feat(tracer): auto disable when running inside amplify mock (#1010)

* feat: disable tracer when running in amplify mock

* chore: housekeeping typo

Author: dreamorosi

Diff for: docs/core/tracer.md

@@ -65,7 +65,7 @@ For a **complete list** of supported environment variables, refer to [this secti
 
 #### Example using AWS Serverless Application Model (SAM)
 
-The `Tracer` utility is instantiated outside of the Lambda handler. In doing this, the same instance can be used across multiple invocations inside the same execution environment. This allows `Metrics` to be aware of things like whether or not a given invocation had a cold start or not.
+The `Tracer` utility is instantiated outside of the Lambda handler. In doing this, the same instance can be used across multiple invocations inside the same execution environment. This allows `Tracer` to be aware of things like whether or not a given invocation had a cold start or not.
 
 === "handler.ts"
 

Diff for: packages/tracer/src/Tracer.ts

@@ -597,6 +597,14 @@ class Tracer extends Utility implements TracerInterface {
   private getEnvVarsService(): EnvironmentVariablesService {
     return this.envVarsService;
   }
+
+  /**
+   * Determine if we are running inside an Amplify CLI process.
+   * Used internally during initialization.
+   */
+  private isAmplifyCli(): boolean {
+    return this.getEnvVarsService().getAwsExecutionEnv() === 'AWS_Lambda_amplify-mock';
+  }
 
   /**
    * Determine if we are running in a Lambda execution environment.
@@ -795,7 +803,7 @@ class Tracer extends Utility implements TracerInterface {
       return;
     }
 
-    if (this.isLambdaSamCli() || !this.isLambdaExecutionEnv()) {
+    if (this.isAmplifyCli() || this.isLambdaSamCli() || !this.isLambdaExecutionEnv()) {
       this.tracingEnabled = false;
     }
   }

Diff for: packages/tracer/tests/unit/helpers.test.ts

@@ -204,6 +204,20 @@ describe('Helper: createTracer function', () => {
 
   describe('Environment Variables configs', () => {
 
+    test('when AWS_EXECUTION_ENV environment variable is equal to AWS_Lambda_amplify-mock, tracing is disabled', () => {
+      // Prepare
+      process.env.AWS_EXECUTION_ENV = 'AWS_Lambda_amplify-mock';
+
+      // Act
+      const tracer = createTracer();
+
+      // Assess
+      expect(tracer).toEqual(expect.objectContaining({
+        tracingEnabled: false,
+      }));
+
+    });
+
     test('when AWS_SAM_LOCAL environment variable is set, tracing is disabled', () => {
       // Prepare
       process.env.AWS_SAM_LOCAL = 'true';