Add an event store for hashed migration events

app/services/geo/hashed_storage_migrated_event_store.rb

+module Geo
+  class HashedStorageMigratedEventStore < EventStore
+    self.event_type = :hashed_storage_migrated_event
+
+    private
+
+    def build_event
+      Geo::HashedStorageMigratedEvent.new(
+        project: project,
+        old_storage_version: old_storage_version,
+        new_storage_version: project.storage_version,
+        repository_storage_name: project.repository.storage,
+        repository_storage_path: project.repository_storage_path,
+        old_disk_path: old_disk_path,
+        new_disk_path: project.disk_path,
+        old_wiki_disk_path: old_wiki_disk_path,
+        new_wiki_disk_path: project.wiki.disk_path
+      )
+    end
+
+    def old_storage_version
+      params.fetch(:old_storage_version)
+    end
+
+    def old_disk_path
+      params.fetch(:old_disk_path)
+    end
+
+    def old_wiki_disk_path
+      "#{old_disk_path}.wiki"
+    end
+  end
+end

spec/services/geo/hashed_storage_migrated_event_store_spec.rb

+require 'spec_helper'
+
+describe Geo::HashedStorageMigratedEventStore do
+  set(:project) { create(:project, :hashed, path: 'bar') }
+  set(:secondary_node) { create(:geo_node) }
+  let(:old_disk_path) { "#{project.namespace.full_path}/foo" }
+  let(:old_wiki_disk_path) { "#{old_disk_path}.wiki" }
+
+  subject(:event_store) { described_class.new(project, old_storage_version: nil, old_disk_path: old_disk_path, old_wiki_disk_path: old_wiki_disk_path) }
+
+  describe '#create' do
+    it 'does not create an event when not running on a primary node' do
+      allow(Gitlab::Geo).to receive(:primary?) { false }
+
+      expect { event_store.create }.not_to change(Geo::HashedStorageMigratedEvent, :count)
+    end
+
+    context 'when running on a primary node' do
+      before do
+        allow(Gitlab::Geo).to receive(:primary?) { true }
+      end
+
+      it 'does not create an event when there are no secondary nodes' do
+        allow(Gitlab::Geo).to receive(:secondary_nodes) { [] }
+
+        expect { subject.create }.not_to change(Geo::HashedStorageMigratedEvent, :count)
+      end
+
+      it 'creates a hashed migration event' do
+        expect { event_store.create }.to change(Geo::HashedStorageMigratedEvent, :count).by(1)
+      end
+
+      it 'tracks project attributes' do
+        event_store.create
+
+        event = Geo::HashedStorageMigratedEvent.last
+
+        expect(event).to have_attributes(
+          repository_storage_name: project.repository_storage,
+          repository_storage_path: project.repository_storage_path,
+          old_storage_version: nil,
+          new_storage_version: project.storage_version,
+          old_disk_path: old_disk_path,
+          new_disk_path: project.disk_path,
+          old_wiki_disk_path: old_wiki_disk_path,
+          new_wiki_disk_path: project.wiki.disk_path
+        )
+      end
+    end
+  end
+end