Catch unhandled exceptions in health checks

changelogs/unreleased/ak-unhandled-exception-in-health-checks.yml

+---
+title: Catch unhandled exceptions in health checks
+merge_request: 17694
+author:
+type: fixed

lib/gitlab/health_checks/simple_abstract_check.rb

@@ -14,6 +14,8 @@ module Gitlab
         else
           HealthChecks::Result.new(false, "unexpected #{human_name} check result: #{check_result}")
         end
+      rescue => e
+        HealthChecks::Result.new(false, "unexpected #{human_name} check result: #{e}")
       end
 
       def metrics

spec/lib/gitlab/health_checks/simple_check_shared.rb

@@ -57,5 +57,13 @@ shared_context 'simple_check' do |metrics_prefix, check_name, success_result|
 
       it { is_expected.to have_attributes(success: false, message: "#{described_class.human_name} check timed out") }
     end
+
+    context 'Check is raising an unhandled exception' do
+      before do
+        allow(described_class).to receive(:check ).and_raise "unexpected error"
+      end
+
+      it { is_expected.to have_attributes(success: false, message: "unexpected #{described_class.human_name} check result: unexpected error") }
+    end
   end
 end