Add a metric to track usage of the new Export Payload button

Redis count metric is added

app/controllers/admin/application_settings_controller.rb

@@ -66,7 +66,12 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
 
         render html: Gitlab::Highlight.highlight('payload.json', usage_data_json, language: 'json')
       end
-      format.json { render json: Gitlab::Usage::ServicePingReport.for(output: :all_metrics_values, cached: true).to_json }
+
+      format.json do
+        Gitlab::UsageDataCounters::ServiceUsageDataCounter.count(:download_payload_click)
+
+        render json: Gitlab::Usage::ServicePingReport.for(output: :all_metrics_values, cached: true).to_json
+      end
     end
   end
 

config/metrics/counts_all/20220314362302_service_usage_data_download_payload.yml

+---
+key_path: counts.service_usage_data_download_payload_click
+description: Count Download Payload button clicks
+data_category: optional
+name: count_promoted_issues
+product_section: growth
+product_stage: growth
+product_group: group::product intelligence
+product_category: collection
+value_type: number
+status: active
+time_frame: all
+data_source: redis
+distribution:
+  - ce
+  - ee
+tier:
+  - free
+  - premium
+  - ultimate
+performance_indicator_type: []
+milestone: "14.9"

lib/gitlab/usage_data_counters.rb

@@ -16,7 +16,8 @@ module Gitlab
       DesignsCounter,
       KubernetesAgentCounter,
       StaticSiteEditorCounter,
-      DiffsCounter
+      DiffsCounter,
+      ServiceUsageDataCounter
     ].freeze
 
     UsageDataCounterError = Class.new(StandardError)

lib/gitlab/usage_data_counters/service_usage_data_counter.rb

+# frozen_string_literal: true
+
+module Gitlab::UsageDataCounters
+  class ServiceUsageDataCounter < BaseCounter
+    KNOWN_EVENTS = %w[download_payload_click].freeze
+    PREFIX = 'service_usage_data'
+  end
+end

spec/controllers/admin/application_settings_controller_spec.rb

@@ -81,6 +81,18 @@ RSpec.describe Admin::ApplicationSettingsController, :do_not_mock_admin_mode_set
       expect(body).to include('counts')
       expect(response).to have_gitlab_http_status(:ok)
     end
+
+    describe 'usage data counter' do
+      let(:counter) { Gitlab::UsageDataCounters::ServiceUsageDataCounter }
+
+      it 'incremented when json generated' do
+        expect { get :usage_data, format: :json }.to change { counter.read(:download_payload_click) }.by(1)
+      end
+
+      it 'not incremented when html format requested' do
+        expect { get :usage_data }.not_to change { counter.read(:download_payload_click) }
+      end
+    end
   end
 
   describe 'PUT #update' do

spec/lib/gitlab/usage_data_counters/service_usage_data_counter_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::UsageDataCounters::ServiceUsageDataCounter do
+  it_behaves_like 'a redis usage counter', 'Service Usage Data', :download_payload_click
+end

spec/support/helpers/usage_data_helpers.rb

@@ -129,6 +129,7 @@ module UsageDataHelpers
       uploads
       web_hooks
       user_preferences_user_gitpod_enabled
+      service_usage_data_download_payload_click
     ).push(*SMAU_KEYS)
 
   USAGE_DATA_KEYS = %i(