Split metrics from health controller into metrics controller

1 files changed, 41 insertions, 0 deletions

diff --git a/app/controllers/metrics_controller.rb b/app/controllers/metrics_controller.rb
new file mode 100644
index 00000000000..a4ba77e235f
--- /dev/null
+++ b/app/controllers/metrics_controller.rb
@@ -0,0 +1,41 @@
+require 'prometheus/client/formats/text'
+
+class MetricsController < ActionController::Base
+  protect_from_forgery with: :exception
+
+  CHECKS = [
+    Gitlab::HealthChecks::DbCheck,
+    Gitlab::HealthChecks::RedisCheck,
+    Gitlab::HealthChecks::FsShardsCheck,
+  ].freeze
+
+  def metrics
+    render_404 unless Gitlab::Metrics.prometheus_metrics_enabled?
+
+    metrics_text = Prometheus::Client::Formats::Text.marshal_multiprocess(Settings.gitlab['prometheus_multiproc_dir'])
+    response = health_metrics_text + "\n" + metrics_text
+
+    render text: response, content_type: 'text/plain; version=0.0.4'
+  end
+
+  private
+
+  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
+
+  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