refactor(tracer): replace class-based env access with functional helpers (#4146)

Co-authored-by: Andrea Amorosi <dreamorosi@gmail.com>

Author: chetan9518

packages/tracer/src/Tracer.ts

@@ -17,13 +17,15 @@ import type {
   HandlerMethodDecorator,
   SyncHandler,
 } from '@aws-lambda-powertools/commons/types';
+import {
+  getServiceName,
+  getStringFromEnv,
+  getXRayTraceIdFromEnv,
+  isRequestXRaySampled,
+} from '@aws-lambda-powertools/commons/utils/env';
 import type { Handler } from 'aws-lambda';
 import type { Segment, Subsegment } from 'aws-xray-sdk-core';
 import xraySdk from 'aws-xray-sdk-core';
-import {
-  type EnvironmentVariablesService,
-  environmentVariablesService,
-} from './config/EnvironmentVariablesService.js';
 import { ProviderService } from './provider/ProviderService.js';
 import type { ConfigServiceInterface } from './types/ConfigServiceInterface.js';
 import type { ProviderServiceInterface } from './types/ProviderService.js';
@@ -174,11 +176,18 @@ class Tracer extends Utility implements TracerInterface {
   private customConfigService?: ConfigServiceInterface;
 
   /**
-   * The environment variables service used by the Tracer, is always initialized in the constructor in setOptions().
+   * Cache environment variables once at init time.
    */
-  private envVarsService!: EnvironmentVariablesService;
+  readonly #envConfig = {
+    awsExecutionEnv: '',
+    samLocal: '',
+    captureError: '',
+    captureHTTPsRequests: '',
+    captureResponse: '',
+    tracingEnabled: '',
+    serviceName: '',
+  };
 
-  // serviceName is always initialized in the constructor in setOptions()
   /**
    * The name of the service, is always initialized in the constructor in setOptions().
    */
@@ -192,6 +201,7 @@ class Tracer extends Utility implements TracerInterface {
   public constructor(options: TracerOptions = {}) {
     super();
 
+    this.#setEnvConfig();
     this.setOptions(options);
     this.provider = new ProviderService();
     if (this.isTracingEnabled() && this.captureHTTPsRequests) {
@@ -581,7 +591,7 @@ class Tracer extends Utility implements TracerInterface {
    * ```
    */
   public getRootXrayTraceId(): string | undefined {
-    return this.envVarsService.getXrayTraceId();
+    return getXRayTraceIdFromEnv();
   }
 
   /**
@@ -628,7 +638,7 @@ class Tracer extends Utility implements TracerInterface {
   public isTraceSampled(): boolean {
     if (!this.isTracingEnabled()) return false;
 
-    return this.envVarsService.getXrayTraceSampled();
+    return isRequestXRaySampled();
   }
 
   /**
@@ -733,39 +743,28 @@ class Tracer extends Utility implements TracerInterface {
     return this.customConfigService;
   }
 
-  /**
-   * Get for `envVarsService`.
-   * Used internally during initialization.
-   */
-  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'
-    );
+    return this.#envConfig.awsExecutionEnv === 'AWS_Lambda_amplify-mock';
   }
 
   /**
    * Determine if we are running in a Lambda execution environment.
    * Used internally during initialization.
    */
   private isLambdaExecutionEnv(): boolean {
-    return this.getEnvVarsService().getAwsExecutionEnv() !== '';
+    return this.#envConfig.awsExecutionEnv !== '';
   }
 
   /**
    * Determine if we are running inside a SAM CLI process.
    * Used internally during initialization.
    */
   private isLambdaSamCli(): boolean {
-    return this.getEnvVarsService().getSamLocal() !== '';
+    return this.#envConfig.samLocal !== '';
   }
 
   /**
@@ -784,10 +783,8 @@ class Tracer extends Utility implements TracerInterface {
       return;
     }
 
-    const envVarsValue = this.getEnvVarsService().getTracingCaptureError();
-    if (envVarsValue.toLowerCase() === 'false') {
+    if (this.#envConfig.captureError.toLowerCase() === 'false') {
       this.captureError = false;
-
       return;
     }
   }
@@ -820,10 +817,8 @@ class Tracer extends Utility implements TracerInterface {
       return;
     }
 
-    const envVarsValue = this.getEnvVarsService().getCaptureHTTPsRequests();
-    if (envVarsValue.toLowerCase() === 'false') {
+    if (this.#envConfig.captureHTTPsRequests.toLowerCase() === 'false') {
       this.captureHTTPsRequests = false;
-
       return;
     }
   }
@@ -844,10 +839,8 @@ class Tracer extends Utility implements TracerInterface {
       return;
     }
 
