improv(tracer): set AWS_XRAY_CONTEXT_MISSING to IGNORE_ERROR when no value is set (#3058)

Author: dreamorosi

packages/tracer/src/Tracer.ts

@@ -1,3 +1,15 @@
+/**
+ * If the AWS_XRAY_CONTEXT_MISSING environment variable is not set, we set it to IGNORE_ERROR.
+ *
+ * This is to prevent the AWS X-Ray SDK from logging errors when using top-level await features that make HTTP requests.
+ * For example, when using the Parameters utility to fetch parameters during the initialization of the Lambda handler - See #2046
+ */
+if (
+  process.env.AWS_XRAY_CONTEXT_MISSING === '' ||
+  process.env.AWS_XRAY_CONTEXT_MISSING === undefined
+) {
+  process.env.AWS_XRAY_CONTEXT_MISSING = 'IGNORE_ERROR';
+}
 import { Utility } from '@aws-lambda-powertools/commons';
 import type {
   AsyncHandler,

packages/tracer/tests/unit/Tracer.test.ts

@@ -59,6 +59,13 @@ describe('Class: Tracer', () => {
   });
 
   describe('Method: constructor', () => {
+    it('sets the AWS_XRAY_CONTEXT_MISSING environment variable to IGNORE_ERROR when it is not set', () => {
+      // We are setting the environment variable as a side effect of importing the module, setting it within the Tracer would
+      // require introducing async code to the constructor, which is not a good practice, in order to lazy load the AWS X-Ray SDK for Node.js
+      // on demand. Between that option, and setting it as a side effect of importing the module, the latter is the better option.
+      expect(process.env.AWS_XRAY_CONTEXT_MISSING).toBe('IGNORE_ERROR');
+    });
+
     it('instantiates with default settings when no option is passed', () => {
       // Prepare & Act
       const tracer = new Tracer(undefined);