feat: add logging about export status to Metrics

exporter/otlp-metrics/lib/opentelemetry/exporter/otlp/metrics/metrics_exporter.rb

@@ -82,10 +82,21 @@ def pull
             export(collect)
           end
 
+          def report_result(result_code, metrics)
+            if result_code == SUCCESS
+              OpenTelemetry.logger.debug('Successfully exported metrics')
+            else
+              OpenTelemetry.handle_error(exception: OpenTelemetry::SDK::Metrics::Export::ExportError.new('Unable to export metrics'))
+              OpenTelemetry.logger.error("Result code: #{result_code}")
+            end
+          end
+
           # metrics Array[MetricData]
           def export(metrics, timeout: nil)
             @mutex.synchronize do
-              send_bytes(encode(metrics), timeout: timeout)
+              result = send_bytes(encode(metrics), timeout: timeout)
+              report_result(result, metrics)
+              result
             end
           end
 

exporter/otlp-metrics/test/opentelemetry/exporter/otlp/metrics/metrics_exporter_test.rb

@@ -437,6 +437,38 @@
       _(result).must_equal(METRICS_SUCCESS)
     end
 
+    it 'logs successful export at debug level' do
+      log_stream = StringIO.new
+      logger = OpenTelemetry.logger
+      OpenTelemetry.logger = ::Logger.new(log_stream)
+      OpenTelemetry.logger.level = ::Logger::DEBUG
+
+      stub_request(:post, 'http://localhost:4318/v1/metrics').to_return(status: 200)
+
+      metrics_data = create_metrics_data
+      result = exporter.export([metrics_data])
+      _(log_stream.string).must_match(/DEBUG -- : Successfully exported metrics/)
+      _(result).must_equal(METRICS_SUCCESS)
+    ensure
+      OpenTelemetry.logger = logger
+    end
+
+    it 'logs failure to export at error level' do
+      log_stream = StringIO.new
+      logger = OpenTelemetry.logger
+      OpenTelemetry.logger = ::Logger.new(log_stream)
+
+      stub_request(:post, 'http://localhost:4318/v1/metrics').to_return(status: 500)
+
+      metrics_data = create_metrics_data
+      result = exporter.export([metrics_data])
+      _(log_stream.string).must_match(/ERROR -- : OpenTelemetry error: Unable to export metrics/)
+      _(log_stream.string).must_match(/ERROR -- : Result code: 1/)
+      _(result).must_equal(METRICS_FAILURE)
+    ensure
+      OpenTelemetry.logger = logger
+    end
+
     it 'handles encoding errors with poise and grace' do
       log_stream = StringIO.new
       logger = OpenTelemetry.logger