Auto close related alert issue on recovery

- Limited to prometheus alerts right now

app/services/alert_management/process_prometheus_alert_service.rb

@@ -66,7 +66,11 @@ module AlertManagement
 
     def process_resolved_alert_management_alert
       return if am_alert.blank?
-      return if am_alert.resolve(ends_at)
+
+      if am_alert.resolve(ends_at)
+        close_issue(am_alert.issue)
+        return
+      end
 
       logger.warn(
         message: 'Unable to update AlertManagement::Alert status to resolved',
@@ -75,6 +79,16 @@ module AlertManagement
       )
     end
 
+    def close_issue(issue)
+      return if issue.blank? || issue.closed?
+
+      Issues::CloseService
+        .new(project, User.alert_bot)
+        .execute(issue, system_note: false)
+
+      SystemNoteService.auto_resolve_prometheus_alert(issue, project, User.alert_bot) if issue.reset.closed?
+    end
+
     def logger
       @logger ||= Gitlab::AppLogger
     end

changelogs/unreleased/222253-close-issue-on-resolved-alert.yml

+---
+title: Automatically close related issue when resolving Alert Management Prometheus
+  Alert
+merge_request: 35208
+author:
+type: added

spec/factories/alert_management/alerts.rb

@@ -16,7 +16,9 @@ FactoryBot.define do
     end
 
     trait :with_issue do
-      issue
+      after(:create) do |alert|
+        create(:issue, alert_management_alert: alert, project: alert.project)
+      end
     end
 
     trait :with_assignee do |alert|

spec/requests/api/graphql/project/alert_management/alerts_spec.rb

@@ -78,7 +78,7 @@ RSpec.describe 'getting Alert Management Alerts' do
 
         expect(second_alert).to include(
           'iid' => resolved_alert.iid.to_s,
-          'issueIid' => nil,
+          'issueIid' => resolved_alert.issue_iid.to_s,
           'status' => 'RESOLVED',
           'endedAt' => resolved_alert.ended_at.strftime('%Y-%m-%dT%H:%M:%SZ')
         )

spec/services/alert_management/process_prometheus_alert_service_spec.rb

@@ -123,6 +123,21 @@ RSpec.describe AlertManagement::ProcessPrometheusAlertService do
           it 'resolves an existing alert' do
             expect { execute }.to change { alert.reload.resolved? }.to(true)
           end
+
+          context 'existing issue' do
+            let!(:alert) { create(:alert_management_alert, :with_issue, project: project, fingerprint: parsed_alert.gitlab_fingerprint) }
+
+            it 'closes the issue' do
+              issue = alert.issue
+
+              expect { execute }
+                .to change { issue.reload.state }
+                .from('opened')
+                .to('closed')
+            end
+
+            specify { expect { execute }.to change(Note, :count).by(1) }
+          end
         end
 
         context 'when status change did not succeed' do