1 files changed, 99 insertions, 0 deletions
diff --git a/lib/gitlab/metrics/subscribers/external_http.rb b/lib/gitlab/metrics/subscribers/external_http.rb
new file mode 100644
index 00000000000..94c5d965200
--- /dev/null
+++ b/lib/gitlab/metrics/subscribers/external_http.rb
@@ -0,0 +1,99 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Metrics
+    module Subscribers
+      # Class for tracking the total time spent in external HTTP
+      # See more at https://gitlab.com/gitlab-org/labkit-ruby/-/blob/v0.14.0/lib/gitlab-labkit.rb#L18
+      class ExternalHttp < ActiveSupport::Subscriber
+        attach_to :external_http
+
+        DEFAULT_STATUS_CODE = 'undefined'
+
+        DETAIL_STORE = :external_http_detail_store
+        COUNTER = :external_http_count
+        DURATION = :external_http_duration_s
+
+        KNOWN_PAYLOAD_KEYS = [COUNTER, DURATION].freeze
+
+        def self.detail_store
+          ::Gitlab::SafeRequestStore[DETAIL_STORE] ||= []
+        end
+
+        def self.duration
+          Gitlab::SafeRequestStore[DURATION].to_f
+        end
+
+        def self.request_count
+          Gitlab::SafeRequestStore[COUNTER].to_i
+        end
+
+        def self.payload
+          {
+            COUNTER => request_count,
+            DURATION => duration
+          }
+        end
+
+        def request(event)
+          payload = event.payload
+          add_to_detail_store(payload)
+          add_to_request_store(payload)
+          expose_metrics(payload)
+        end
+
+        private
+
+        def current_transaction
+          ::Gitlab::Metrics::Transaction.current
+        end
+
+        def add_to_detail_store(payload)
+          return unless Gitlab::PerformanceBar.enabled_for_request?
+
+          self.class.detail_store << {
+            duration: payload[:duration],
+            scheme: payload[:scheme],
+            method: payload[:method],
+            host: payload[:host],
+            port: payload[:port],
+            path: payload[:path],
+            query: payload[:query],
+            code: payload[:code],
+            exception_object: payload[:exception_object],
+            backtrace: Gitlab::BacktraceCleaner.clean_backtrace(caller)
+          }
+        end
+
+        def add_to_request_store(payload)
+          return unless Gitlab::SafeRequestStore.active?
+
+          Gitlab::SafeRequestStore[COUNTER] = Gitlab::SafeRequestStore[COUNTER].to_i + 1
+          Gitlab::SafeRequestStore[DURATION] = Gitlab::SafeRequestStore[DURATION].to_f + payload[:duration].to_f
+        end
+
+        def expose_metrics(payload)
+          return unless current_transaction
+
+          labels = { method: payload[:method], code: payload[:code] || DEFAULT_STATUS_CODE }
+
+          current_transaction.increment(:gitlab_external_http_total, 1, labels) do
+            docstring 'External HTTP calls'
+            label_keys labels.keys
+          end
+
+          current_transaction.observe(:gitlab_external_http_duration_seconds, payload[:duration]) do
+            docstring 'External HTTP time'
+            buckets [0.001, 0.01, 0.1, 1.0, 2.0, 5.0]
+          end
+
+          if payload[:exception_object].present?
+            current_transaction.increment(:gitlab_external_http_exception_total, 1) do
+              docstring 'External HTTP exceptions'
+            end
+          end
+        end
+      end
+    end
+  end
+end