Set failed commit status when TeamCity is unreachable

app/models/project_services/teamcity_service.rb

@@ -87,6 +87,11 @@ class TeamcityService < CiService
     response = get_path("httpAuth/app/rest/builds/branch:unspecified:any,revision:#{sha}")
 
     { build_page: read_build_page(response), commit_status: read_commit_status(response) }
+
+  rescue Errno::ECONNREFUSED => e
+    Gitlab::ErrorTracking.log_exception(e, project_id: project_id)
+
+    { build_page: teamcity_url, commit_status: :error }
   end
 
   def execute(data)

changelogs/unreleased/29825-reactivecaching-sidekiq-queue-overloaded-teamcity.yml

+---
+title: Set commit status to failed if the TeamCity connection is refused
+merge_request: 27395
+author:
+type: fixed

spec/models/project_services/teamcity_service_spec.rb

@@ -7,6 +7,7 @@ describe TeamcityService, :use_clean_rails_memory_store_caching do
   include StubRequests
 
   let(:teamcity_url) { 'http://gitlab.com/teamcity' }
+  let(:teamcity_full_url) { 'http://gitlab.com/teamcity/httpAuth/app/rest/builds/branch:unspecified:any,revision:123' }
   let(:project) { create(:project) }
 
   subject(:service) do
@@ -165,6 +166,16 @@ describe TeamcityService, :use_clean_rails_memory_store_caching do
           is_expected.to eq('http://gitlab.com/teamcity/viewLog.html?buildId=666&buildTypeId=foo')
         end
       end
+
+      it 'returns the teamcity_url when teamcity is unreachable' do
+        stub_full_request(teamcity_full_url).to_raise(Errno::ECONNREFUSED)
+
+        expect(Gitlab::ErrorTracking)
+          .to receive(:log_exception)
+          .with(instance_of(Errno::ECONNREFUSED), project_id: project.id)
+
+        is_expected.to eq(teamcity_url)
+      end
     end
 
     context 'commit_status' do
@@ -205,6 +216,16 @@ describe TeamcityService, :use_clean_rails_memory_store_caching do
 
         is_expected.to eq(:error)
       end
+
+      it 'sets commit status to :error when teamcity is unreachable' do
+        stub_full_request(teamcity_full_url).to_raise(Errno::ECONNREFUSED)
+
+        expect(Gitlab::ErrorTracking)
+          .to receive(:log_exception)
+          .with(instance_of(Errno::ECONNREFUSED), project_id: project.id)
+
+        is_expected.to eq(:error)
+      end
     end
   end
 
@@ -300,7 +321,6 @@ describe TeamcityService, :use_clean_rails_memory_store_caching do
   end
 
   def stub_request(status: 200, body: nil, build_status: 'success')
-    teamcity_full_url = 'http://gitlab.com/teamcity/httpAuth/app/rest/builds/branch:unspecified:any,revision:123'
     auth = %w(mic password)
 
     body ||= %Q({"build":{"status":"#{build_status}","id":"666"}})