New internal endpoint for kas to increment gitop_sync metric

This metric will then be pushed onto a Redis counter. The redis counter
will then be posted to usage ping later.

DRY up specs for common authorization problems

Add kubernetes_agent_gitops_sync to usage ping

changelogs/unreleased/agent_gitops_sync_count.yml

+---
+title: Add kubernetes_agent_gitops_sync usage ping metric
+merge_request: 40568
+author:
+type: other

lib/api/internal/kubernetes.rb

@@ -96,6 +96,25 @@ module API
               gitaly_repository: gitaly_repository(project)
             }
           end
+
+          desc 'POST usage metrics' do
+            detail 'Updates usage metrics for agent'
+          end
+          route_setting :authentication, cluster_agent_token_allowed: true
+          params do
+            requires :gitops_sync_count, type: Integer, desc: 'The count to increment the gitops_sync metric by'
+          end
+          post '/usage_metrics' do
+            gitops_sync_count = params[:gitops_sync_count]
+
+            if gitops_sync_count < 0
+              bad_request!('gitops_sync_count must be greater than or equal to zero')
+            else
+              Gitlab::UsageDataCounters::KubernetesAgentCounter.increment_gitops_sync(gitops_sync_count)
+
+              no_content!
+            end
+          end
         end
       end
     end

lib/gitlab/usage_data.rb

@@ -245,7 +245,8 @@ module Gitlab
           Gitlab::UsageDataCounters::ProductivityAnalyticsCounter,
           Gitlab::UsageDataCounters::SourceCodeCounter,
           Gitlab::UsageDataCounters::MergeRequestCounter,
-          Gitlab::UsageDataCounters::DesignsCounter
+          Gitlab::UsageDataCounters::DesignsCounter,
+          Gitlab::UsageDataCounters::KubernetesAgentCounter
         ]
       end
 

lib/gitlab/usage_data_counters/kubernetes_agent_counter.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module UsageDataCounters
+    class KubernetesAgentCounter < BaseCounter
+      PREFIX = 'kubernetes_agent'
+      KNOWN_EVENTS = %w[gitops_sync].freeze
+
+      class << self
+        def increment_gitops_sync(incr)
+          raise ArgumentError, 'must be greater than or equal to zero' if incr < 0
+
+          # rather then hitting redis for this no-op, we return early
+          # note: redis returns the increment, so we mimic this here
+          return 0 if incr == 0
+
+          increment_by(redis_key(:gitops_sync), incr)
+        end
+      end
+    end
+  end
+end

lib/gitlab/usage_data_counters/redis_counter.rb

@@ -9,6 +9,12 @@ module Gitlab
         Gitlab::Redis::SharedState.with { |redis| redis.incr(redis_counter_key) }
       end
 
+      def increment_by(redis_counter_key, incr)
+        return unless Gitlab::CurrentSettings.usage_ping_enabled
+
+        Gitlab::Redis::SharedState.with { |redis| redis.incrby(redis_counter_key, incr) }
+      end
+
       def total_count(redis_counter_key)
         Gitlab::Redis::SharedState.with { |redis| redis.get(redis_counter_key).to_i }
       end

spec/lib/gitlab/usage_data_counters/kubernetes_agent_counter_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::UsageDataCounters::KubernetesAgentCounter do
+  it_behaves_like 'a redis usage counter', 'Kubernetes Agent', :gitops_sync
+
+  it_behaves_like 'a redis usage counter with totals', :kubernetes_agent, gitops_sync: 1
+
+  describe '.increment_gitops_sync' do
+    it 'increments the gtops_sync counter by the new increment amount' do
+      described_class.increment_gitops_sync(7)
+      described_class.increment_gitops_sync(2)
+      described_class.increment_gitops_sync(0)
+
+      expect(described_class.totals).to eq(kubernetes_agent_gitops_sync: 9)
+    end
+
+    it 'raises for negative numbers' do
+      expect { described_class.increment_gitops_sync(-1) }.to raise_error(ArgumentError)
+    end
+  end
+end

spec/lib/gitlab/usage_data_counters/redis_counter_spec.rb

@@ -11,6 +11,7 @@ RSpec.describe Gitlab::UsageDataCounters::RedisCounter, :clean_gitlab_redis_shar
     stub_application_setting(usage_ping_enabled: setting_value)
   end
 
+  describe '.increment' do
     context 'when usage_ping is disabled' do
       let(:setting_value) { false }
 
@@ -30,4 +31,27 @@ RSpec.describe Gitlab::UsageDataCounters::RedisCounter, :clean_gitlab_redis_shar
         end.to change { subject.total_count(redis_key) }.by(1)
       end
     end
+  end
+
+  describe '.increment_by' do
+    context 'when usage_ping is disabled' do
+      let(:setting_value) { false }
+
+      it 'counter is not increased' do
+        expect do
+          subject.increment_by(redis_key, 3)
+        end.not_to change { subject.total_count(redis_key) }
+      end
+    end
+
+    context 'when usage_ping is enabled' do
+      let(:setting_value) { true }
+
+      it 'counter is increased' do
+        expect do
+          subject.increment_by(redis_key, 3)
+        end.to change { subject.total_count(redis_key) }.by(3)
+      end
+    end
+  end
 end

spec/lib/gitlab/usage_data_spec.rb

@@ -575,6 +575,12 @@ RSpec.describe Gitlab::UsageData, :aggregate_failures do
     end
   end
 
