Make external_dashboard_url available to frontend

- On Operations settings page
- On Metrics dashboard page

app/helpers/environments_helper.rb

@@ -30,7 +30,8 @@ module EnvironmentsHelper
       "environments-endpoint": project_environments_path(project, format: :json),
       "project-path" => project_path(project),
       "tags-path" => project_tags_path(project),
-      "has-metrics" => "#{environment.has_metrics?}"
+      "has-metrics" => "#{environment.has_metrics?}",
+      "external-dashboard-url" => project.metrics_setting_external_dashboard_url
     }
   end
 end

app/helpers/projects_helper.rb

@@ -343,6 +343,10 @@ module ProjectsHelper
     description.html_safe % { project_name: project.name }
   end
 
+  def metrics_external_dashboard_url
+    @project.metrics_setting_external_dashboard_url
+  end
+
   private
 
   def get_project_nav_tabs(project, current_user)

app/models/project.rb

@@ -309,6 +309,7 @@ class Project < ApplicationRecord
   delegate :group_clusters_enabled?, to: :group, allow_nil: true
   delegate :root_ancestor, to: :namespace, allow_nil: true
   delegate :last_pipeline, to: :commit, allow_nil: true
+  delegate :external_dashboard_url, to: :metrics_setting, allow_nil: true, prefix: true
 
   # Validations
   validates :creator, presence: true, on: :create

app/views/projects/settings/operations/_external_dashboard.html.haml

-.js-operation-settings{ data: { external_dashboard: { path: '',
+.js-operation-settings{ data: { external_dashboard: { path: metrics_external_dashboard_url,
   help_page_path: help_page_path('user/project/operations/link_to_external_dashboard') } } }

spec/helpers/environments_helper_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe EnvironmentsHelper do
+  set(:environment) { create(:environment) }
+  set(:project) { environment.project }
+  set(:user) { create(:user) }
+
+  describe '#metrics_data' do
+    before do
+      # This is so that this spec also passes in EE.
+      allow(helper).to receive(:current_user).and_return(user)
+      allow(helper).to receive(:can?).and_return(true)
+    end
+
+    let(:metrics_data) { helper.metrics_data(project, environment) }
+
+    it 'returns data' do
+      expect(metrics_data).to include(
+        'settings-path' => edit_project_service_path(project, 'prometheus'),
+        'clusters-path' => project_clusters_path(project),
+        'current-environment-name': environment.name,
+        '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'),
+        'empty-no-data-svg-path' => match_asset_path('/assets/illustrations/monitoring/no_data.svg'),
+        'empty-unable-to-connect-svg-path' => match_asset_path('/assets/illustrations/monitoring/unable_to_connect.svg'),
+        'metrics-endpoint' => additional_metrics_project_environment_path(project, environment, format: :json),
+        'deployment-endpoint' => project_environment_deployments_path(project, environment, format: :json),
+        'environments-endpoint': project_environments_path(project, format: :json),
+        'project-path' => project_path(project),
+        'tags-path' => project_tags_path(project),
+        'has-metrics' => "#{environment.has_metrics?}",
+        'external-dashboard-url' => nil
+      )
+    end
+
+    context 'with metrics_setting' do
+      before do
+        create(:project_metrics_setting, project: project, external_dashboard_url: 'http://gitlab.com')
+      end
+
+      it 'adds external_dashboard_url' do
+        expect(metrics_data['external-dashboard-url']).to eq('http://gitlab.com')
+      end
+    end
+  end
+end

spec/helpers/projects_helper_spec.rb

@@ -819,4 +819,26 @@ describe ProjectsHelper do
       expect(helper.can_import_members?).to eq true
     end
   end
+
+  describe '#metrics_external_dashboard_url' do
+    let(:project) { create(:project) }
+
+    before do
+      helper.instance_variable_set(:@project, project)
+    end
+
+    context 'metrics_setting exists' do
+      it 'returns external_dashboard_url' do
+        metrics_setting = create(:project_metrics_setting, project: project)
+
+        expect(helper.metrics_external_dashboard_url).to eq(metrics_setting.external_dashboard_url)
+      end
+    end
+
+    context 'metrics_setting does not exist' do
+      it 'returns nil' do
+        expect(helper.metrics_external_dashboard_url).to eq(nil)
+      end
+    end
+  end
 end