feat(all): moved EnvService to commons + exposed getXrayTraceId in tracer (aws-powertools#1123)

* feat: moved EnvService to commons + exposed getXrayTraceId in tracer

* docs: added docs section for getRootXrayTraceId

* Update docs/core/tracer.md

Co-authored-by: Josh Kellendonk <[email protected]>

* fix: remove reduntant methods

* chore: updated unit test case

Co-authored-by: Josh Kellendonk <[email protected]>

Author: dreamorosi

docs/core/tracer.md

@@ -484,6 +484,38 @@ Use **`POWERTOOLS_TRACER_CAPTURE_ERROR=false`** environment variable to instruct
 
     1. You might **return sensitive** information from errors, stack traces you might not control
 
+### Access AWS X-Ray Root Trace ID
+
+Tracer exposes a `getRootXrayTraceId()` method that allows you to retrieve the [AWS X-Ray Root Trace ID](https://docs.aws.amazon.com/xray/latest/devguide/xray-concepts.html#xray-concepts-traces) corresponds to the current function execution.
+
+!!! info "This is commonly useful in two scenarios"
+
+    1. By including the root trace id in your response, consumers can use it to correlate requests
+    2. You might want to surface the root trace id to your end users so that they can reference it while contacting customer service
+
+=== "index.ts"
+
+    ```typescript hl_lines="9"
+    import { Tracer } from '@aws-lambda-powertools/tracer';
+
+    const tracer = new Tracer({ serviceName: 'serverlessAirline' });
+    
+    export const handler = async (event: unknown, context: Context): Promise<void> => {
+        try {
+        ...
+        } catch (err) {
+            const rootTraceId = tracer.getRootXrayTraceId();
+   
+            // Example of returning an error response
+            return {
+                statusCode: 500,
+                body: `Internal Error - Please contact support and quote the following id: ${rootTraceId}`,
+                headers: { "_X_AMZN_TRACE_ID": rootTraceId },
+            };
+        }
+    };
+    ```
+
 ### Escape hatch mechanism
 
 You can use `tracer.provider` attribute to access all methods provided by the [AWS X-Ray SDK](https://docs.aws.amazon.com/xray-sdk-for-nodejs/latest/reference/AWSXRay.html).

layer-publisher/tests/unit/__snapshots__/layer-publisher.test.ts.snap

@@ -32,7 +32,7 @@ Object {
           "S3Bucket": Object {
             "Fn::Sub": "cdk-hnb659fds-assets-\${AWS::AccountId}-\${AWS::Region}",
           },
-          "S3Key": "c2f621503b147cecccf2e6cc6df420a8f11ee29ae042d2c1f523cf5db3f47ca2.zip",
+          "S3Key": "dbdb3f66eaeed03649521bf73dbcdd95a713086afccbac3f57fa407ffb76bdaa.zip",
         },
         "Description": "Lambda Powertools for TypeScript version 1.0.1",
         "LayerName": "AWSLambdaPowertoolsTypeScript",

packages/commons/src/config/ConfigService.ts

@@ -0,0 +1,31 @@
+/**
+ * Abstract class ConfigService
+ *
+ * This class defines common methods and variables that can be set by the developer
+ * in the runtime.
+ *
+ * @class
+ * @abstract
+ */
+abstract class ConfigService {
+
+  /**
+   * It returns the value of an environment variable that has given name.
+   *
+   * @param {string} name
+   * @returns {string}
+   */
+  public abstract get(name: string): string;
+
+  /**
+   * It returns the value of the POWERTOOLS_SERVICE_NAME environment variable.
+   *
+   * @returns {string}
+   */
+  public abstract getServiceName(): string;
+
+}
+
+export {
+  ConfigService,
+};

packages/commons/src/config/EnvironmentVariablesService.ts

@@ -0,0 +1,67 @@
+import { ConfigService } from '.';
+
+/**
+ * Class EnvironmentVariablesService
+ *
+ * This class is used to return environment variables that are available in the runtime of
+ * the current Lambda invocation.
+ * These variables can be a mix of runtime environment variables set by AWS and
+ * variables that can be set by the developer additionally.
+ *
+ * @class
+ * @extends {ConfigService}
+ * @see https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html#configuration-envvars-runtime
+ * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/#environment-variables
+ */
+class EnvironmentVariablesService extends ConfigService {
+
+  /**
+   * @see https://awslabs.github.io/aws-lambda-powertools-typescript/latest/#environment-variables
+   * @protected
+   */
+  protected serviceNameVariable = 'POWERTOOLS_SERVICE_NAME';
+  // Reserved environment variables
+  private xRayTraceIdVariable = '_X_AMZN_TRACE_ID';
+
+  /**
+   * It returns the value of an environment variable that has given name.
+   *
+   * @param {string} name
+   * @returns {string}
+   */
+  public get(name: string): string {
+    return process.env[name]?.trim() || '';
+  }
+
+  /**
+   * It returns the value of the POWERTOOLS_SERVICE_NAME environment variable.
+   *
+   * @returns {string}
+   */
+  public getServiceName(): string {
+    return this.get(this.serviceNameVariable);
+  }
+
+  /**
+   * It returns the value of the _X_AMZN_TRACE_ID environment variable.
+   * 
+   * The AWS X-Ray Trace data available in the environment variable has this format:
+   * `Root=1-5759e988-bd862e3fe1be46a994272793;Parent=557abcec3ee5a047;Sampled=1`,
+   *
+   * The actual Trace ID is: `1-5759e988-bd862e3fe1be46a994272793`.
+   *
+   * @returns {string}
+   */
+  public getXrayTraceId(): string | undefined {
+    const xRayTraceId = this.get(this.xRayTraceIdVariable);
+
+    if (xRayTraceId === '') return undefined;
+
+    return xRayTraceId.split(';')[0].replace('Root=', '');
+  }
+
+}
+
+export {
+  EnvironmentVariablesService,
+};

