Include pod log usage in the usage ping

Adds tracking for pod logs usage on a per-project basis. We want
to be able to determine how the usage of the feature is changing
over time.

ee/app/controllers/ee/projects/environments_controller.rb

@@ -15,6 +15,7 @@ module EE
         respond_to do |format|
           format.html
           format.json do
+            ::Gitlab::PodLogsUsageCounter.increment(project.id)
             ::Gitlab::PollingInterval.set_header(response, interval: 3_000)
 
             render json: {

ee/changelogs/unreleased/report-log-usage.yml

+---
+title: Collect usage of pod logs feature
+merge_request: 10370
+author:
+type: added

ee/lib/ee/gitlab/usage_data.rb

@@ -132,6 +132,13 @@ module EE
           usage_data
         end
 
+        override :usage_counters
+        def usage_counters
+          super.merge(
+            pod_logs_usages: ::Gitlab::PodLogsUsageCounter.usage_totals
+          )
+        end
+
         override :jira_usage
         def jira_usage
           super.merge(

ee/lib/gitlab/pod_logs_usage_counter.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module PodLogsUsageCounter
+    BASE_KEY = "POD_LOGS_USAGE_COUNTS"
+
+    class << self
+      def increment(project_id)
+        Gitlab::Redis::SharedState.with { |redis| redis.hincrby(BASE_KEY, project_id, 1) }
+      end
+
+      def usage_totals
+        Gitlab::Redis::SharedState.with do |redis|
+          total_sum = 0
+
+          totals = redis.hgetall(BASE_KEY).each_with_object({}) do |(project_id, count), result|
+            total_sum += result[project_id.to_i] = count.to_i
+          end
+
+          totals[:total] = total_sum
+          totals
+        end
+      end
+    end
+  end
+end

ee/spec/controllers/projects/environments_controller_spec.rb

@@ -117,6 +117,12 @@ describe Projects::EnvironmentsController do
         expect(json_response["logs"]).to match_array(["Log 1", "Log 2", "Log 3"])
         expect(json_response["pods"]).to match_array([pod_name])
       end
+
+      it 'registers a usage of the endpoint' do
+        expect(::Gitlab::PodLogsUsageCounter).to receive(:increment).with(project.id)
+
+        get :logs, params: environment_params(pod_name: pod_name, format: :json)
+      end
     end
   end
 

ee/spec/lib/gitlab/pod_logs_usage_counter_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::PodLogsUsageCounter, :clean_gitlab_redis_shared_state do
+  describe '.increment' do
+    it 'intializes and increments the counter for the project by 1' do
+      expect do
+        described_class.increment(12)
+      end.to change { described_class.usage_totals[12] }.from(nil).to(1)
+    end
+  end
+
+  describe '.usage_totals' do
+    context 'when the feature has not been used' do
+      it 'returns the total counts and counts per project' do
+        expect(described_class.usage_totals.keys).to eq([:total])
+        expect(described_class.usage_totals[:total]).to eq(0)
+      end
+    end
+
+    context 'when the feature has been used in multiple projects' do
+      before do
+        described_class.increment(12)
+        described_class.increment(16)
+      end
+
+      it 'returns the total counts and counts per project' do
+        expect(described_class.usage_totals[12]).to eq(1)
+        expect(described_class.usage_totals[16]).to eq(1)
+        expect(described_class.usage_totals[:total]).to eq(2)
+      end
+    end
+  end
+end

ee/spec/lib/gitlab/usage_data_spec.rb

@@ -52,6 +52,7 @@ describe Gitlab::UsageData do
         license_id
         elasticsearch_enabled
         geo_enabled
+        pod_logs_usages
       ))
     end