Add #find_for method to PrometheusDashboard

In order to be able to build new metrics dashboard object
from yml definitions we need to add new method to
PerformanceMonitoring::PrometheusDashboard

app/models/performance_monitoring/prometheus_dashboard.rb

@@ -4,27 +4,41 @@ module PerformanceMonitoring
   class PrometheusDashboard
     include ActiveModel::Model
 
-    attr_accessor :dashboard, :panel_groups
+    attr_accessor :dashboard, :panel_groups, :path, :environment, :priority
 
     validates :dashboard, presence: true
     validates :panel_groups, presence: true
 
-    def self.from_json(json_content)
-      dashboard = new(
-        dashboard: json_content['dashboard'],
-        panel_groups: json_content['panel_groups'].map { |group| PrometheusPanelGroup.from_json(group) }
-      )
-
-      dashboard.tap(&:validate!)
+    class << self
+      def from_json(json_content)
+        dashboard = new(
+          dashboard: json_content['dashboard'],
+          panel_groups: json_content['panel_groups'].map { |group| PrometheusPanelGroup.from_json(group) }
+        )
+
+        dashboard.tap(&:validate!)
+      end
+
+      def find_for(project:, user:, path:, options: {})
+        dashboard_response = Gitlab::Metrics::Dashboard::Finder.find(project, user, options.merge(dashboard_path: path))
+        return unless dashboard_response[:status] == :success
+
+        new(
+          {
+            path: path,
+            environment: options[:environment]
+          }.merge(dashboard_response[:dashboard])
+        )
+      end
     end
 
     def to_yaml
-      self.as_json(only: valid_attributes).to_yaml
+      self.as_json(only: yaml_valid_attributes).to_yaml
     end
 
     private
 
-    def valid_attributes
+    def yaml_valid_attributes
       %w(panel_groups panels metrics group priority type title y_label weight id unit label query query_range dashboard)
     end
   end

ee/spec/models/performance_monitoring/prometheus_dashboard_spec.rb

@@ -55,15 +55,43 @@ describe PerformanceMonitoring::PrometheusDashboard do
     end
   end
 
+  describe '.find_for' do
+    let(:project) { build_stubbed(:project) }
+    let(:user) { build_stubbed(:user) }
+    let(:environment) { build_stubbed(:environment) }
+    let(:path) { ::Metrics::Dashboard::SystemDashboardService::DASHBOARD_PATH }
+
+    context 'dashboard has been found' do
+      it 'uses dashboard finder to find and load dashboard data and returns dashboard instance', :aggregate_failures do
+        expect(Gitlab::Metrics::Dashboard::Finder).to receive(:find).with(project, user, environment: environment, dashboard_path: path).and_return(status: :success, dashboard: json_content)
+
+        dashboard_instance = described_class.find_for(project: project, user: user, path: path, options: { environment: environment })
+
+        expect(dashboard_instance).to be_instance_of described_class
+        expect(dashboard_instance.environment).to be environment
+        expect(dashboard_instance.path).to be path
+      end
+    end
+
+    context 'dashboard has NOT been found' do
+      it 'returns nil' do
+        allow(Gitlab::Metrics::Dashboard::Finder).to receive(:find).and_return(status: :error)
+
+        dashboard_instance = described_class.find_for(project: project, user: user, path: path, options: { environment: environment })
+
+        expect(dashboard_instance).to be_nil
+      end
+    end
+  end
+
   describe '#to_yaml' do
+    subject { prometheus_dashboard.to_yaml }
+
+    let(:prometheus_dashboard) { described_class.from_json(json_content) }
     let(:expected_yaml) do
       "---\npanel_groups:\n- panels:\n  - metrics:\n    - id: metric_of_ages\n      unit: count\n      label: Metric of Ages\n      query: \n      query_range: http_requests_total\n    type: area-chart\n    title: Chart Title\n    y_label: Y-Axis\n    weight: \n  group: Group Title\n  priority: \ndashboard: Dashboard Title\n"
     end
 
-    let(:prometheus_dashboard) { described_class.from_json(json_content) }
-
-    let(:subject) { prometheus_dashboard.to_yaml }
-
     it { is_expected.to eq(expected_yaml) }
   end
 end