Move process specific metrics to ruby sampler

These metrics are not unicorn specific and can be used across ruby
processes

lib/gitlab/metrics/samplers/ruby_sampler.rb

@@ -23,25 +23,31 @@ module Gitlab
         end
 
         def init_metrics
-          metrics = {}
-          metrics[:sampler_duration] = ::Gitlab::Metrics.counter(with_prefix(:sampler, :duration_seconds_total), 'Sampler time', labels)
-          metrics[:total_time] = ::Gitlab::Metrics.counter(with_prefix(:gc, :duration_seconds_total), 'Total GC time', labels)
+          metrics = {
+            file_descriptors:           ::Gitlab::Metrics.gauge(with_prefix(:file, :descriptors), 'File descriptors used', labels, :livesum),
+            memory_usage:               ::Gitlab::Metrics.gauge(with_prefix(:memory, :bytes), 'Memory used', labels, :livesum),
+            process_cpu_seconds_total:  ::Gitlab::Metrics.gauge(:process_cpu_seconds_total, 'Process CPU seconds total'),
+            process_max_fds:            ::Gitlab::Metrics.gauge(:process_max_fds, 'Process max fds'),
+            process_start_time_seconds: ::Gitlab::Metrics.gauge(:process_start_time_seconds, 'Process start time seconds'),
+            sampler_duration:           ::Gitlab::Metrics.counter(with_prefix(:sampler, :duration_seconds_total), 'Sampler time', labels),
+            total_time:                 ::Gitlab::Metrics.counter(with_prefix(:gc, :duration_seconds_total), 'Total GC time', labels)
+          }
+
           GC.stat.keys.each do |key|
             metrics[key] = ::Gitlab::Metrics.gauge(with_prefix(:gc_stat, key), to_doc_string(key), labels, :livesum)
           end
 
-          metrics[:memory_usage] = ::Gitlab::Metrics.gauge(with_prefix(:memory, :bytes), 'Memory used', labels, :livesum)
-          metrics[:file_descriptors] = ::Gitlab::Metrics.gauge(with_prefix(:file, :descriptors), 'File descriptors used', labels, :livesum)
-
           metrics
         end
 
         def sample
           start_time = System.monotonic_time
 
-          metrics[:memory_usage].set(labels.merge(worker_label), System.memory_usage)
           metrics[:file_descriptors].set(labels.merge(worker_label), System.file_descriptor_count)
-
+          metrics[:memory_usage].set(labels.merge(worker_label), System.memory_usage)
+          metrics[:process_cpu_seconds_total].set(labels.merge(worker_label), ::Gitlab::Metrics::System.cpu_time)
+          metrics[:process_start_time_seconds].set(labels.merge(worker_label), ::Gitlab::Metrics::System.process_start_time)
+          metrics[:process_max_fds].set(labels.merge(worker_label), ::Gitlab::Metrics::System.max_open_file_descriptors)
           sample_gc
 
           metrics[:sampler_duration].increment(labels, System.monotonic_time - start_time)

lib/gitlab/metrics/samplers/unicorn_sampler.rb

@@ -16,10 +16,7 @@ module Gitlab
           {
             unicorn_active_connections: ::Gitlab::Metrics.gauge(:unicorn_active_connections, 'Unicorn active connections', {}, :max),
             unicorn_queued_connections: ::Gitlab::Metrics.gauge(:unicorn_queued_connections, 'Unicorn queued connections', {}, :max),
-            unicorn_workers:            ::Gitlab::Metrics.gauge(:unicorn_workers, 'Unicorn workers'),
-            process_cpu_seconds_total:  ::Gitlab::Metrics.gauge(:process_cpu_seconds_total, 'Process CPU seconds total'),
-            process_max_fds:            ::Gitlab::Metrics.gauge(:process_max_fds, 'Process max fds'),
-            process_start_time_seconds: ::Gitlab::Metrics.gauge(:process_start_time_seconds, 'Process start time seconds')
+            unicorn_workers:            ::Gitlab::Metrics.gauge(:unicorn_workers, 'Unicorn workers')
           }
         end
 
