1 files changed, 80 insertions, 0 deletions
diff --git a/lib/gitlab/prometheus/queries/matched_metric_query.rb b/lib/gitlab/prometheus/queries/matched_metric_query.rb
new file mode 100644
index 00000000000..d920e9a749f
--- /dev/null
+++ b/lib/gitlab/prometheus/queries/matched_metric_query.rb
@@ -0,0 +1,80 @@
+module Gitlab
+  module Prometheus
+    module Queries
+      class MatchedMetricQuery < BaseQuery
+        MAX_QUERY_ITEMS = 40.freeze
+
+        def query
+          groups_data.map do |group, data|
+            {
+              group: group.name,
+              priority: group.priority,
+              active_metrics: data[:active_metrics],
+              metrics_missing_requirements: data[:metrics_missing_requirements]
+            }
+          end
+        end
+
+        private
+
+        def groups_data
+          metrics_groups = groups_with_active_metrics(Gitlab::Prometheus::MetricGroup.common_metrics)
+          lookup = active_series_lookup(metrics_groups)
+
+          groups = {}
+
+          metrics_groups.each do |group|
+            groups[group] ||= { active_metrics: 0, metrics_missing_requirements: 0 }
+            active_metrics = group.metrics.count { |metric| metric.required_metrics.all?(&lookup.method(:has_key?)) }
+
+            groups[group][:active_metrics] += active_metrics
+            groups[group][:metrics_missing_requirements] += group.metrics.count - active_metrics
+          end
+
+          groups
+        end
+
+        def active_series_lookup(metric_groups)
+          timeframe_start = 8.hours.ago
+          timeframe_end = Time.now
+
+          series = metric_groups.flat_map(&:metrics).flat_map(&:required_metrics).uniq
+
+          lookup = series.each_slice(MAX_QUERY_ITEMS).flat_map do |batched_series|
+            client_series(*batched_series, start: timeframe_start, stop: timeframe_end)
+              .select(&method(:has_matching_label?))
+              .map { |series_info| [series_info['__name__'], true] }
+          end
+          lookup.to_h
+        end
+
+        def has_matching_label?(series_info)
+          series_info.key?('environment')
+        end
+
+        def available_metrics
+          @available_metrics ||= client_label_values || []
+        end
+
+        def filter_active_metrics(metric_group)
+          metric_group.metrics.select! do |metric|
+            metric.required_metrics.all?(&available_metrics.method(:include?))
+          end
+          metric_group
+        end
+
+        def groups_with_active_metrics(metric_groups)
+          metric_groups.map(&method(:filter_active_metrics)).select { |group| group.metrics.any? }
+        end
+
+        def metrics_with_required_series(metric_groups)
+          metric_groups.flat_map do |group|
+            group.metrics.select do |metric|
+              metric.required_metrics.all?(&available_metrics.method(:include?))
+            end
+          end
+        end
+      end
+    end
+  end
+end