1 files changed, 42 insertions, 0 deletions
diff --git a/lib/gitlab/event_store.rb b/lib/gitlab/event_store.rb
new file mode 100644
index 00000000000..3d7b6b27eb0
--- /dev/null
+++ b/lib/gitlab/event_store.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+# Gitlab::EventStore is a simple pub-sub mechanism that lets you publish
+# domain events and use Sidekiq workers as event handlers.
+#
+# It can be used to decouple domains from different bounded contexts
+# by publishing domain events and let any interested parties subscribe
+# to them.
+#
+module Gitlab
+  module EventStore
+    Error = Class.new(StandardError)
+    InvalidEvent = Class.new(Error)
+    InvalidSubscriber = Class.new(Error)
+
+    def self.publish(event)
+      instance.publish(event)
+    end
+
+    def self.instance
+      @instance ||= configure!
+    end
+
+    # Define all event subscriptions using:
+    #
+    #   store.subscribe(DomainA::SomeWorker, to: DomainB::SomeEvent)
+    #
+    # It is possible to subscribe to a subset of events matching a condition:
+    #
+    #   store.subscribe(DomainA::SomeWorker, to: DomainB::SomeEvent), if: ->(event) { event.data == :some_value }
+    #
+    def self.configure!
+      Store.new do |store|
+        ###
+        # Add subscriptions here:
+
+        store.subscribe ::MergeRequests::UpdateHeadPipelineWorker, to: ::Ci::PipelineCreatedEvent
+      end
+    end
+    private_class_method :configure!
+  end
+end