Merge branch '61964-unicorn-instrumentation' into 'master'

Adds ruby and unicorn instrumentation

Closes #61964

See merge request gitlab-org/gitlab-ce!28499

7 files changed, 156 insertions, 35 deletions

diff --git a/doc/administration/monitoring/prometheus/gitlab_metrics.md b/doc/administration/monitoring/prometheus/gitlab_metrics.md
index 4529bd3bee3..3dcd1593099 100644
--- a/doc/administration/monitoring/prometheus/gitlab_metrics.md
+++ b/doc/administration/monitoring/prometheus/gitlab_metrics.md
@@ -43,10 +43,11 @@ The following metrics are available:
 | redis_ping_latency_seconds        | Gauge     | 9.4   | Round trip time of the redis ping |
 | user_session_logins_total         | Counter   | 9.4   | Counter of how many users have logged in |
 | upload_file_does_not_exist        | Counter   | 10.7 in EE, 11.5 in CE  | Number of times an upload record could not find its file |
-| failed_login_captcha_total        | Gauge | 11.0 | Counter of failed CAPTCHA attempts during login |
-| successful_login_captcha_total    | Gauge | 11.0 | Counter of successful CAPTCHA attempts during login |
-| unicorn_active_connections        | Gauge | 11.0 | The number of active Unicorn connections (workers) |
-| unicorn_queued_connections        | Gauge | 11.0 | The number of queued Unicorn connections |
+| failed_login_captcha_total        | Gauge     | 11.0  | Counter of failed CAPTCHA attempts during login |
+| successful_login_captcha_total    | Gauge     | 11.0  | Counter of successful CAPTCHA attempts during login |
+| unicorn_active_connections        | Gauge     | 11.0  | The number of active Unicorn connections (workers) |
+| unicorn_queued_connections        | Gauge     | 11.0  | The number of queued Unicorn connections |
+| unicorn_workers                   | Gauge     | 12.0  | The number of Unicorn workers |
 
 ## Sidekiq Metrics available for Geo **[PREMIUM]**
 
@@ -86,8 +87,8 @@ the `monitoring.sidekiq_exporter` configuration option in `gitlab.yml`.
 | geo_wikis_checksum_mismatch_count            | Gauge   | 10.7  | Number of wikis that checksum mismatch on secondary | url
 | geo_repositories_checked_count               | Gauge   | 11.1  | Number of repositories that have been checked via `git fsck` | url
 | geo_repositories_checked_failed_count        | Gauge   | 11.1  | Number of repositories that have a failure from `git fsck` | url
-| geo_repositories_retrying_verification_count  | Gauge   | 11.2  | Number of repositories verification failures that Geo is actively trying to correct on secondary  | url
-| geo_wikis_retrying_verification_count         | Gauge   | 11.2  | Number of wikis verification failures that Geo is actively trying to correct on secondary | url
+| geo_repositories_retrying_verification_count | Gauge   | 11.2  | Number of repositories verification failures that Geo is actively trying to correct on secondary  | url
+| geo_wikis_retrying_verification_count        | Gauge   | 11.2  | Number of wikis verification failures that Geo is actively trying to correct on secondary | url
 
 ### Ruby metrics
 
@@ -100,6 +101,10 @@ Some basic Ruby runtime metrics are available:
 | ruby_file_descriptors                  | Gauge     | 11.1  | File descriptors per process |
 | ruby_memory_bytes                      | Gauge     | 11.1  | Memory usage by process |
 | ruby_sampler_duration_seconds_total    | Counter   | 11.1  | Time spent collecting stats |
+| ruby_process_cpu_seconds_total         | Gauge     | 12.0  | Total amount of CPU time per process |
+| ruby_process_max_fds                   | Gauge     | 12.0  | Maximum number of open file descriptors per process |
+| ruby_process_resident_memory_bytes     | Gauge     | 12.0  | Memory usage by process, measured in bytes |
+| ruby_process_start_time_seconds        | Gauge     | 12.0  | The elapsed time between system boot and the process started, measured in seconds |
 
