :Gitlab::Runtime
     - :Gitaly::Server
     - :Gitlab::UsageData
+    - :Gitlab::UsageDataCounters
     - :License
     - :Rails
     - :Time

spec/lib/gitlab/usage_data_counters/base_counter_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::UsageDataCounters::BaseCounter do
+  describe '.fetch_supported_event' do
+    subject { described_class.fetch_supported_event(event_name) }
+
+    let(:event_name) { 'generic_event' }
+    let(:prefix) { 'generic' }
+    let(:known_events) { %w[event another_event] }
+
+    before do
+      allow(described_class).to receive(:prefix) { prefix }
+      allow(described_class).to receive(:known_events) { known_events }
+    end
+
+    it 'returns the matching event' do
+      is_expected.to eq 'event'
+    end
+
+    context 'when event is unknown' do
+      let(:event_name) { 'generic_unknown_event' }
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'when prefix does not match the event name' do
+      let(:prefix) { 'special' }
+
+      it { is_expected.to be_nil }
+    end
+  end
+end

spec/lib/gitlab/usage_data_counters/search_counter_spec.rb

@@ -20,4 +20,12 @@ RSpec.describe Gitlab::UsageDataCounters::SearchCounter, :clean_gitlab_redis_sha
   context 'navbar_searches counter' do
     it_behaves_like 'usage counter with totals', :navbar_searches
   end
+
+  describe '.fetch_supported_event' do
+    subject { described_class.fetch_supported_event(event_name) }
+
+    let(:event_name) { 'all_searches' }
+
+    it { is_expected.to eq 'all_searches' }
+  end
 end

spec/lib/gitlab/usage_data_counters_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::UsageDataCounters do
+  describe '.usage_data_counters' do
+    subject { described_class.counters }
+
+    it { is_expected.to all(respond_to :totals) }
+    it { is_expected.to all(respond_to :fallback_totals) }
+  end
+
+  describe '.count' do
+    subject { described_class.count(event_name) }
+
+    let(:event_name) { 'static_site_editor_views' }
+
+    it 'increases a view counter' do
+      expect(Gitlab::UsageDataCounters::StaticSiteEditorCounter).to receive(:count).with('views')
+
+      subject
+    end
+
+    context 'when event_name is not defined' do
+      let(:event_name) { 'unknown' }
+
+      it 'raises an exception' do
+        expect { subject }.to raise_error(Gitlab::UsageDataCounters::UnknownEvent)
+      end
+    end
+  end
+end

spec/requests/api/usage_data_spec.rb

@@ -5,6 +5,87 @@ require 'spec_helper'
 RSpec.describe API::UsageData do
   let_it_be(:user) { create(:user) }
 
+  describe 'POST /usage_data/increment_counter' do
+    let(:endpoint) { '/usage_data/increment_counter' }
+    let(:known_event) { "#{known_event_prefix}_#{known_event_postfix}" }
+    let(:known_event_prefix) { "static_site_editor" }
+    let(:known_event_postfix) { 'commits' }
+    let(:unknown_event) { 'unknown' }
+
+    context 'without CSRF token' do
+      it 'returns forbidden' do
+        stub_feature_flags(usage_data_api: true)
+        allow(Gitlab::RequestForgeryProtection).to receive(:verified?).and_return(false)
+
+        post api(endpoint, user), params: { event: known_event }
+
+        expect(response).to have_gitlab_http_status(:forbidden)
+      end
+    end
+
+    context 'usage_data_api feature not enabled' do
+      it 'returns not_found' do
+        stub_feature_flags(usage_data_api: false)
+
+        post api(endpoint, user), params: { event: known_event }
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+
+    context 'without authentication' do
+      it 'returns 401 response' do
+        post api(endpoint), params: { event: known_event }
+
+        expect(response).to have_gitlab_http_status(:unauthorized)
+      end
+    end
+
+    context 'with authentication' do
+      before do
+        stub_feature_flags(usage_data_api: true)
+        stub_feature_flags("usage_data_#{known_event}" => true)
+        stub_application_setting(usage_ping_enabled: true)
+        allow(Gitlab::RequestForgeryProtection).to receive(:verified?).and_return(true)
+      end
+
+      context 'when event is missing from params' do
+        it 'returns bad request' do
+          post api(endpoint, user), params: {}
+
+          expect(response).to have_gitlab_http_status(:bad_request)
+        end
+      end
+
+      %w[merge_requests commits].each do |postfix|
+        context 'with correct params' do
+          let(:known_event_postfix) { postfix }
+
+          it 'returns status ok' do
+            expect(Gitlab::UsageDataCounters::BaseCounter).to receive(:count).with(known_event_postfix)
+            post api(endpoint, user), params: { event: known_event }
+
+            expect(response).to have_gitlab_http_status(:ok)
+          end
+        end
+      end
+
+      context 'with unknown event' do
+        before do
+          skip_feature_flags_yaml_validation
+        end
+
+        it 'returns status ok' do
+          expect(Gitlab::UsageDataCounters::BaseCounter).not_to receive(:count)
+
+          post api(endpoint, user), params: { event: unknown_event }
+
+          expect(response).to have_gitlab_http_status(:ok)
+        end
+      end
+    end
+  end
+
   describe 'POST /usage_data/increment_unique_users' do
     let(:endpoint) { '/usage_data/increment_unique_users' }
     let(:known_event) { 'g_compliance_dashboard' }