-    const envVarsValue = this.getEnvVarsService().getTracingCaptureResponse();
-    if (envVarsValue.toLowerCase() === 'false') {
+    if (this.#envConfig.captureResponse.toLowerCase() === 'false') {
       this.captureResponse = false;
-
       return;
     }
   }
@@ -876,7 +869,6 @@ class Tracer extends Utility implements TracerInterface {
     const { enabled, serviceName, captureHTTPsRequests, customConfigService } =
       options;
 
-    this.envVarsService = environmentVariablesService;
     this.setCustomConfigService(customConfigService);
     this.setTracingEnabled(enabled);
     this.setCaptureResponse();
@@ -910,10 +902,11 @@ class Tracer extends Utility implements TracerInterface {
       return;
     }
 
-    const envVarsValue = this.getEnvVarsService().getServiceName();
-    if (envVarsValue !== undefined && this.isValidServiceName(envVarsValue)) {
-      this.serviceName = envVarsValue;
-
+    if (
+      this.#envConfig.serviceName !== undefined &&
+      this.isValidServiceName(this.#envConfig.serviceName)
+    ) {
+      this.serviceName = this.#envConfig.serviceName;
       return;
     }
     this.serviceName = this.defaultServiceName;
@@ -943,10 +936,8 @@ class Tracer extends Utility implements TracerInterface {
       return;
     }
 
-    const envVarsValue = this.getEnvVarsService().getTracingEnabled();
-    if (envVarsValue.toLowerCase() === 'false') {
+    if (this.#envConfig.tracingEnabled.toLowerCase() === 'false') {
       this.tracingEnabled = false;
-
       return;
     }
 
@@ -958,6 +949,38 @@ class Tracer extends Utility implements TracerInterface {
       this.tracingEnabled = false;
     }
   }
+
+  /**
+   * Set environment variables for the tracer.
+   * This method is called during initialization to ensure environment variables are available.
+   */
+  #setEnvConfig(): void {
+    this.#envConfig.awsExecutionEnv = getStringFromEnv({
+      key: 'AWS_EXECUTION_ENV',
+      defaultValue: '',
+    });
+    this.#envConfig.samLocal = getStringFromEnv({
+      key: 'AWS_SAM_LOCAL',
+      defaultValue: '',
+    });
+    this.#envConfig.captureError = getStringFromEnv({
+      key: 'POWERTOOLS_TRACER_CAPTURE_ERROR',
+      defaultValue: '',
+    });
+    this.#envConfig.captureHTTPsRequests = getStringFromEnv({
+      key: 'POWERTOOLS_TRACER_CAPTURE_HTTPS_REQUESTS',
+      defaultValue: '',
+    });
+    this.#envConfig.captureResponse = getStringFromEnv({
+      key: 'POWERTOOLS_TRACER_CAPTURE_RESPONSE',
+      defaultValue: '',
+    });
+    this.#envConfig.tracingEnabled = getStringFromEnv({
+      key: 'POWERTOOLS_TRACE_ENABLED',
+      defaultValue: '',
+    });
+    this.#envConfig.serviceName = getServiceName();
+  }
 }
 
 export { Tracer };

packages/tracer/src/config/EnvironmentVariablesService.ts

@@ -28,7 +28,7 @@ import http from 'node:http';
 import https from 'node:https';
 import { addUserAgentMiddleware } from '@aws-lambda-powertools/commons';
 import type { DiagnosticsChannel } from 'undici-types';
-import { environmentVariablesService } from '../config/EnvironmentVariablesService.js';
+import { getXRayTraceIdFromEnv } from '@aws-lambda-powertools/commons/utils/env';
 import {
   findHeaderAndDecode,
   getRequestURL,
@@ -134,7 +134,7 @@ class ProviderService implements ProviderServiceInterface {
         // @ts-expect-error
         request.addHeader(
           'X-Amzn-Trace-Id',
-          `Root=${environmentVariablesService.getXrayTraceId()};Parent=${subsegment.id};Sampled=${subsegment.notTraced ? '0' : '1'}`
+          `Root=${getXRayTraceIdFromEnv()};Parent=${subsegment.id};Sampled=${subsegment.notTraced ? '0' : '1'}`
         );
 
         (subsegment as HttpSubsegment).http = {