Provide metrics dashboards path to cluster charts

This makes it so we provide `dashboard-endpoint` to cluster health
charts. This is needed so the frontend knows where to fetch cluster
dashboards.

ee/app/controllers/ee/clusters/clusters_controller.rb

@@ -27,7 +27,7 @@ module EE
 
       def prometheus_proxy
         result = ::Prometheus::ProxyService.new(
-          clusterable.clusterable,
+          cluster.cluster,
           proxy_method,
           proxy_path,
           proxy_params

ee/app/helpers/ee/clusters_helper.rb

@@ -17,6 +17,7 @@ module EE
       {
         'clusters-path': clusterable.index_path,
         'metrics-endpoint': clusterable.metrics_cluster_path(cluster, format: :json),
+        'dashboard-endpoint': clusterable.metrics_dashboard_path(cluster),
         'documentation-path': help_page_path('administration/monitoring/prometheus/index.md'),
         'empty-getting-started-svg-path': image_path('illustrations/monitoring/getting_started.svg'),
         'empty-loading-svg-path': image_path('illustrations/monitoring/loading.svg'),

ee/app/presenters/ee/clusterable_presenter.rb

@@ -8,6 +8,10 @@ module EE
       raise NotImplementedError
     end
 
+    def metrics_dashboard_path(cluster)
+      raise NotImplementedError
+    end
+
     private
 
     override :multiple_clusters_available?

ee/app/presenters/ee/group_clusterable_presenter.rb

@@ -16,6 +16,11 @@ module EE
       environments_group_cluster_path(clusterable, cluster)
     end
 
+    override :metrics_dashboard_path
+    def metrics_dashboard_path(cluster)
+      metrics_dashboard_group_cluster_path(clusterable, cluster)
+    end
+
     private
 
     def can_read_cluster_environments?

ee/app/presenters/ee/instance_clusterable_presenter.rb

@@ -8,5 +8,10 @@ module EE
     def metrics_cluster_path(cluster, params = {})
       metrics_admin_cluster_path(cluster, params)
     end
+
+    override :metrics_dashboard_path
+    def metrics_dashboard_path(cluster)
+      metrics_dashboard_admin_cluster_path(cluster)
+    end
   end
 end

ee/app/presenters/ee/project_clusterable_presenter.rb

@@ -8,5 +8,10 @@ module EE
     def metrics_cluster_path(cluster, params = {})
       metrics_project_cluster_path(clusterable, cluster, params)
     end
+
+    override :metrics_dashboard_path
+    def metrics_dashboard_path(cluster)
+      metrics_dashboard_project_cluster_path(clusterable, cluster)
+    end
   end
 end

ee/spec/helpers/ee/clusters_helper_spec.rb

@@ -78,6 +78,7 @@ describe ClustersHelper do
         is_expected.to match(
           'clusters-path': clusterable_presenter.index_path,
           'metrics-endpoint': clusterable_presenter.metrics_cluster_path(cluster, format: :json),
+          'dashboard-endpoint': clusterable_presenter.metrics_dashboard_path(cluster),
           'documentation-path': help_page_path('administration/monitoring/prometheus/index.md'),
           'empty-getting-started-svg-path': match_asset_path('/assets/illustrations/monitoring/getting_started.svg'),
           'empty-loading-svg-path': match_asset_path('/assets/illustrations/monitoring/loading.svg'),

ee/spec/presenters/ee/instance_clusterable_presenter_spec.rb

@@ -14,4 +14,10 @@ describe InstanceClusterablePresenter do
 
     it { is_expected.to eq(metrics_admin_cluster_path(cluster)) }
   end
+
+  describe '#metrics_dashboard_path' do
+    subject { presenter.metrics_dashboard_path(cluster) }
+
+    it { is_expected.to eq(metrics_dashboard_admin_cluster_path(cluster)) }
+  end
 end

ee/spec/presenters/group_clusterable_presenter_spec.rb

@@ -40,4 +40,10 @@ describe GroupClusterablePresenter do
       it { is_expected.to be_nil }
     end
   end
+
+  describe '#metrics_dashboard_path' do
+    subject { presenter.metrics_dashboard_path(cluster) }
+
+    it { is_expected.to eq(metrics_dashboard_group_cluster_path(group, cluster)) }
+  end
 end

ee/spec/presenters/project_clusterable_presenter_spec.rb

@@ -14,4 +14,10 @@ describe ProjectClusterablePresenter do
 
     it { is_expected.to eq(metrics_project_cluster_path(project, cluster)) }
   end
+
+  describe '#metrics_dashboard_path' do
+    subject { presenter.metrics_dashboard_path(cluster) }
+
+    it { is_expected.to eq(metrics_dashboard_project_cluster_path(project, cluster)) }
+  end
 end

ee/spec/support/shared_examples/controllers/cluster_metrics_examples.rb

@@ -95,7 +95,7 @@ shared_examples 'cluster metrics' do
     context 'with valid requests' do
       before do
         allow(Prometheus::ProxyService).to receive(:new)
-          .with(clusterable, 'GET', 'query', expected_params)
+          .with(cluster, 'GET', 'query', expected_params)
           .and_return(prometheus_proxy_service)
 
         allow(prometheus_proxy_service).to receive(:execute)
@@ -112,7 +112,7 @@ shared_examples 'cluster metrics' do
           get :prometheus_proxy, params: prometheus_proxy_params
 
           expect(Prometheus::ProxyService).to have_received(:new)
-            .with(clusterable, 'GET', 'query', expected_params)
+            .with(cluster, 'GET', 'query', expected_params)
           expect(response).to have_gitlab_http_status(:ok)
           expect(json_response).to eq(prometheus_json_body)
         end