Merge branch 'instrument-infra' into 'master'

Add Prometheus metrics endpoint and basic infrastructure to meter code

See merge request !11553

1 files changed, 33 insertions, 0 deletions

diff --git a/app/services/metrics_service.rb b/app/services/metrics_service.rb
new file mode 100644
index 00000000000..d726db4e99b
--- /dev/null
+++ b/app/services/metrics_service.rb
@@ -0,0 +1,33 @@
+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
+    metrics = CHECKS.flat_map(&:metrics)
+
+    formatter.marshal(metrics)
+  end
+
+  def metrics_text
+    "#{health_metrics_text}#{prometheus_metrics_text}"
+  end
+
+  private
+
+  def formatter
+    @formatter ||= Gitlab::HealthChecks::PrometheusTextFormat.new
+  end
+
+  def multiprocess_metrics_path
+    @multiprocess_metrics_path ||= Rails.root.join(ENV['prometheus_multiproc_dir']).freeze
+  end
+end