Remove spans with ec2 metadata ip address from metrics (#172)

Author: harrryr

src/AWS.Distro.OpenTelemetry.AutoInstrumentation/AwsSpanMetricsProcessor.cs

@@ -6,6 +6,7 @@
 using OpenTelemetry;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Resources;
+using static AWS.Distro.OpenTelemetry.AutoInstrumentation.AwsAttributeKeys;
 using static AWS.Distro.OpenTelemetry.AutoInstrumentation.AwsSpanProcessingUtil;
 
 namespace AWS.Distro.OpenTelemetry.AutoInstrumentation;
@@ -32,6 +33,8 @@ public class AwsSpanMetricsProcessor : BaseProcessor<Activity>
     private const int FaultCodeLowerBound = 500;
     private const int FaultCodeUpperBound = 599;
 
+    private const string Ec2MetadataApiIp = "169.254.169.254";
+
     // Metric instruments
     private Histogram<long> errorHistogram;
     private Histogram<long> faultHistogram;
@@ -162,10 +165,21 @@ private void RecordLatency(Activity span, ActivityTagsCollection attributes)
     private void RecordMetrics(Activity span, ActivityTagsCollection attributes)
     {
         // Only record metrics if non-empty attributes are returned.
-        if (attributes.Count > 0)
+        if (attributes.Count > 0 && !IsEc2MetadataApiSpan(attributes))
         {
             this.RecordErrorOrFault(span, attributes);
             this.RecordLatency(span, attributes);
         }
     }
+
+    private bool IsEc2MetadataApiSpan(ActivityTagsCollection attributes)
+    {
+        if (attributes.TryGetValue(AttributeAWSRemoteService, out object? value) &&
+            value is string ip &&
+            ip == Ec2MetadataApiIp)
+        {
+            return true;
+        }
+        return false;
+    }
 }

test/AWS.Distro.OpenTelemetry.AutoInstrumentation.Tests/AwsSpanMetricsProcessorTest.cs

@@ -325,6 +325,18 @@ public void TestOnEndMetricsGenerationWithStatusDataOk()
         this.ValidateMetricsGeneratedForStatusDataOk(600, ExpectedStatusMetric.NEITHER);
     }
 
+    [Fact]
+    public void TestOnEndMetricsGenerationFromEc2MetadataApi()
+    {
+        Activity? spanDataMock = this.activitySource.StartActivity("test", ActivityKind.Client);
+        this.SetLatency(spanDataMock);
+        Dictionary<string, ActivityTagsCollection> expectAttributes = this.BuildEc2MetadataApiMetricAttributes();
+        this.generator.Setup(g => g.GenerateMetricAttributeMapFromSpan(spanDataMock, this.resource))
+            .Returns(expectAttributes);
+        this.awsSpanMetricsProcessor.OnEnd(spanDataMock);
+        this.VerifyHistogramRecords(expectAttributes, 0, 0);
+    }
+
     private void ValidateMetricsGeneratedForAttributeStatusCode(
         int? awsStatusCode, ExpectedStatusMetric expectedStatusMetric)
     {
@@ -524,6 +536,13 @@ private Dictionary<string, ActivityTagsCollection> BuildMetricAttributes(bool co
         return attributes;
     }
 
+    private Dictionary<string, ActivityTagsCollection> BuildEc2MetadataApiMetricAttributes()
+    {
+        Dictionary<string, ActivityTagsCollection> attributes = new Dictionary<string, ActivityTagsCollection>();
+        attributes.Add(MetricAttributeGeneratorConstants.DependencyMetric, new ActivityTagsCollection([new KeyValuePair<string, object?>(AttributeAWSRemoteService, "169.254.169.254")]));
+        return attributes;
+    }
+
     // Configure latency
     private void SetLatency(Activity? spanDataMock, double latency = -1)
     {