 [GC.stat]: https://ruby-doc.org/core-2.3.0/GC.html#method-c-stat
 
diff --git a/lib/gitlab/metrics/samplers/ruby_sampler.rb b/lib/gitlab/metrics/samplers/ruby_sampler.rb
index 18a69321905..4d9c43f37e7 100644
--- a/lib/gitlab/metrics/samplers/ruby_sampler.rb
+++ b/lib/gitlab/metrics/samplers/ruby_sampler.rb
@@ -23,25 +23,32 @@ 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_bytes:                   ::Gitlab::Metrics.gauge(with_prefix(:memory, :bytes), 'Memory used', labels, :livesum),
+            process_cpu_seconds_total:      ::Gitlab::Metrics.gauge(with_prefix(:process, :cpu_seconds_total), 'Process CPU seconds total'),
+            process_max_fds:                ::Gitlab::Metrics.gauge(with_prefix(:process, :max_fds), 'Process max fds'),
+            process_resident_memory_bytes:  ::Gitlab::Metrics.gauge(with_prefix(:process, :resident_memory_bytes), 'Memory used', labels, :livesum),
+            process_start_time_seconds:     ::Gitlab::Metrics.gauge(with_prefix(: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[:process_cpu_seconds_total].set(labels.merge(worker_label), ::Gitlab::Metrics::System.cpu_time)
+          metrics[:process_max_fds].set(labels.merge(worker_label), ::Gitlab::Metrics::System.max_open_file_descriptors)
+          metrics[:process_start_time_seconds].set(labels.merge(worker_label), ::Gitlab::Metrics::System.process_start_time)
+          set_memory_usage_metrics
           sample_gc
 
           metrics[:sampler_duration].increment(labels, System.monotonic_time - start_time)
@@ -61,6 +68,14 @@ module Gitlab
           metrics[:total_time].increment(labels, GC::Profiler.total_time)
         end
 
+        def set_memory_usage_metrics
+          memory_usage = System.memory_usage
+          memory_labels = labels.merge(worker_label)
+
+          metrics[:memory_bytes].set(memory_labels, memory_usage)
+          metrics[:process_resident_memory_bytes].set(memory_labels, memory_usage)
+        end
+
         def worker_label
           return {} unless defined?(Unicorn::Worker)
 
diff --git a/lib/gitlab/metrics/samplers/unicorn_sampler.rb b/lib/gitlab/metrics/samplers/unicorn_sampler.rb
index bec64e864b3..9af7e0afed4 100644
--- a/lib/gitlab/metrics/samplers/unicorn_sampler.rb
+++ b/lib/gitlab/metrics/samplers/unicorn_sampler.rb
@@ -4,16 +4,16 @@ module Gitlab
   module Metrics
     module Samplers
       class UnicornSampler < BaseSampler
-        def initialize(interval)
-          super(interval)
+        def metrics
+          @metrics ||= init_metrics
         end
 
-        def unicorn_active_connections
-          @unicorn_active_connections ||= ::Gitlab::Metrics.gauge(:unicorn_active_connections, 'Unicorn active connections', {}, :max)
-        end
-
-        def unicorn_queued_connections
-          @unicorn_queued_connections ||= ::Gitlab::Metrics.gauge(:unicorn_queued_connections, 'Unicorn queued connections', {}, :max)
+        def init_metrics
+          {
+            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')
+          }
         end
 
         def enabled?
@@ -23,14 +23,13 @@ module Gitlab
 
         def sample
           Raindrops::Linux.tcp_listener_stats(tcp_listeners).each do |addr, stats|
-            unicorn_active_connections.set({ socket_type: 'tcp', socket_address: addr }, stats.active)
-            unicorn_queued_connections.set({ socket_type: 'tcp', socket_address: addr }, stats.queued)
+            set_unicorn_connection_metrics('tcp', addr, stats)
           end
-
           Raindrops::Linux.unix_listener_stats(unix_listeners).each do |addr, stats|
-            unicorn_active_connections.set({ socket_type: 'unix', socket_address: addr }, stats.active)
-            unicorn_queued_connections.set({ socket_type: 'unix', socket_address: addr }, stats.queued)
+            set_unicorn_connection_metrics('unix', addr, stats)
           end
+
+          metrics[:unicorn_workers].set({}, unicorn_workers_count)
         end
 
         private
@@ -39,6 +38,13 @@ module Gitlab
           @tcp_listeners ||= Unicorn.listener_names.grep(%r{\A[^/]+:\d+\z})
         end
 
