Merge branch 'prometheus-integration-test-setting-fix' into 'master'

Added rescue block for the test method for the prometheus service

Closes #31451

See merge request !10994

changelogs/unreleased/prometheus-integration-test-setting-fix.yml

+---
+title: Prevent 500 errors caused by testing the Prometheus service
+merge_request: 10994
+author:

lib/gitlab/prometheus.rb

@@ -50,6 +50,12 @@ module Gitlab
     def get(url)
       handle_response(HTTParty.get(url))
+    rescue SocketError
+      raise PrometheusError, "Can't connect to #{url}"
+    rescue OpenSSL::SSL::SSLError
+      raise PrometheusError, "#{url} contains invalid SSL data"
+    rescue HTTParty::Error
+      raise PrometheusError, "Network connection error"
     end
     def handle_response(response)

spec/lib/gitlab/prometheus_spec.rb

@@ -49,6 +49,36 @@ describe Gitlab::Prometheus, lib: true do
     end
   end
+  describe 'failure to reach a provided prometheus url' do
+    let(:prometheus_url) {"https://prometheus.invalid.example.com"}
+
+    context 'exceptions are raised' do
+      it 'raises a Gitlab::PrometheusError error when a SocketError is rescued' do
+        req_stub = stub_prometheus_request_with_exception(prometheus_url, SocketError)
+
+        expect { subject.send(:get, prometheus_url) }
+          .to raise_error(Gitlab::PrometheusError, "Can't connect to #{prometheus_url}")
+        expect(req_stub).to have_been_requested
+      end
+
+      it 'raises a Gitlab::PrometheusError error when a SSLError is rescued' do
+        req_stub = stub_prometheus_request_with_exception(prometheus_url, OpenSSL::SSL::SSLError)
+
+        expect { subject.send(:get, prometheus_url) }
+          .to raise_error(Gitlab::PrometheusError, "#{prometheus_url} contains invalid SSL data")
+        expect(req_stub).to have_been_requested
+      end
+
+      it 'raises a Gitlab::PrometheusError error when a HTTParty::Error is rescued' do
+        req_stub = stub_prometheus_request_with_exception(prometheus_url, HTTParty::Error)
+
+        expect { subject.send(:get, prometheus_url) }
+          .to raise_error(Gitlab::PrometheusError, "Network connection error")
+        expect(req_stub).to have_been_requested
+      end
+    end
+  end
+
   describe '#query' do
     let(:prometheus_query) { prometheus_cpu_query('env-slug') }
     let(:query_url) { prometheus_query_url(prometheus_query) }

spec/models/project_services/prometheus_service_spec.rb

@@ -94,7 +94,7 @@ describe PrometheusService, models: true, caching: true do
     [404, 500].each do |status|
       context "when Prometheus responds with #{status}" do
         before do
-          stub_all_prometheus_requests(environment.slug, status: status, body: 'QUERY FAILED!')
+          stub_all_prometheus_requests(environment.slug, status: status, body: "QUERY FAILED!")
         end
         it { is_expected.to eq(success: false, result: %(#{status} - "QUERY FAILED!")) }

spec/support/prometheus_helpers.rb

@@ -33,6 +33,10 @@ module PrometheusHelpers
       })
   end
+  def stub_prometheus_request_with_exception(url, exception_type)
+    WebMock.stub_request(:get, url).to_raise(exception_type)
+  end
+
   def stub_all_prometheus_requests(environment_slug, body: nil, status: 200)
     stub_prometheus_request(
       prometheus_query_url(prometheus_memory_query(environment_slug)),