Move PrometheusMetric out of EE

PrometheusMetric is one of the dependencies of
the generic alerts endpoint feature, which is about to be moved to CE

app/models/prometheus_metric.rb

@@ -2,6 +2,7 @@
 
 class PrometheusMetric < ApplicationRecord
   belongs_to :project, validate: true, inverse_of: :prometheus_metrics
+  has_many :prometheus_alerts, inverse_of: :prometheus_metric
 
   enum group: PrometheusMetricEnums.groups
 
@@ -73,5 +74,3 @@ class PrometheusMetric < ApplicationRecord
     PrometheusMetricEnums.group_details.fetch(group.to_sym)
   end
 end
-
-PrometheusMetric.prepend_if_ee('EE::PrometheusMetric')

app/models/prometheus_metric_enums.rb

@@ -9,7 +9,8 @@ module PrometheusMetricEnums
       aws_elb: -3,
       nginx: -4,
       kubernetes: -5,
-      nginx_ingress: -6
+      nginx_ingress: -6,
+      cluster_health: -100
     }.merge(custom_groups).freeze
   end
 
@@ -54,6 +55,11 @@ module PrometheusMetricEnums
         group_title: _('System metrics (Kubernetes)'),
         required_metrics: %w(container_memory_usage_bytes container_cpu_usage_seconds_total),
         priority: 5
+      }.freeze,
+      cluster_health: {
+        group_title: _('Cluster Health'),
+        required_metrics: %w(container_memory_usage_bytes container_cpu_usage_seconds_total),
+        priority: 10
       }.freeze
     }.merge(custom_group_details).freeze
   end
@@ -76,5 +82,3 @@ module PrometheusMetricEnums
     }.freeze
   end
 end
-
-PrometheusMetricEnums.prepend_if_ee('EE::PrometheusMetricEnums')

ee/app/models/ee/prometheus_metric.rb

-# frozen_string_literal: true
-
-module EE
-  module PrometheusMetric
-    extend ActiveSupport::Concern
-    extend ::Gitlab::Utils::Override
-
-    prepended do
-      has_many :prometheus_alerts, inverse_of: :prometheus_metric
-    end
-  end
-end

ee/app/models/ee/prometheus_metric_enums.rb

-# frozen_string_literal: true
-
-module EE
-  module PrometheusMetricEnums
-    extend ActiveSupport::Concern
-
-    class_methods do
-      extend ::Gitlab::Utils::Override
-
-      override :groups
-      def groups
-        super.merge(
-          # Start at -100 to avoid collisions with CE values
-          # built-in groups
-          cluster_health: -100
-        )
-      end
-
-      override :group_details
-      def group_details
-        super.merge(
-          # keys can collide with CE values! please ensure you are not redefining a key that already exists in app/models/prometheus_metric_enums.rb#group_details
-          # built-in groups
-          cluster_health: {
-            group_title: _('Cluster Health'),
-            required_metrics: %w(container_memory_usage_bytes container_cpu_usage_seconds_total),
-            priority: 10
-          }
-        )
-      end
-    end
-  end
-end

ee/lib/ee/gitlab/database_importers/common_metrics/prometheus_metric_enums.rb

-# frozen_string_literal: true
-
-module EE
-  module Gitlab
-    module DatabaseImporters
-      module CommonMetrics
-        module PrometheusMetricEnums
-          extend ActiveSupport::Concern
-
-          class_methods do
-            extend ::Gitlab::Utils::Override
-
-            override :groups
-            def groups
-              super.merge(
-                # Start at 100 to avoid collisions with CE values
-                cluster_health: -100
-              )
-            end
-
-            override :group_titles
-            def group_titles
-              super.merge(
-                # keys can collide with CE values! please ensure you are not redefining a key that already exists
-                cluster_health: _('Cluster Health')
-              )
-            end
-          end
-        end
-      end
-    end
-  end
-end

ee/spec/models/prometheus_metric_spec.rb

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-describe PrometheusMetric do
-  subject { build(:prometheus_metric) }
-
-  describe '#group_title' do
-    shared_examples 'group_title' do |group, title|
-      subject { build(:prometheus_metric, group: group).group_title }
-
-      it "returns text #{title} for group #{group}" do
-        expect(subject).to eq(title)
-      end
-    end
-
-    it_behaves_like 'group_title', :cluster_health, 'Cluster Health'
-  end
-
-  describe '#priority' do
-    using RSpec::Parameterized::TableSyntax
-
-    where(:group, :priority) do
-      :cluster_health | 10
-    end
-
-    with_them do
-      before do
-        subject.group = group
-      end
-
-      it { expect(subject.priority).to eq(priority) }
-    end
-  end
-
-  describe '#required_metrics' do
-    using RSpec::Parameterized::TableSyntax
-
-    where(:group, :required_metrics) do
-      :cluster_health | %w(container_memory_usage_bytes container_cpu_usage_seconds_total)
-    end
-
-    with_them do
-      before do
-        subject.group = group
-      end
-
-      it { expect(subject.required_metrics).to eq(required_metrics) }
-    end
-  end
-end

lib/gitlab/database_importers/common_metrics.rb

@@ -6,5 +6,3 @@ module Gitlab
     end
   end
 end
-
-Gitlab::DatabaseImporters::CommonMetrics.prepend_if_ee('EE::Gitlab::DatabaseImporters::CommonMetrics')

lib/gitlab/database_importers/common_metrics/prometheus_metric_enums.rb

@@ -17,7 +17,9 @@ module Gitlab
             # custom groups
             business: 0,
             response: 1,
-            system: 2
+            system: 2,
+
+            cluster_health: -100
           }
         end
 
@@ -31,12 +33,11 @@ module Gitlab
             ha_proxy: _('Response metrics (HA Proxy)'),
             aws_elb: _('Response metrics (AWS ELB)'),
             nginx: _('Response metrics (NGINX)'),
-            kubernetes: _('System metrics (Kubernetes)')
+            kubernetes: _('System metrics (Kubernetes)'),
+            cluster_health: _('Cluster Health')
           }
         end
       end
     end
   end
 end
-
-::Gitlab::DatabaseImporters::CommonMetrics::PrometheusMetricEnums.prepend_if_ee('EE::Gitlab::DatabaseImporters::CommonMetrics::PrometheusMetricEnums')

spec/models/prometheus_metric_spec.rb

@@ -67,6 +67,7 @@ describe PrometheusMetric do
     it_behaves_like 'group_title', :business, 'Business metrics (Custom)'
     it_behaves_like 'group_title', :response, 'Response metrics (Custom)'
     it_behaves_like 'group_title', :system, 'System metrics (Custom)'
+    it_behaves_like 'group_title', :cluster_health, 'Cluster Health'
   end
 
   describe '#priority' do
@@ -82,6 +83,7 @@ describe PrometheusMetric do
       :business          | 0
       :response          | -5
       :system            | -10
+      :cluster_health    | 10
     end
 
     with_them do
@@ -106,6 +108,7 @@ describe PrometheusMetric do
       :business          | %w()
       :response          | %w()
       :system            | %w()
+      :cluster_health    | %w(container_memory_usage_bytes container_cpu_usage_seconds_total)
     end
 
     with_them do