Implement PrometheusDeploymentLocator + fix metrics controller

app/controllers/projects/prometheus/metrics_controller.rb

 module Projects
   module Prometheus
     class MetricsController < Projects::ApplicationController
+      include PrometheusAdapterLocator
+
       before_action :authorize_admin_project!
       before_action :require_prometheus_metrics!
 
@@ -20,10 +22,6 @@ module Projects
 
       private
 
-      def prometheus_adapter
-        project.prometheus_service
-      end
-
       def require_prometheus_metrics!
         render_404 unless prometheus_adapter.can_query?
       end

app/models/concerns/prometheus_adapter_locator.rb

+module PrometheusAdapterLocator
+  def deployment_platform
+    project.deployment_platform
+  end
+
+  def prometheus_adapter
+    @prometheus_adapter ||= if service_prometheus_adapter.can_query?
+                              service_prometheus_adapter
+                            else
+                              cluster_prometheus_adapter
+                            end
+  end
+
+  def service_prometheus_adapter
+    project.find_or_initialize_service('prometheus')
+  end
+
+  def cluster_prometheus_adapter
+    return unless deployment_platform.respond_to?(:cluster)
+
+    cluster = deployment_platform.cluster
+    return unless cluster.application_prometheus&.installed?
+
+    cluster.application_prometheus
+  end
+end
\ No newline at end of file

app/models/environment.rb

 class Environment < ActiveRecord::Base
+  include PrometheusAdapterLocator
+
   # Used to generate random suffixes for the slug
   LETTERS = 'a'..'z'
   NUMBERS = '0'..'9'
@@ -224,27 +226,6 @@ class Environment < ActiveRecord::Base
     project.deployment_platform
   end
 
-  def prometheus_adapter
-    @prometheus_adapter ||= if service_prometheus_adapter.can_query?
-                              service_prometheus_adapter
-                            else
-                              cluster_prometheus_adapter
-                            end
-  end
-
-  def service_prometheus_adapter
-    project.find_or_initialize_service('prometheus')
-  end
-
-  def cluster_prometheus_adapter
-    return unless deployment_platform.respond_to?(:cluster)
-
-    cluster = deployment_platform.cluster
-    return unless cluster.application_prometheus&.installed?
-
-    cluster.application_prometheus
-  end
-
   private
 
   # Slugifying a name may remove the uniqueness guarantee afforded by it being

spec/controllers/projects/prometheus/metrics_controller_spec.rb

@@ -7,8 +7,7 @@ describe Projects::Prometheus::MetricsController do
   let(:prometheus_adapter) { double('prometheus_adapter', can_query?: true) }
 
   before do
-    allow(controller).to receive(:project).and_return(project)
-    allow(project).to receive(:prometheus_service).and_return(prometheus_adapter)
+    allow(controller).to receive(:prometheus_adapter).and_return(prometheus_adapter)
 
     project.add_master(user)
     sign_in(user)