@@ -39,9 +36,6 @@ module Gitlab
             metrics[:unicorn_queued_connections].set({ socket_type: 'unix', socket_address: addr }, stats.queued)
           end
 
-          metrics[:process_cpu_seconds_total].set({ pid: nil }, ::Gitlab::Metrics::System.cpu_time)
-          metrics[:process_start_time_seconds].set({ pid: nil }, ::Gitlab::Metrics::System.process_start_time)
-          metrics[:process_max_fds].set({ pid: nil }, ::Gitlab::Metrics::System.max_open_file_descriptors)
           metrics[:unicorn_workers].set({}, unicorn_workers_count)
         end
 

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

@@ -10,8 +10,11 @@ describe Gitlab::Metrics::Samplers::RubySampler do
 
   describe '#sample' do
     it 'samples various statistics' do
-      expect(Gitlab::Metrics::System).to receive(:memory_usage)
+      expect(Gitlab::Metrics::System).to receive(:cpu_time)
       expect(Gitlab::Metrics::System).to receive(:file_descriptor_count)
+      expect(Gitlab::Metrics::System).to receive(:memory_usage)
+      expect(Gitlab::Metrics::System).to receive(:process_start_time)
+      expect(Gitlab::Metrics::System).to receive(:max_open_file_descriptors)
       expect(sampler).to receive(:sample_gc)
 
       sampler.sample
@@ -34,6 +37,27 @@ describe Gitlab::Metrics::Samplers::RubySampler do
       sampler.sample
     end
 
+    it 'adds a metric containing the processes total cpu time' do
+      expect(Gitlab::Metrics::System).to receive(:cpu_time).and_return(0.51)
+      expect(sampler.metrics[:process_cpu_seconds_total]).to receive(:set).with({}, 0.51)
+
+      sampler.sample
+    end
+
+    it 'adds a metric containing the process start time' do
+      expect(Gitlab::Metrics::System).to receive(:process_start_time).and_return(12345)
+      expect(sampler.metrics[:process_start_time_seconds]).to receive(:set).with({}, 12345)
+
+      sampler.sample
+    end
+
+    it 'adds a metric containing the process max file descriptors' do
+      expect(Gitlab::Metrics::System).to receive(:max_open_file_descriptors).and_return(1024)
+      expect(sampler.metrics[:process_max_fds]).to receive(:set).with({}, 1024)
+
+      sampler.sample
+    end
+
     it 'clears any GC profiles' do
       expect(GC::Profiler).to receive(:clear)
 

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

@@ -80,22 +80,15 @@ describe Gitlab::Metrics::Samplers::UnicornSampler do
 
     context 'additional metrics' do
       let(:cpu_time) { 3.14 }
-      let(:process_start_time) { 19100.24 }
-      let(:process_max_fds) { 1024 }
       let(:unicorn_workers) { 2 }
 
       before do
         allow(unicorn).to receive(:listener_names).and_return([""])
         allow(::Gitlab::Metrics::System).to receive(:cpu_time).and_return(cpu_time)
-        allow(::Gitlab::Metrics::System).to receive(:process_start_time).and_return(process_start_time)
-        allow(::Gitlab::Metrics::System).to receive(:max_open_file_descriptors).and_return(process_max_fds)
         allow(subject).to receive(:unicorn_workers_count).and_return(unicorn_workers)
       end
 
       it "sets additional metrics" do
-        expect(subject.metrics[:process_cpu_seconds_total]).to receive(:set).with({ pid: nil }, cpu_time)
-        expect(subject.metrics[:process_start_time_seconds]).to receive(:set).with({ pid: nil }, process_start_time)
-        expect(subject.metrics[:process_max_fds]).to receive(:set).with({ pid: nil }, process_max_fds)
         expect(subject.metrics[:unicorn_workers]).to receive(:set).with({}, unicorn_workers)
 
         subject.sample