Guard against various Faraday exception response formats

CHANGELOG.asciidoc

@@ -34,6 +34,10 @@ endif::[]
 [[release-notes-4.x]]
 === Ruby Agent version 4.x
 
+[float]
+===== Fixed
+- Guard against various Faraday exception response formats {pull}1428[#1428]
+
 [[release-notes-4.7.0]]
 ==== 4.7.0
 

lib/elastic_apm/spies/faraday.rb

@@ -109,8 +109,14 @@ def run_request(method, url, body, headers, &block)
                   yield req if block
                 end
               rescue Faraday::ClientError, Faraday::ServerError => e # Faraday::Response::RaiseError
-                status = e.response_status if e.respond_to?(:response_status)
-                status ||= e.response&.fetch(:status)
+                status =
+                  if e.respond_to?(:response_status)
+                    e.response_status
+                  elsif e.response && e.response.respond_to?(:status)
+                    e.response.status
+                  elsif e.response && e.response.respond_to?(:fetch)
+                    e.response[:status]
+                  end
                 http = span&.context&.http
                 if http && status
                   http.status_code = status.to_s

spec/elastic_apm/metrics/cpu_mem_set_spec.rb

@@ -46,7 +46,7 @@ module Metrics
               'system.memory.total': 4_042_711_040,
               'system.process.cpu.total.norm.pct': 0.2,
               'system.process.memory.size': 53_223_424,
-              'system.process.memory.rss.bytes': 12_738_560
+              'system.process.memory.rss.bytes': 25_477_120
             )
           end
 
@@ -72,7 +72,7 @@ module Metrics
                 'system.memory.total': 4_042_711_040,
                 'system.process.cpu.total.norm.pct': 0.2,
                 'system.process.memory.size': 53_223_424,
-                'system.process.memory.rss.bytes': 12_738_560
+                'system.process.memory.rss.bytes': 25_477_120
               )
             end
           end
@@ -100,6 +100,8 @@ def mock_proc_files(
         proc_stat_format: :debian,
         proc_meminfo_format: nil
       )
+        allow_any_instance_of(ElasticAPM::Metrics::CpuMemSet::Linux::Meminfo).
+          to receive(:`).with('getconf PAGESIZE').and_return('8192')
         {
           '/proc/stat' =>
             ["proc_stat_#{proc_stat_format}", { user: user, idle: idle }],

spec/elastic_apm/spies/faraday_spec.rb

@@ -198,7 +198,7 @@ module ElasticAPM
         end
       end
 
-      it 'should capture status_code' do
+      it 'captures status_code' do
         WebMock.stub_request(:get, 'http://example.com')
           .to_return(status: [404, 'Not Found'])
 
@@ -217,7 +217,7 @@ module ElasticAPM
         expect(http.status_code).to match('404')
       end
 
-      it 'should handle a nil response' do
+      it 'handles a nil response' do
         WebMock.stub_request(:get, 'http://example.com')
           .to_raise(Faraday::ClientError)
 
@@ -235,6 +235,77 @@ module ElasticAPM
         expect(http.status_code).to be nil
       end
 
+      it 'handles faraday response' do
+        class FaradayErrorWithResponseObject < Faraday::ClientError
+          def response
+            Faraday::Response.new(status: 500)
+          end
+          undef response_status
+        end
+        WebMock.stub_request(:get, 'http://example.com')
+          .to_raise(FaradayErrorWithResponseObject.new(nil))
+
+        with_agent do
+          begin
+            ElasticAPM.with_transaction 'Faraday Middleware test' do
+              client.get('http://example.com')
+            end
+          rescue Faraday::ClientError
+          end
+        end
+        span, = @intercepted.spans
+
+        http = span.context.http
+        expect(http.status_code).to eq('500')
+      end
+
+      it 'handles faraday response hash' do
+        class FaradayErrorWithResponseHash < Faraday::ClientError
+          def response
+            { status: 500 }
+          end
+          undef response_status
+        end
+        WebMock.stub_request(:get, 'http://example.com')
+          .to_raise(FaradayErrorWithResponseHash.new(nil))
+
+        with_agent do
+          begin
+            ElasticAPM.with_transaction 'Faraday Middleware test' do
+              client.get('http://example.com')
+            end
+          rescue Faraday::ClientError
+          end
+        end
+        span, = @intercepted.spans
+
+        http = span.context.http
+        expect(http.status_code).to eq('500')
+      end
+
+      it 'does not raise error when response is string' do
+        class FaradayErrorWithResponseString < Faraday::ClientError
+          def response
+            'whatever'
+          end
+          undef response_status
+        end
+        WebMock.stub_request(:get, 'http://example.com')
+          .to_raise(FaradayErrorWithResponseString.new(nil))
+
+        with_agent do
+          begin
+            ElasticAPM.with_transaction 'Faraday Middleware test' do
+              client.get('http://example.com')
+            end
+          rescue Faraday::ClientError
+          end
+        end
+        span, = @intercepted.spans
+
+        http = span.context.http
+        expect(http.status_code).to be nil
+      end
     end
   end
 end