Move most of MetricsController logic to MetricsService

1 files changed, 38 insertions, 0 deletions

diff --git a/app/services/metrics_service.rb b/app/services/metrics_service.rb
new file mode 100644
index 00000000000..350c3639e92
--- /dev/null
+++ b/app/services/metrics_service.rb
@@ -0,0 +1,38 @@
+require 'prometheus/client/formats/text'
+
+class MetricsService
+  CHECKS = [
+    Gitlab::HealthChecks::DbCheck,
+    Gitlab::HealthChecks::RedisCheck,
+    Gitlab::HealthChecks::FsShardsCheck
+  ].freeze
+
+  def prometheus_metrics_text
+    Prometheus::Client::Formats::Text.marshal_multiprocess(multiprocess_metrics_path)
+  end
+
+  def health_metrics_text
+    results = CHECKS.flat_map(&:metrics)
+
+    types = results.map(&:name).uniq.map { |metric_name| "# TYPE #{metric_name} gauge" }
+    metrics = results.map(&method(:metric_to_prom_line))
+
+    types.concat(metrics).join("\n")
+  end
+
+  private
+
+  def multiprocess_metrics_path
+    Rails.root.join(ENV['prometheus_multiproc_dir'])
+  end
+
+  def metric_to_prom_line(metric)
+    labels = metric.labels&.map { |key, value| "#{key}=\"#{value}\"" }&.join(',') || ''
+
+    if labels.empty?
+      "#{metric.name} #{metric.value}"
+    else
+      "#{metric.name}{#{labels}} #{metric.value}"
+    end
+  end
+end