+  describe '.usage_counters' do
+    subject { described_class.usage_counters }
+
+    it { is_expected.to include(:kubernetes_agent_gitops_sync) }
+  end
+
   describe '.usage_data_counters' do
     subject { described_class.usage_data_counters }
 

spec/requests/api/internal/kubernetes_spec.rb

@@ -15,11 +15,7 @@ RSpec.describe API::Internal::Kubernetes do
     allow(Gitlab::Kas).to receive(:secret).and_return(jwt_secret)
   end
 
-  describe "GET /internal/kubernetes/agent_info" do
-    def send_request(headers: {}, params: {})
-      get api('/internal/kubernetes/agent_info'), params: params, headers: headers.reverse_merge(jwt_auth_headers)
-    end
-
+  shared_examples 'authorization' do
     context 'not authenticated' do
       it 'returns 401' do
         send_request(headers: { Gitlab::Kas::INTERNAL_API_REQUEST_HEADER => '' })
@@ -28,6 +24,20 @@ RSpec.describe API::Internal::Kubernetes do
       end
     end
 
+    context 'authenticated' do
+      it 'returns 403 if Authorization header not sent' do
+        send_request
+
+        expect(response).to have_gitlab_http_status(:forbidden)
+      end
+
+      it 'returns 404 if Authorization is for non-existent agent' do
+        send_request(headers: { 'Authorization' => 'Bearer NONEXISTENT' })
+
+        expect(response).to have_gitlab_http_status(:forbidden)
+      end
+    end
+
     context 'kubernetes_agent_internal_api feature flag disabled' do
       before do
         stub_feature_flags(kubernetes_agent_internal_api: false)
@@ -39,13 +49,51 @@ RSpec.describe API::Internal::Kubernetes do
         expect(response).to have_gitlab_http_status(:not_found)
       end
     end
+  end
 
-    it 'returns 403 if Authorization header not sent' do
-      send_request
+  describe 'POST /internal/kubernetes/usage_metrics' do
+    def send_request(headers: {}, params: {})
+      post api('/internal/kubernetes/usage_metrics'), params: params, headers: headers.reverse_merge(jwt_auth_headers)
+    end
 
-      expect(response).to have_gitlab_http_status(:forbidden)
+    include_examples 'authorization'
+
+    context 'is authenticated for an agent' do
+      let!(:agent_token) { create(:cluster_agent_token) }
+
+      it 'returns no_content for valid gitops_sync_count' do
+        send_request(params: { gitops_sync_count: 10 }, headers: { 'Authorization' => "Bearer #{agent_token.token}" })
+
+        expect(response).to have_gitlab_http_status(:no_content)
+      end
+
+      it 'returns no_content 0 gitops_sync_count' do
+        send_request(params: { gitops_sync_count: 0 }, headers: { 'Authorization' => "Bearer #{agent_token.token}" })
+
+        expect(response).to have_gitlab_http_status(:no_content)
+      end
+
+      it 'returns 400 for non number' do
+        send_request(params: { gitops_sync_count: 'string' }, headers: { 'Authorization' => "Bearer #{agent_token.token}" })
+
+        expect(response).to have_gitlab_http_status(:bad_request)
+      end
+
+      it 'returns 400 for negative number' do
+        send_request(params: { gitops_sync_count: '-1' }, headers: { 'Authorization' => "Bearer #{agent_token.token}" })
+
+        expect(response).to have_gitlab_http_status(:bad_request)
+      end
+    end
+  end
+
+  describe "GET /internal/kubernetes/agent_info" do
+    def send_request(headers: {}, params: {})
+      get api('/internal/kubernetes/agent_info'), params: params, headers: headers.reverse_merge(jwt_auth_headers)
     end
 
+    include_examples 'authorization'
+
     context 'an agent is found' do
       let!(:agent_token) { create(:cluster_agent_token) }
 
@@ -77,14 +125,6 @@ RSpec.describe API::Internal::Kubernetes do
         )
       end
     end
-
-    context 'no such agent exists' do
-      it 'returns 404' do
-        send_request(headers: { 'Authorization' => 'Bearer ABCD' })
-
-        expect(response).to have_gitlab_http_status(:forbidden)
-      end
-    end
   end
 
   describe 'GET /internal/kubernetes/project_info' do
@@ -92,39 +132,7 @@ RSpec.describe API::Internal::Kubernetes do
       get api('/internal/kubernetes/project_info'), params: params, headers: headers.reverse_merge(jwt_auth_headers)
     end
 
-    context 'not authenticated' do
-      it 'returns 401' do
-        send_request(headers: { Gitlab::Kas::INTERNAL_API_REQUEST_HEADER => '' })
-
-        expect(response).to have_gitlab_http_status(:unauthorized)
-      end
-    end
-
-    context 'kubernetes_agent_internal_api feature flag disabled' do
-      before do
-        stub_feature_flags(kubernetes_agent_internal_api: false)
-      end
-
-      it 'returns 404' do
-        send_request
-
-        expect(response).to have_gitlab_http_status(:not_found)
-      end
-    end
-
-    it 'returns 403 if Authorization header not sent' do
-      send_request
-
-      expect(response).to have_gitlab_http_status(:forbidden)
-    end
-
-    context 'no such agent exists' do
-      it 'returns 404' do
-        send_request(headers: { 'Authorization' => 'Bearer ABCD' })
-
-        expect(response).to have_gitlab_http_status(:forbidden)
-      end
-    end
+    include_examples 'authorization'
 
     context 'an agent is found' do
       let!(:agent_token) { create(:cluster_agent_token) }