1 files changed, 41 insertions, 0 deletions
diff --git a/lib/gitlab/health_checks/unicorn_check.rb b/lib/gitlab/health_checks/unicorn_check.rb
new file mode 100644
index 00000000000..a30ae015257
--- /dev/null
+++ b/lib/gitlab/health_checks/unicorn_check.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module HealthChecks
+    # This check can only be run on Unicorn `master` process
+    class UnicornCheck
+      extend SimpleAbstractCheck
+
+      class << self
+        include Gitlab::Utils::StrongMemoize
+
+        private
+
+        def metric_prefix
+          'unicorn_check'
+        end
+
+        def successful?(result)
+          result > 0
+        end
+
+        def check
+          return unless http_servers
+
+          http_servers.sum(&:worker_processes) # rubocop: disable CodeReuse/ActiveRecord
+        end
+
+        # Traversal of ObjectSpace is expensive, on fully loaded application
+        # it takes around 80ms. The instances of HttpServers are not a subject
+        # to change so we can cache the list of servers.
+        def http_servers
+          strong_memoize(:http_servers) do
+            next unless defined?(::Unicorn::HttpServer)
+
+            ObjectSpace.each_object(::Unicorn::HttpServer).to_a
+          end
+        end
+      end
+    end
+  end
+end