feat: Add Kafka internal metrics collection

src/Agent/NewRelic/Agent/Core/Agent.cs

@@ -514,6 +514,11 @@ public void RecordCountMetric(string metricName, long count = 1)
         _agentHealthReporter.ReportCountMetric(metricName, count);
     }
 
+    public void RecordGaugeMetric(string metricName, float value)
+    {
+        _agentHealthReporter.ReportGaugeMetric(metricName, value);
+    }
+
     public void RecordByteMetric(string metricName, long totalBytes, long? exclusiveBytes = null)
     {
         _agentHealthReporter.ReportByteMetric(metricName, totalBytes, exclusiveBytes);

src/Agent/NewRelic/Agent/Core/AgentHealth/AgentHealthReporter.cs

@@ -162,6 +162,12 @@ public void ReportByteMetric(string metricName, long totalBytes, long? exclusive
         TrySend(metric);
     }
 
+    public void ReportGaugeMetric(string metricName, float value)
+    {
+        var metric = _metricBuilder.TryBuildGaugeMetric(metricName, value);
+        TrySend(metric);
+    }
+
 
 
     public void ReportDotnetVersion()

src/Agent/NewRelic/Agent/Core/AgentHealth/IAgentHealthReporter.cs

@@ -131,6 +131,7 @@ public interface IAgentHealthReporter : IOutOfBandMetricSource
 
     void ReportSupportabilityCountMetric(string metricName, long count = 1);
     void ReportCountMetric(string metricName, long count = 1);
+    void ReportGaugeMetric(string metricName, float value);
 
     void ReportInfiniteTracingSpanResponseError();
     void ReportInfiniteTracingSpanEventsSeen(long count = 1);

src/Agent/NewRelic/Agent/Core/WireModels/IMetricBuilder.cs

@@ -210,6 +210,7 @@ public interface IMetricBuilder
 
     MetricWireModel TryBuildCountMetric(string metricName, long count);
     MetricWireModel TryBuildByteMetric(string metricName, long totalBytes, long? exclusiveBytes = null);
+    MetricWireModel TryBuildGaugeMetric(string metricName, float value);
 
     MetricWireModel TryBuildDistributedTraceHeadersAcceptedLate(int acceptedLateCount);
 }

src/Agent/NewRelic/Agent/Core/WireModels/MetricWireModel.cs

@@ -1039,6 +1039,12 @@ public MetricWireModel TryBuildByteMetric(string metricName, long totalBytes, lo
             return BuildMetric(_metricNameService, metricName, null, data);
         }
 
+        public MetricWireModel TryBuildGaugeMetric(string metricName, float value)
+        {
+            var data = MetricDataWireModel.BuildGaugeValue(value);
+            return BuildMetric(_metricNameService, metricName, null, data);
+        }
+
         #endregion
     }
 }

src/Agent/NewRelic/Agent/Extensions/NewRelic.Agent.Extensions/Api/Experimental/IAgentExperimental.cs

@@ -25,6 +25,14 @@ public interface IAgentExperimental
     /// <param name="metricName"></param>
     /// <param name="count"></param>
     void RecordCountMetric(string metricName, long count = 1);
+
+    /// <summary>
+    /// Records a gauge metric with the given name, representing a point-in-time value
+    /// </summary>
+    /// <param name="metricName"></param>
+    /// <param name="value"></param>
+    void RecordGaugeMetric(string metricName, float value);
+
     /// <summary>
     /// Records a byte count metric with the given name
     /// </summary>