packages/commons/src/config/index.ts

@@ -0,0 +1,2 @@
+export * from './ConfigService';
+export * from './EnvironmentVariablesService';

packages/commons/src/index.ts

@@ -1,4 +1,5 @@
 export * from './utils/lambda';
 export * from './Utility';
+export * from './config';
 export * as ContextExamples from './samples/resources/contexts';
 export * as Events from './samples/resources/events';

packages/commons/tests/unit/config/EnvironmentVariablesService.test.ts

@@ -0,0 +1,113 @@
+/**
+ * Test EnvironmentVariablesService class
+ *
+ * @group unit/commons/all
+ */
+
+import { EnvironmentVariablesService } from '../../../src/config';
+
+describe('Class: EnvironmentVariablesService', () => {
+
+  const ENVIRONMENT_VARIABLES = process.env;
+
+  beforeEach(() => {
+    jest.resetModules();
+    process.env = { ...ENVIRONMENT_VARIABLES };
+  });
+
+  afterAll(() => {
+    process.env = ENVIRONMENT_VARIABLES;
+  });
+
+  describe('Method: get', () => {
+
+    test('When the variable IS present, it returns the value of a runtime variable', () => {
+
+      // Prepare
+      process.env.CUSTOM_VARIABLE = 'my custom value';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.get('CUSTOM_VARIABLE');
+
+      // Assess
+      expect(value).toEqual('my custom value');
+
+    });
+
+    test('When the variable IS NOT present, it returns an empty string', () => {
+
+      // Prepare
+      delete process.env.CUSTOM_VARIABLE;
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.get('CUSTOM_VARIABLE');
+
+      // Assess
+      expect(value).toEqual('');
+
+    });
+
+  });
+
+  describe('Method: getServiceName', () => {
+
+    test('It returns the value of the environment variable POWERTOOLS_SERVICE_NAME', () => {
+
+      // Prepare
+      process.env.POWERTOOLS_SERVICE_NAME = 'shopping-cart-api';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getServiceName();
+
+      // Assess
+      expect(value).toEqual('shopping-cart-api');
+    });
+
+  });
+
+  describe('Method: getXrayTraceId', () => {
+
+    test('It returns the value of the environment variable _X_AMZN_TRACE_ID', () => {
+
+      // Prepare
+      process.env._X_AMZN_TRACE_ID = 'abcd123456789';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getXrayTraceId();
+
+      // Assess
+      expect(value).toEqual('abcd123456789');
+    });
+    test('It returns the value of the Root X-Ray segment ID properly formatted', () => {
+
+      // Prepare
+      process.env._X_AMZN_TRACE_ID = 'Root=1-5759e988-bd862e3fe1be46a994272793;Parent=557abcec3ee5a047;Sampled=1';
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getXrayTraceId();
+
+      // Assess
+      expect(value).toEqual('1-5759e988-bd862e3fe1be46a994272793');
+    });
+
+    test('It returns the value of the Root X-Ray segment ID properly formatted', () => {
+
+      // Prepare
+      delete process.env._X_AMZN_TRACE_ID;
+      const service = new EnvironmentVariablesService();
+
+      // Act
+      const value = service.getXrayTraceId();
+
+      // Assess
+      expect(value).toEqual(undefined);
+    });
+
+  });
+
+});

packages/logger/src/Logger.ts

@@ -117,7 +117,8 @@ class Logger extends Utility implements ClassThatLogs {
 
   private static readonly defaultServiceName: string = 'service_undefined';
 
-  private envVarsService?: EnvironmentVariablesService;
+  // envVarsService is always initialized in the constructor in setOptions()
+  private envVarsService!: EnvironmentVariablesService;
 
   private logEvent: boolean = false;
 
@@ -455,7 +456,7 @@ class Logger extends Utility implements ClassThatLogs {
       logLevel,
       timestamp: new Date(),
       message: typeof input === 'string' ? input : input.message,
-      xRayTraceId: this.getXrayTraceId(),
+      xRayTraceId: this.envVarsService.getXrayTraceId(),
     }, this.getPowertoolLogData());
 
     const logItem = new LogItem({
@@ -545,23 +546,6 @@ class Logger extends Utility implements ClassThatLogs {
     return <number> this.powertoolLogData.sampleRateValue;
   }
 
-  /**
-   * It returns the current X-Ray Trace ID parsing the content of the `_X_AMZN_TRACE_ID` env variable.
-   *
-   * The X-Ray Trace data available in the environment variable has this format:
-   * `Root=1-5759e988-bd862e3fe1be46a994272793;Parent=557abcec3ee5a047;Sampled=1`,
-   *
-   * The actual Trace ID is: `1-5759e988-bd862e3fe1be46a994272793`.
-   *
-   * @private
-   * @returns {string}
-   */
-  private getXrayTraceId(): string {
-    const xRayTraceId = this.getEnvVarsService().getXrayTraceId();
-
-    return xRayTraceId.length > 0 ? xRayTraceId.split(';')[0].replace('Root=', '') : xRayTraceId;
-  }
-
   /**
    * It returns true if the provided log level is valid.
    *