1 files changed, 78 insertions, 0 deletions
diff --git a/app/services/metrics/dashboard/dynamic_embed_service.rb b/app/services/metrics/dashboard/dynamic_embed_service.rb
new file mode 100644
index 00000000000..db5b7c9e32a
--- /dev/null
+++ b/app/services/metrics/dashboard/dynamic_embed_service.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+# Responsible for returning a filtered project dashboard
+# containing only the request-provided metrics. The result
+# is then cached for future requests. Metrics are identified
+# based on a combination of identifiers for now, but the ideal
+# would be similar to the approach in DefaultEmbedService, but
+# a single unique identifier is not currently available across
+# all metric types (custom, project-defined, cluster, or system).
+#
+# Use Gitlab::Metrics::Dashboard::Finder to retrive dashboards.
+module Metrics
+  module Dashboard
+    class DynamicEmbedService < ::Metrics::Dashboard::BaseEmbedService
+      include Gitlab::Utils::StrongMemoize
+
+      class << self
+        # Determines whether the provided params are sufficient
+        # to uniquely identify a panel from a yml-defined dashboard.
+        #
+        # See https://docs.gitlab.com/ee/user/project/integrations/prometheus.html#defining-custom-dashboards-per-project
+        # for additional info on defining custom dashboards.
+        def valid_params?(params)
+          [
+            params[:embedded],
+            params[:group].present?,
+            params[:title].present?,
+            params[:y_label]
+          ].all?
+        end
+      end
+
+      # Returns a new dashboard with only the matching
+      # metrics from the system dashboard, stripped of groups.
+      # @return [Hash]
+      def get_raw_dashboard
+        not_found! if panels.empty?
+
+        { 'panel_groups' => [{ 'panels' => panels }] }
+      end
+
+      private
+
+      def panels
+        strong_memoize(:panels) do
+          not_found! unless base_dashboard
+          not_found! unless groups = base_dashboard['panel_groups']
+          not_found! unless matching_group = find_group(groups)
+          not_found! unless all_panels = matching_group['panels']
+
+          find_panels(all_panels)
+        end
+      end
+
+      def base_dashboard
+        strong_memoize(:base_dashboard) do
+          Gitlab::Metrics::Dashboard::Finder.find_raw(project, dashboard_path: dashboard_path)
+        end
+      end
+
+      def find_group(groups)
+        groups.find do |candidate_group|
+          candidate_group['group'] == group
+        end
+      end
+
+      def find_panels(all_panels)
+        all_panels.select do |panel|
+          panel['title'] == title && panel['y_label'] == y_label
+        end
+      end
+
+      def not_found!
+        panels_not_found!(identifiers)
+      end
+    end
+  end
+end