Merge branch '235459-add-usage-data-tracking-for-ui-events' into 'master'

Add Usage data tracking using Redis HLL for UI events

See merge request gitlab-org/gitlab!41301

config/feature_flags/development/usage_data_api.yml

+---
+name: usage_data_api
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41301
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/235459
+group: group::telemetry
+type: development
+default_enabled: false

doc/development/telemetry/usage_ping.md

@@ -312,6 +312,28 @@ Implemented using Redis methods [PFADD](https://redis.io/commands/pfadd) and [PF
    end
    ```
 
+1. Track event using `UsageData` API
+
+   Increment unique users count using Redis HLL, for given event name.
+
+   In order to be able to increment the values the related feature `usage_data<event_name>` should be enabled.
+
+   ```plaintext
+   POST /usage_data/increment_unique_users
+   ```
+
+   | Attribute | Type | Required | Description |
+   | :-------- | :--- | :------- | :---------- |
+   | `event` | string | yes | The event name it should be tracked |
+
+   Response
+
+   Return 200 if tracking failed for any reason.
+
+   - `401 Unauthorized` if user is not authenticated
+   - `400 Bad request` if event parameter is missing
+   - `200` if event was tracked or any errors
+
 1. Track event using base module `Gitlab::UsageDataCounters::HLLRedisCounter.track_event(entity_id, event_name)`.
 
    Arguments:

lib/api/api.rb

@@ -235,6 +235,7 @@ module API
       mount ::API::Templates
       mount ::API::Todos
       mount ::API::Triggers
+      mount ::API::UsageData
       mount ::API::UserCounts
       mount ::API::Users
       mount ::API::Variables

lib/api/usage_data.rb

+# frozen_string_literal: true
+
+module API
+  class UsageData < Grape::API::Instance
+    before { authenticate! }
+
+    namespace 'usage_data' do
+      before do
+        not_found! unless Feature.enabled?(:usage_data_api)
+      end
+
+      desc 'Track usage data events' do
+        detail 'This feature was introduced in GitLab 13.4.'
+      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]
+
+        increment_unique_values(event_name, current_user.id)
+
+        status :ok
+      end
+    end
+  end
+end

spec/requests/api/usage_data_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe API::UsageData do
+  let_it_be(:user) { create(:user) }
+
+  describe 'POST /usage_data/increment_unique_users' do
+    let(:endpoint) { '/usage_data/increment_unique_users' }
+    let(:known_event) { 'g_compliance_dashboard' }
+    let(:unknown_event) { 'unknown' }
+
+    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)
+      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
+
+      context 'with correct params' do
+        it 'returns status ok' do
+          expect(Gitlab::Redis::HLL).to receive(:add)
+
+          post api(endpoint, user), params: { event: known_event }
+
+          expect(response).to have_gitlab_http_status(:ok)
+        end
+      end
+
+      context 'with unknown event' do
+        it 'returns status ok' do
+          expect(Gitlab::Redis::HLL).not_to receive(:add)
+
+          post api(endpoint, user), params: { event: unknown_event }
+
+          expect(response).to have_gitlab_http_status(:ok)
+        end
+      end
+    end
+  end
+end