Merge branch '30357-http_request_duration_seconds' into 'master'

Initialize http_request_duration_seconds metric

Closes #30357

See merge request gitlab-org/gitlab!17377

config/initializers/7_prometheus_metrics.rb

@@ -54,5 +54,7 @@ if !Rails.env.test? && Gitlab::Metrics.prometheus_metrics_enabled?
     elsif defined?(::Puma)
       Gitlab::Metrics::Samplers::PumaSampler.instance(Settings.monitoring.puma_sampler_interval).start
     end
+
+    Gitlab::Metrics::RequestsRackMiddleware.initialize_http_request_duration_seconds
   end
 end

lib/gitlab/metrics/requests_rack_middleware.rb

@@ -3,6 +3,18 @@
 module Gitlab
   module Metrics
     class RequestsRackMiddleware
+      HTTP_METHODS = {
+        "delete" => %w(200 202 204 303 400 401 403 404 410 422 500 503),
+        "get" => %w(200 204 301 302 303 304 307 400 401 403 404 410 412 422 429 500 503),
+        "head" => %w(200 204 301 302 303 304 400 401 403 404 410 429 500 503),
+        "options" => %w(200 404),
+        "patch" => %w(200 202 204 400 403 404 409 416 422 500),
+        "post" => %w(200 201 202 204 301 302 303 304 400 401 403 404 406 409 410 412 413 415 422 429 500 503),
+        "propfind" => %w(404),
+        "put" => %w(200 202 204 400 401 403 404 405 406 409 410 415 422 500),
+        "report" =>  %w(404)
+      }.freeze
+
       def initialize(app)
         @app = app
       end
@@ -20,6 +32,14 @@ module Gitlab
                                                            {}, [0.05, 0.1, 0.25, 0.5, 0.7, 1, 2.5, 5, 10, 25])
       end
 
+      def self.initialize_http_request_duration_seconds
+        HTTP_METHODS.each do |method, statuses|
+          statuses.each do |status|
+            http_request_duration_seconds.get({ method: method, status: status })
+          end
+        end
+      end
+
       def call(env)
         method = env['REQUEST_METHOD'].downcase
         started = Time.now.to_f

spec/lib/gitlab/metrics/requests_rack_middleware_spec.rb

@@ -63,5 +63,19 @@ describe Gitlab::Metrics::RequestsRackMiddleware do
         expect { subject.call(env) }.to raise_error(StandardError)
       end
     end
+
+    describe '.initialize_http_request_duration_seconds' do
+      it "sets labels" do
+        expected_labels = []
+        described_class::HTTP_METHODS.each do |method, statuses|
+          statuses.each do |status|
+            expected_labels << { method: method, status: status }
+          end
+        end
+
+        described_class.initialize_http_request_duration_seconds
+        expect(described_class.http_request_duration_seconds.values.keys).to include(*expected_labels)
+      end
+    end
   end
 end