Remove spans with ec2 metadata ip address from metrics (#150)

*Issue #, if available:*
ADOT SDK resource detectors by default have enabled a few AWS resource
detector which will call EC2 metadata API endpoints. These activities
have been captured by auto-instrumentation and generated AppSignals
metrics.

*Description of changes:*
Suppress AwsSpanMetricsProcessor from generating metrics when the
RemoteService points to 169.254.169.254

*Testing*:
Tested using Java Adot:
aws-observability/aws-otel-java-instrumentation#1015

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copy, and redistribute this contribution, under the terms of your
choice.

Author: harrryr

aws-distro-opentelemetry-node-autoinstrumentation/src/aws-span-metrics-processor.ts

@@ -7,6 +7,7 @@ import { ReadableSpan, Span, SpanProcessor } from '@opentelemetry/sdk-trace-base
 import { SEMATTRS_HTTP_STATUS_CODE } from '@opentelemetry/semantic-conventions';
 import { AttributeMap, MetricAttributeGenerator } from './metric-attribute-generator';
 import { ForceFlushFunction } from './aws-span-processing-util';
+import { AWS_ATTRIBUTE_KEYS } from './aws-attribute-keys';
 
 /**
  * This processor will generate metrics based on span data. It depends on a
@@ -33,6 +34,10 @@ export class AwsSpanMetricsProcessor implements SpanProcessor {
   private FAULT_CODE_LOWER_BOUND: number = 500;
   private FAULT_CODE_UPPER_BOUND: number = 599;
 
+  // EC2 Metadata API IP Address
+  // https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html#instancedata-inside-access
+  private EC2_METADATA_API_IP: string = '169.254.169.254';
+
   // Metric instruments
   private errorHistogram: Histogram;
   private faultHistogram: Histogram;
@@ -130,7 +135,7 @@ export class AwsSpanMetricsProcessor implements SpanProcessor {
 
   private recordMetrics(span: ReadableSpan, attributes: Attributes): void {
     // Only record metrics if non-empty attributes are returned.
-    if (Object.keys(attributes).length > 0) {
+    if (Object.keys(attributes).length > 0 && !this.isEc2MetadataApiSpan(attributes)) {
       this.recordErrorOrFault(span, attributes);
       this.recordLatency(span, attributes);
     }
@@ -143,4 +148,8 @@ export class AwsSpanMetricsProcessor implements SpanProcessor {
   public forceFlush(): Promise<void> {
     return this.forceFlushFunction();
   }
+
+  private isEc2MetadataApiSpan(attributes: Attributes): boolean {
+    return attributes[AWS_ATTRIBUTE_KEYS.AWS_REMOTE_SERVICE] === this.EC2_METADATA_API_IP;
+  }
 }

aws-distro-opentelemetry-node-autoinstrumentation/test/aws-span-metrics-processor.test.ts

@@ -397,6 +397,22 @@ describe('AwsSpanMetricsProcessorTest', () => {
     validateMetricsGeneratedForStatusDataOk(600, ExpectedStatusMetric.NEITHER);
   });
 
+  it('testOnEndMetricsGenerationFromEc2MetadataApi', () => {
+    const spanAttributes: Attributes = { [AWS_ATTRIBUTE_KEYS.AWS_REMOTE_SERVICE]: '169.254.169.254' };
+    const readableSpanMock: ReadableSpan = buildReadableSpanMock(
+      spanAttributes,
+      SpanKind.CLIENT,
+      INVALID_SPAN_CONTEXT,
+      { code: SpanStatusCode.UNSET }
+    );
+    const metricAttributesMap: AttributeMap = buildEc2MetadataApiMetricAttributes();
+    configureMocksForOnEnd(readableSpanMock, metricAttributesMap);
+    awsSpanMetricsProcessor.onEnd(readableSpanMock);
+    sinon.assert.notCalled(errorHistogramMockRecord);
+    sinon.assert.notCalled(faultHistogramMockRecord);
+    sinon.assert.notCalled(latencyHistogramMockRecord);
+  });
+
   function buildSpanAttributes(containsAttribute: boolean): Attributes {
     if (containsAttribute) {
       return { 'original key': 'original value' };
@@ -421,6 +437,13 @@ describe('AwsSpanMetricsProcessorTest', () => {
     return attributesMap;
   }
 
+  function buildEc2MetadataApiMetricAttributes(): AttributeMap {
+    const attributesMap: AttributeMap = {};
+    const attributes: Attributes = { [AWS_ATTRIBUTE_KEYS.AWS_REMOTE_SERVICE]: '169.254.169.254' };
+    attributesMap[DEPENDENCY_METRIC] = attributes;
+    return attributesMap;
+  }
+
   function buildReadableSpanMock(
     spanAttributes: Attributes,
     spanKind: SpanKind = SpanKind.SERVER,