Expire relevant ETag caches for realtime_changes endpoints

* ensure that updating import status will flush relevant cache

Changelog: fixed

app/controllers/import/base_controller.rb

@@ -70,7 +70,7 @@ class Import::BaseController < ApplicationController
   end
 
   def already_added_projects
-    @already_added_projects ||= filtered(find_already_added_projects(provider_name))
+    @already_added_projects ||= find_already_added_projects(provider_name)
   end
 
   # rubocop: disable CodeReuse/ActiveRecord

app/models/project_import_state.rb

@@ -38,6 +38,16 @@ class ProjectImportState < ApplicationRecord
     state :finished
     state :failed
 
+    after_transition any => any do |state|
+      realtime_changes_path = Gitlab::Routing.url_helpers.polymorphic_path([:realtime_changes_import, state.project.import_type.to_sym], format: :json) rescue nil
+
+      if realtime_changes_path
+        Gitlab::EtagCaching::Store.new.tap do |store|
+          store.touch(realtime_changes_path)
+        end
+      end
+    end
+
     after_transition [:none, :finished, :failed] => :scheduled do |state, _|
       state.run_after_commit do
         job_id = project.add_import_job

lib/gitlab/github_import/object_counter.rb

@@ -24,6 +24,8 @@ module Gitlab
 
           increment_project_counter(project, object_type, operation, integer)
           increment_global_counter(object_type, operation, integer)
+
+          expire_etag_cache(project.import_type)
         end
 
         def summary(project)
@@ -42,6 +44,16 @@ module Gitlab
 
         private
 
+        def expire_etag_cache(import_type)
+          realtime_changes_path = Gitlab::Routing.url_helpers.polymorphic_path([:realtime_changes_import, import_type.to_sym], format: :json) rescue nil
+
+          if realtime_changes_path
+            Gitlab::EtagCaching::Store.new.tap do |store|
+              store.touch(realtime_changes_path)
+            end
+          end
+        end
+
         # Global counters are long lived, in Prometheus,
         # and it's used to report the health of the Github Importer
         # in the Grafana Dashboard

spec/lib/gitlab/github_import/object_counter_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::GithubImport::ObjectCounter, :clean_gitlab_redis_cache do
-  let_it_be(:project) { create(:project) }
+  let_it_be(:project) { create(:project, import_type: 'github') }
 
   it 'validates the operation being incremented' do
     expect { described_class.increment(project, :issue, :unknown) }
@@ -49,4 +49,12 @@ RSpec.describe Gitlab::GithubImport::ObjectCounter, :clean_gitlab_redis_cache do
       'imported' => {}
     })
   end
+
+  it 'expires etag cache of relevant realtime change endpoints on increment' do
+    expect_next_instance_of(Gitlab::EtagCaching::Store) do |instance|
+      expect(instance).to receive(:touch).with(Gitlab::Routing.url_helpers.realtime_changes_import_github_path(format: :json))
+    end
+
+    described_class.increment(project, :issue, :fetched)
+  end
 end

spec/models/project_import_state_spec.rb

@@ -115,6 +115,46 @@ RSpec.describe ProjectImportState, type: :model do
   end
 
   describe 'import state transitions' do
+    context 'state transition: any => any' do
+      context 'when project import type has realtime changes endpoint' do
+        before do
+          import_state.project.import_type = 'github'
+        end
+
+        it 'expires revelant etag cache' do
+          described_class.state_machines[:status].states.each do |initial_state|
+            import_state.status = initial_state.name
+
+            import_state.status_transitions.each do |transition|
+              expect_next_instance_of(Gitlab::EtagCaching::Store) do |instance|
+                expect(instance).to receive(:touch).with(Gitlab::Routing.url_helpers.realtime_changes_import_github_path(format: :json))
+              end
+
+              transition.perform
+            end
+          end
+        end
+      end
+
+      context 'when project import type has no realtime changes endpoint' do
+        before do
+          import_state.project.import_type = 'jira'
+        end
+
+        it 'does not touch etag caches' do
+          described_class.state_machines[:status].states.each do |initial_state|
+            import_state.status = initial_state.name
+
+            import_state.status_transitions.each do |transition|
+              expect(Gitlab::EtagCaching::Store).not_to receive(:new)
+
+              transition.perform
+            end
+          end
+        end
+      end
+    end
+
     context 'state transition: [:started] => [:finished]' do
       let(:after_import_service) { spy(:after_import_service) }
       let(:housekeeping_service) { spy(:housekeeping_service) }