1 files changed, 72 insertions, 0 deletions
diff --git a/lib/gitlab/metrics/dashboard/importers/prometheus_metrics.rb b/lib/gitlab/metrics/dashboard/importers/prometheus_metrics.rb
new file mode 100644
index 00000000000..d1490d5d9b6
--- /dev/null
+++ b/lib/gitlab/metrics/dashboard/importers/prometheus_metrics.rb
@@ -0,0 +1,72 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Metrics
+    module Dashboard
+      module Importers
+        class PrometheusMetrics
+          ALLOWED_ATTRIBUTES = %i(title query y_label unit legend group dashboard_path).freeze
+
+          # Takes a JSON schema validated dashboard hash and
+          # imports metrics to database
+          def initialize(dashboard_hash, project:, dashboard_path:)
+            @dashboard_hash = dashboard_hash
+            @project = project
+            @dashboard_path = dashboard_path
+          end
+
+          def execute
+            import
+          rescue ActiveRecord::RecordInvalid, ::Gitlab::Metrics::Dashboard::Transformers::TransformerError
+            false
+          end
+
+          def execute!
+            import
+          end
+
+          private
+
+          attr_reader :dashboard_hash, :project, :dashboard_path
+
+          def import
+            delete_stale_metrics
+            create_or_update_metrics
+          end
+
+          # rubocop: disable CodeReuse/ActiveRecord
+          def create_or_update_metrics
+            # TODO: use upsert and worker for callbacks?
+            prometheus_metrics_attributes.each do |attributes|
+              prometheus_metric = PrometheusMetric.find_or_initialize_by(attributes.slice(:identifier, :project))
+              prometheus_metric.update!(attributes.slice(*ALLOWED_ATTRIBUTES))
+            end
+          end
+          # rubocop: enable CodeReuse/ActiveRecord
+
+          def delete_stale_metrics
+            identifiers = prometheus_metrics_attributes.map { |metric_attributes| metric_attributes[:identifier] }
+
+            stale_metrics = PrometheusMetric.for_project(project)
+              .for_dashboard_path(dashboard_path)
+              .for_group(Enums::PrometheusMetric.groups[:custom])
+              .not_identifier(identifiers)
+
+            # TODO: use destroy_all and worker for callbacks?
+            stale_metrics.each(&:destroy)
+          end
+
+          def prometheus_metrics_attributes
+            @prometheus_metrics_attributes ||= begin
+              Dashboard::Transformers::Yml::V1::PrometheusMetrics.new(
+                dashboard_hash,
+                project: project,
+                dashboard_path: dashboard_path
+              ).execute
+            end
+          end
+        end
+      end
+    end
+  end
+end