Add sidekiq metrics endpoint and add http server to sidekiq

3 files changed, 123 insertions, 53 deletions

diff --git a/lib/gitlab/daemon.rb b/lib/gitlab/daemon.rb
new file mode 100644
index 00000000000..dfd17e35707
--- /dev/null
+++ b/lib/gitlab/daemon.rb
@@ -0,0 +1,62 @@
+module Gitlab
+  class Daemon
+    def self.initialize_instance(*args)
+      raise "#{name} singleton instance already initialized" if @instance
+      @instance = new(*args)
+      Kernel.at_exit(&@instance.method(:stop))
+      @instance
+    end
+
+    def self.instance
+      @instance ||= initialize_instance
+    end
+
+    attr_reader :thread
+
+    def thread?
+      !thread.nil?
+    end
+
+    def initialize
+      @mutex = Mutex.new
+    end
+
+    def enabled?
+      true
+    end
+
+    def start
+      return unless enabled?
+
+      @mutex.synchronize do
+        return thread if thread?
+
+        @thread = Thread.new { start_working }
+      end
+    end
+
+    def stop
+      @mutex.synchronize do
+        return unless thread?
+
+        stop_working
+
+        if thread
+          thread.wakeup if thread.alive?
+          thread.join
+          @thread = nil
+        end
+      end
+    end
+
+    private
+
+    def start_working
+      raise NotImplementedError
+    end
+
+    def stop_working
+      # no-ops
+    end
+  end
+end
diff --git a/lib/gitlab/metrics/base_sampler.rb b/lib/gitlab/metrics/base_sampler.rb
index 219accfc029..716d20bb91a 100644
--- a/lib/gitlab/metrics/base_sampler.rb
+++ b/lib/gitlab/metrics/base_sampler.rb
@@ -1,20 +1,7 @@
 require 'logger'
 module Gitlab
   module Metrics
-    class BaseSampler
-      def self.initialize_instance(*args)
-        raise "#{name} singleton instance already initialized" if @instance
-        @instance = new(*args)
-        at_exit(&@instance.method(:stop))
-        @instance
-      end
-
-      def self.instance
-        @instance
-      end
-
-      attr_reader :running
-
+    class BaseSampler < Daemon
       # interval - The sampling interval in seconds.
       def initialize(interval)
         interval_half = interval.to_f / 2
@@ -22,44 +9,7 @@ module Gitlab
         @interval = interval
         @interval_steps = (-interval_half..interval_half).step(0.1).to_a
 
-        @mutex = Mutex.new
-      end
-
-      def enabled?
-        true
-      end
-
-      def start
-        return unless enabled?
-
-        @mutex.synchronize do
-          return if running
-          @running = true
-
-          @thread = Thread.new do
-            sleep(sleep_interval)
-
-            while running
-              safe_sample
-
-              sleep(sleep_interval)
-            end
-          end
-        end
-      end
-
-      def stop
-        @mutex.synchronize do
-          return unless running
-
-          @running = false
-
-          if @thread
-            @thread.wakeup if @thread.alive?
-            @thread.join
-            @thread = nil
-          end
-        end
+        super()
       end
 
       def safe_sample
@@ -81,7 +31,7 @@ module Gitlab
       #    potentially missing anything that happens in between samples).
       # 2. Don't sample data at the same interval two times in a row.
       def sleep_interval
-        while step = @interval_steps.sample
+        while (step = @interval_steps.sample)
           if step != @last_step
             @last_step = step
 
@@ -89,6 +39,25 @@ module Gitlab
           end
         end
       end
+
+      private
+
+      attr_reader :running
+
+      def start_working
+        @running = true
+        sleep(sleep_interval)
+
+        while running
+          safe_sample
+
+          sleep(sleep_interval)
+        end
+      end
+
+      def stop_working
+        @running = false
+      end
     end
   end
 end
diff --git a/lib/gitlab/metrics/sidekiq_metrics_exporter.rb b/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
new file mode 100644
index 00000000000..5980a4ded2b
--- /dev/null
+++ b/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
@@ -0,0 +1,39 @@
+require 'webrick'
+require 'prometheus/client/rack/exporter'
+
+module Gitlab
+  module Metrics
+    class SidekiqMetricsExporter < Daemon
+      def enabled?
+        Gitlab::Metrics.metrics_folder_present? && settings.enabled
+      end
+
+      def settings
+        Settings.monitoring.sidekiq_exporter
+      end
+
+      private
+
+      attr_reader :server
+
+      def start_working
+        @server = ::WEBrick::HTTPServer.new(Port: settings.port, BindAddress: settings.address)
+        server.mount "/", Rack::Handler::WEBrick, rack_app
+        server.start
+      end
+
+      def stop_working
+        server.shutdown
+        @server = nil
+      end
+
+      def rack_app
+        Rack::Builder.app do
+          use Rack::Deflater
+          use ::Prometheus::Client::Rack::Exporter
+          run -> (env) { [404, {}, ['']] }
+        end
+      end
+    end
+  end
+end