Merge branch 'puma-fix' into 'master'

Ignore Puma empty worker stats

See merge request gitlab-org/gitlab-ce!28932

lib/gitlab/metrics/samplers/puma_sampler.rb

@@ -51,10 +51,11 @@ module Gitlab
           set_master_metrics(stats)
 
           stats['worker_status'].each do |worker|
+            last_status = worker['last_status']
             labels = { worker: "worker_#{worker['index']}" }
 
             metrics[:puma_phase].set(labels, worker['phase'])
-            set_worker_metrics(worker['last_status'], labels)
+            set_worker_metrics(last_status, labels) if last_status.present?
           end
         end
 

spec/lib/gitlab/metrics/samplers/puma_sampler_spec.rb

@@ -61,6 +61,33 @@ describe Gitlab::Metrics::Samplers::PumaSampler do
       end
     end
 
+    context 'with empty worker stats' do
+      let(:puma_stats) do
+        <<~EOS
+        {
+          "workers": 2,
+          "phase": 2,
+          "booted_workers": 2,
+          "old_workers": 0,
+          "worker_status": [{
+            "pid": 32534,
+            "index": 0,
+            "phase": 1,
+            "booted": true,
+            "last_checkin": "2019-05-15T07:57:55Z",
+            "last_status": {}
+          }]
+        }
+        EOS
+      end
+
+      it 'does not log worker stats' do
+        expect(subject).not_to receive(:set_worker_metrics)
+
+        subject.sample
+      end
+    end
+
     context 'in single mode' do
       let(:puma_stats) do
         <<~EOS