Added specs

lib/gitlab/prometheus.rb

@@ -49,11 +49,11 @@ module Gitlab
     end
 
     def get(url)
-      begin
-        handle_response(HTTParty.get(url))
-      rescue SocketError
-        raise PrometheusError, "Can't connect to #{url}"
-      end
+      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"
     end
 
     def handle_response(response)

spec/lib/gitlab/prometheus_spec.rb

@@ -49,6 +49,24 @@ describe Gitlab::Prometheus, lib: true do
     end
   end
 
+  describe 'failure to reach a prometheus url' do
+    prometheus_invalid_url = 'https://prometheus.invalid.example.com'
+
+    it 'raises a Gitlab::PrometheusError error when a SocketError is rescued' do
+      req_stub = stub_prometheus_request_with_socket_exception(prometheus_invalid_url)
+
+      expect { subject.send(:get, prometheus_invalid_url) }.to raise_error(Gitlab::PrometheusError, "Can't connect to #{prometheus_invalid_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_ssl_exception(prometheus_invalid_url)
+
+      expect { subject.send(:get, prometheus_invalid_url) }.to raise_error(Gitlab::PrometheusError, "#{prometheus_invalid_url} contains invalid SSL data")
+      expect(req_stub).to have_been_requested
+    end
+  end
+
   describe '#query' do
     let(:prometheus_query) { prometheus_cpu_query('env-slug') }
     let(:query_url) { prometheus_query_url(prometheus_query) }

spec/support/prometheus_helpers.rb

@@ -33,6 +33,16 @@ module PrometheusHelpers
       })
   end
 
+  def stub_prometheus_request_with_socket_exception(url)
+    WebMock.stub_request(:get, url)
+      .to_raise(SocketError)
+  end
+
+  def stub_prometheus_request_with_ssl_exception(url)
+    WebMock.stub_request(:get, url)
+      .to_raise(OpenSSL::SSL::SSLError)
+  end
+
   def stub_all_prometheus_requests(environment_slug, body: nil, status: 200)
     stub_prometheus_request(
       prometheus_query_url(prometheus_memory_query(environment_slug)),