+        def set_unicorn_connection_metrics(type, addr, stats)
+          labels = { socket_type: type, socket_address: addr }
+
+          metrics[:unicorn_active_connections].set(labels, stats.active)
+          metrics[:unicorn_queued_connections].set(labels, stats.queued)
+        end
+
         def unix_listeners
           @unix_listeners ||= Unicorn.listener_names - tcp_listeners
         end
@@ -46,6 +52,10 @@ module Gitlab
         def unicorn_with_listeners?
           defined?(Unicorn) && Unicorn.listener_names.any?
         end
+
+        def unicorn_workers_count
+          `pgrep -f '[u]nicorn_rails worker.+ #{Rails.root.to_s}'`.split.count
+        end
       end
     end
   end
diff --git a/lib/gitlab/metrics/system.rb b/lib/gitlab/metrics/system.rb
index 426496855e3..33c0de91c11 100644
--- a/lib/gitlab/metrics/system.rb
+++ b/lib/gitlab/metrics/system.rb
@@ -23,6 +23,22 @@ module Gitlab
         def self.file_descriptor_count
           Dir.glob('/proc/self/fd/*').length
         end
+
+        def self.max_open_file_descriptors
+          match = File.read('/proc/self/limits').match(/Max open files\s*(\d+)/)
+
+          return unless match && match[1]
+
+          match[1].to_i
+        end
+
+        def self.process_start_time
+          fields = File.read('/proc/self/stat').split
+
+          # fields[21] is linux proc stat field "(22) starttime".
+          # The value is expressed in clock ticks, divide by clock ticks for seconds.
+          ( fields[21].to_i || 0 ) / clk_tck
+        end
       else
         def self.memory_usage
           0.0
@@ -31,6 +47,14 @@ module Gitlab
         def self.file_descriptor_count
           0
         end
+
+        def self.max_open_file_descriptors
+          0
+        end
+
+        def self.process_start_time
+          0
+        end
       end
 
       # THREAD_CPUTIME is not supported on OS X
@@ -59,6 +83,10 @@ module Gitlab
       def self.monotonic_time
         Process.clock_gettime(Process::CLOCK_MONOTONIC, :float_second)
       end
+
+      def self.clk_tck
+        @clk_tck ||= `getconf CLK_TCK`.to_i
+      end
     end
   end
 end
diff --git a/spec/lib/gitlab/metrics/samplers/ruby_sampler_spec.rb b/spec/lib/gitlab/metrics/samplers/ruby_sampler_spec.rb
index 7972ff253fe..aaf8c9fa2a0 100644
--- a/spec/lib/gitlab/metrics/samplers/ruby_sampler_spec.rb
+++ b/spec/lib/gitlab/metrics/samplers/ruby_sampler_spec.rb
@@ -10,17 +10,20 @@ 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
     end
 
-    it 'adds a metric containing the memory usage' do
+    it 'adds a metric containing the process resident memory bytes' do
       expect(Gitlab::Metrics::System).to receive(:memory_usage).and_return(9000)
 
-      expect(sampler.metrics[:memory_usage]).to receive(:set).with({}, 9000)
+      expect(sampler.metrics[:process_resident_memory_bytes]).to receive(:set).with({}, 9000)
 
       sampler.sample
     end
@@ -34,6 +37,27 @@ describe Gitlab::Metrics::Samplers::RubySampler do
       sampler.sample
     end
 
+    it 'adds a metric containing the process 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)
 
diff --git a/spec/lib/gitlab/metrics/samplers/unicorn_sampler_spec.rb b/spec/lib/gitlab/metrics/samplers/unicorn_sampler_spec.rb
index 4b03f3c2532..090e456644f 100644
--- a/spec/lib/gitlab/metrics/samplers/unicorn_sampler_spec.rb
+++ b/spec/lib/gitlab/metrics/samplers/unicorn_sampler_spec.rb
@@ -39,8 +39,8 @@ describe Gitlab::Metrics::Samplers::UnicornSampler do
         it 'updates metrics type unix and with addr' do
           labels = { socket_type: 'unix', socket_address: socket_address }
 
-          expect(subject).to receive_message_chain(:unicorn_active_connections, :set).with(labels, 'active')
-          expect(subject).to receive_message_chain(:unicorn_queued_connections, :set).with(labels, 'queued')
+          expect(subject.metrics[:unicorn_active_connections]).to receive(:set).with(labels, 'active')
+          expect(subject.metrics[:unicorn_queued_connections]).to receive(:set).with(labels, 'queued')
 
           subject.sample
         end
@@ -50,7 +50,6 @@ describe Gitlab::Metrics::Samplers::UnicornSampler do
     context 'unicorn listens on tcp sockets' do
       let(:tcp_socket_address) { '0.0.0.0:8080' }
       let(:tcp_sockets) { [tcp_socket_address] }
-
       before do
         allow(unicorn).to receive(:listener_names).and_return(tcp_sockets)
       end
@@ -71,13 +70,29 @@ describe Gitlab::Metrics::Samplers::UnicornSampler do
         it 'updates metrics type unix and with addr' do
           labels = { socket_type: 'tcp', socket_address: tcp_socket_address }
 
-          expect(subject).to receive_message_chain(:unicorn_active_connections, :set).with(labels, 'active')
-          expect(subject).to receive_message_chain(:unicorn_queued_connections, :set).with(labels, 'queued')
+          expect(subject.metrics[:unicorn_active_connections]).to receive(:set).with(labels, 'active')
+          expect(subject.metrics[:unicorn_queued_connections]).to receive(:set).with(labels, 'queued')
 
           subject.sample
         end
       end
     end
+
+    context 'additional metrics' do
+      let(:unicorn_workers) { 2 }
+
+      before do
+        allow(unicorn).to receive(:listener_names).and_return([""])
+        allow(::Gitlab::Metrics::System).to receive(:cpu_time).and_return(3.14)
+        allow(subject).to receive(:unicorn_workers_count).and_return(unicorn_workers)
+      end
+
+      it "sets additional metrics" do
+        expect(subject.metrics[:unicorn_workers]).to receive(:set).with({}, unicorn_workers)
+
+        subject.sample
+      end
+    end
   end
 
   describe '#start' do
diff --git a/spec/lib/gitlab/metrics/system_spec.rb b/spec/lib/gitlab/metrics/system_spec.rb
index 14afcdf5daa..b0603d96eb2 100644
--- a/spec/lib/gitlab/metrics/system_spec.rb
+++ b/spec/lib/gitlab/metrics/system_spec.rb
@@ -13,6 +13,18 @@ describe Gitlab::Metrics::System do
         expect(described_class.file_descriptor_count).to be > 0
       end
     end
+
+    describe '.max_open_file_descriptors' do
+      it 'returns the max allowed open file descriptors' do
+        expect(described_class.max_open_file_descriptors).to be > 0
+      end
+    end
+
+    describe '.process_start_time' do
+      it 'returns the process start time' do
+        expect(described_class.process_start_time).to be > 0
+      end
+    end
   else
     describe '.memory_usage' do
       it 'returns 0.0' do
@@ -25,6 +37,18 @@ describe Gitlab::Metrics::System do
         expect(described_class.file_descriptor_count).to eq(0)
       end
     end
+
+    describe '.max_open_file_descriptors' do
+      it 'returns 0' do
+        expect(described_class.max_open_file_descriptors).to eq(0)
+      end
+    end
+
+    describe 'process_start_time' do
+      it 'returns 0' do
+        expect(described_class.process_start_time).to eq(0)
+      end
+    end
   end
 
   describe '.cpu_time' do